EFA Botswana Birds
Okavango River Basin Technical
Diagnostic Analysis:
Environmental Flow Module
Specialist Report
Country: Botswana
Discipline: Birds
Peter Hancock
June 2009
EFA Botswana Birds
Okavango River Basin Technical
Diagnostic Analysis:
Environmental Flow Module
Specialist Report
Country: Botswana
Discipline: Birds
Author: P Hancock
Date: June, 2009
2
EFA Botswana Birds
EXECUTIVE SUMMARY
Birds are generally regarded as good environmental indicators and several species found in
the Okavango Delta are sufficiently well-known to be useful for the purpose of predicting
ecological changes under varying water flow regimes. These are primarily waterbirds that
feed and/or breed in close association with water, or terrestrial birds that depend on riparian
or other water-related habitats.
This chapter lists the birds chosen as indicators for the three sites in the Okavango Delta in
Botswana, and describes their characteristics in terms of flow-related habitats occupied, and
their known water needs. This information is derived from a detailed literature review, and
knowledge gained during fieldwork in the Okavango prior to this study.
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EFA Botswana Birds
TABLE OF CONTENTS
EXECUTIVE SUMMARY ........................................................................................ 3
ACKNOWLEDGEMENTS ....................................................................................... 8
1.
INTRODUCTION ........................................................................................... 8
1.1 Background ................................................................................................... 8
1.2 Okavango River Basin EFA Objectives and Workplan .................................. 8
1.2.1
Project objectives ....................................................................................... 8
1.3 Layout of this report ....................................................................................... 9
2 STUDY AREA ................................................................................................. 10
2.1 Description of the Okavango Basin ............................................................. 10
2.2 Delineation of the Okavango Basin into Integrated Units of Analysis .......... 11
2.3 Overview of sites ......................................................................................... 12
2.4 Discipline-specific description of Botswana sites ......................................... 12
3.
IDENTIFICATION OF INDICATORS AND FLOW CATEGORIES ............... 14
3.1 Indicators ..................................................................................................... 14
3.1.1
Introduction .............................................................................................. 14
3.2 Indicator list for birds ................................................................................... 14
3.3 Description and location of indicators .......................................................... 15
3.4 Flow categories river sites ........................................................................ 18
3.5 Inundation categories delta sites .............................................................. 21
4 LITERATURE REVIEW .................................................................................. 22
Introduction ........................................................................................................... 22
Indicator 1 - Piscivores of open water ................................................................... 23
Main characteristics of Indicator 1 ......................................................................... 23
Life cycle attributes of Indicator1 ........................................................................... 24
Links to flow .......................................................................................................... 24
Indicator 2 Piscivores of shallow water and lagoons .......................................... 25
Main characteristics of indicator ............................................................................ 25
Life cycle attributes ............................................................................................... 25
Links to flow .......................................................................................................... 25
Indicator 3 Piscivores and invertebrate feeders in isolated pools ....................... 26
Main characteristics of indicator ............................................................................ 26
Life cycle attributes ............................................................................................... 26
Links to flow .......................................................................................................... 27
Indicator 4 Specialist feeders on floodplains, receding waters ........................... 28
Main characteristics of indicator ............................................................................ 28
Life cycle attributes ............................................................................................... 28
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EFA Botswana Birds
Links to flow .......................................................................................................... 29
Indicator 5 Specialist feeders in water lily-covered inlets ................................... 29
Main characteristics of indicator ............................................................................ 29
Life cycle attributes ............................................................................................... 29
Links to flow .......................................................................................................... 30
Indicator 6 Specialist feeders in riverine fruit trees ............................................. 30
Main characteristics of indicator ............................................................................ 30
Life cycle attributes ............................................................................................... 30
Links to flow .......................................................................................................... 30
Indicator 7 Breeders in reedbeds, floodplains .................................................... 31
Main characteristics of indicator ............................................................................ 31
Life cycle attributes ............................................................................................... 31
Links to flow .......................................................................................................... 32
Indicator 8 Breeders in riverine overhanging trees ............................................. 32
Main characteristics of indicator ............................................................................ 32
Life cycle attributes ............................................................................................... 32
Links to flow .......................................................................................................... 33
Indicator 9 Breeders on banks ........................................................................... 33
Main characteristics of indicator ............................................................................ 33
Life cycle attributes ............................................................................................... 33
Links to flow .......................................................................................................... 34
Indicator 10 Breeders on emergent rocks, sandbanks, islands .......................... 34
Main characteristics of indicator ............................................................................ 34
Life cycle attributes ............................................................................................... 34
Links to flow .......................................................................................................... 35
Summary ............................................................................................................... 35
5 DATA COLLECTION AND ANALYSIS ........................................................... 36
Methods for data collection and analysis .............................................................. 36
A summary of present understanding of the predicted responses of all bird
indicators to potential changes in the flow regime ................................................. 36
Indicator 1 (Piscivores of open water) ............................................................... 37
Indicator 2 (Piscivores of shallow water and lagoons) ....................................... 38
Indicator 3 (Piscivores and invertebrate feeders in isolated pools) .................... 39
Indicator 4 (Specialist feeders on floodplains) ................................................... 40
Indicator 5 (Specialist feeders In waterlily covered inlets) ................................. 41
Indicator 6 (Specialist feeders in riverine fruit trees) .......................................... 42
Indicator 7 (Breeders in reedbeds and floodplains) ........................................... 43
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EFA Botswana Birds
Indicator 8 (Breeders in riverine overhanging trees) .......................................... 44
Indicator 9 (Breeders on banks) ........................................................................ 45
Indicator 10 (Breeders on emergent rocks, sandbanks and islands) ................. 46
7.
CONCLUSION ............................................................................................ 47
8.
REFERENCES ............................................................................................ 48
APPENDIX A: FULL DESCRIPTIONS OF INDICATORS ..................................... 50
1.1 Transboundary Diagnostic Analysis of the Botswana Portion of the
Okavango River Basin: Land Use Planning ............. Error! Bookmark not defined.
LIST OF FIGURES
Figure 1: Upper Okavango River Basin from sources to the northern end of the Delta 10
Figure 2: The Okavango River Basin, showing drainage into the Okavango Delta and the
Makgadikgadi Pans .................................................................. 11
Figure 3: Three representative years for Site 1: Cuebe River @ Capico, illustrating the
approximate division of the flow regime into four flow seasons 19
Figure 4: Three representative years for Site 2: Cubango River @ Mucindi, illustrating the
approximate division of the flow regime into four flow seasons 19
Figure 5: Three representative years for Site 3 Cuito River @ Cuito Cuanavale,
illustrating the approximate division of the flow regime into four
flow seasons ............................................................................ 20
Figure 6: Three representative years for Site 4: Okavango River @ Kapoka (hydrological
data from Rundu), illustrating the approximate division of the flow
regime into four flow seasons ................................................... 20
Figure 7: Three representative years for Site 5: Okavango River @ Popa (hydrological
data from Mukwe), illustrating the approximate division of the flow
regime into four flow seasons ................................................... 21
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EFA Botswana Birds
LIST OF TABLES
Table 1: Location of the eight EFA sites ........................................................................ 12
Table 2: List of indicators for birds and those chosen to represent each site ............... 15
Table 3: Questions to be addressed at the Knowledge Capture Workshop, per indicator
per site. In all cases, `natural' embraces the full range of natural
variability .................................................................................. 21
Table 4: Inundation categories for the Okavango Delta as recognised by the HOORC
inundation model ...................................................................... 22
Table 5: Predicted response to possible changes in the flow regime of Piscivores of open
water as an indicator in the Okavango River ecosystem ......... 37
Table 6: Predicted response to possible changes in the flow regime of Piscivores of
shallow water and lagoons as an indicator in the Okavango River
ecosystem ................................................................................ 38
Table 7: Predicted response to possible changes in the flow regime of Piscivores and
invertebrate feeders in isolated pools as an indicator in the
Okavango River ecosystem ..................................................... 39
Table 8: Predicted response to possible changes in the flow regime of Piscivores and
invertebrate feeders on floodplains as an indicator in the
Okavango River ecosystem ..................................................... 40
Table 9: Predicted response to possible changes in the flow regime of Specialist feeders
in waterlily covered inlets as an indicator in the Okavango River
ecosystem ................................................................................ 41
Table 10: Predicted response to possible changes in the flow regime of Specialist feeders
in riverine fruit trees as an indicator in the Okavango River
ecosystem ................................................................................ 42
Table 11: Predicted response to possible changes in the flow regime of Breeders in
reedbeds and floodplains as an indicator in the Okavango River
ecosystem ................................................................................ 43
Table 12: Predicted response to possible changes in the flow regime of Breeders in
riverine overhanging trees as an indicator in the Okavango River
ecosystem ................................................................................ 44
Table 13: Predicted response to possible changes in the flow regime of Breeders on
banks as an indicator in the Okavango River ecosystem ......... 45
Table 14: Predicted response to possible changes in the flow regime of Breeders on
emergent rocks, sandbanks and islands as an indicator in the
Okavango River ecosystem ..................................................... 46
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EFA Botswana Birds
ABBREVIATIONS
ABBREVIATION
MEANING
DTM
Digital Terrain Model
BLB BirdLife
Botswana
ACKNOWLEDGEMENTS
Special thanks are due to Dr SJ Tyler for reviewing and commenting on the draft of this
report.
1. INTRODUCTION
1.1 Background
An Environmental Protection and Sustainable Management of the Okavango River Basin
(EPSMO) Project is being implemented under the auspices of the Food and Agriculture
Organization of the United Nations (UN-FAO). One of the activities is to complete a
transboundary diagnostic assessment (TDA) for the purpose of developing a Strategic Action
Plan for the basin. The TDA is an analysis of current and future possible causes of
transboundary issues between the three countries of the basin: Angola, Namibia and
Botswana. The Okavango Basin Steering Committee (OBSC) of the Okavango River Basin
Water Commission (OKACOM) noted during a March 2008 meeting in Windhoek, Namibia,
that future transboundary issues within the Okavango River basin are likely to occur due to
developments that would modify flow regimes. The OBSC also noted that there was
inadequate information about the physico-chemical, ecological and socioeconomic effects of
such possible developments. OBSC recommended at this meeting that an Environmental
Flow Assessment (EFA) be carried out to predict possible development-driven changes in
the flow regime of the Okavango River system, the related ecosystem changes, and the
consequent impacts on people using the river's resources.
The EFA is a joint project of EPSMO and the Biokavango Project. One part of the EFA is a
series of country-specific specialist studies, of which this is the bird report for Botswana.
1.2
Okavango River Basin EFA Objectives and Workplan
1.2.1 Project
objectives
The goals of the EFA are:
·
to summarise all relevant information on the Okavango River system and its
users, and collect new data as appropriate within the constraints of the EFA
·
to use these to provide scenarios of possible development pathways into the
future for consideration by decision makers, enabling them to discuss and
negotiate on sustainable development of the Okavango River Basin;
·
to include in each scenario the major positive and negative ecological, resource-
economic and social impacts of the relevant developments;
8
EFA Botswana Birds
·
to complete this suite of activities as a pilot EFA, due to time constraints, as input
to the TDA and to a future comprehensive EFA.
The specific objectives are:
·
to ascertain at different points along the Okavango River system, including the
Delta, the existing relationships between the flow regime and the ecological
nature and functioning of the river ecosystem;
·
to ascertain the existing relationships between the river ecosystem and peoples'
livelihoods;
·
to predict possible development-driven changes to the flow regime and thus to
the river ecosystem;
·
to predict the impacts of such river ecosystem changes on people's livelihoods.
·
to use the EFA outputs to enhance biodiversity management of the Delta.
·
to develop skills for conducting EFAs in Angola, Botswana, and Namibia.
1.3
Layout of this report
This report starts with a description of the study area, the Okavango River basin, with
particular emphasis on the Botswana component viz. the Panhandle, Okavango Delta and
distal distributaries such as the Boteti River. An overview is given of each of the three
representative sites in the country, as follows:
1. Okavango Panhandle at Shakawe
2. Okavango Delta at Xakanaxa
3. Boteti River at Chanoga
The characteristics of each of these sites that are relevant for birds are described in terms of
available habitat and species assemblages.
This is followed by a section containing a list of suitable bird indicators that can be used to
show changes in the environment under a variety of flow regimes. These bird indicators are
primarily, but not exclusively waterbirds. Each indicator is described in terms of
representative species, their flow-related location in the ecosystem, and their known water
needs. The water flows for each site are also described in this section, based on information
provided by the hydrological team.
After the identification of the bird indicators, there is a detailed literature review focusing on
what is known about these indicators (relative to water flows) in the Okavango system, and
where this information is scant, it is supplemented by reviewing available literature for these
species from the Southern African region. The references consulted are detailed in a later
section at the end of this report.
Limited fieldwork was undertaken specifically for this project, but prior ornithological research
that was conducted by the author at the three Botswana sites is summarised next, and the
details relative to each indicator are provided in a series of tables, forming the last part of the
body of the report. A short appendix summarises the particulars of the ten bird indicators.
The responses of each indicator to varied water flows, in the form of Response Curves for
each, appears elsewhere.
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EFA Botswana Birds
2 STUDY
AREA
2.1
Description of the Okavango Basin
The Okavango River Basin consists of the areas drained by the Cubango, Cutato, Cuchi,
Cuelei, Cuebe, and Cuito rivers in Angola, the Okavango River in Namibia and Botswana,
and the Okavango Delta (Figure 2.1). This basin topographically includes the area that was
drained by the now fossil Omatako River in Namibia. Outflows from the Okavango Delta are
drained through the Thamalakane and then Boteti Rivers, the latter eventually joining the
Makgadikgadi Pans. The Nata River, which drains the western part of Zimbabwe, also joins
the Makgadikgadi Pans. On the basis of topography, the Okavango River Basin thus
includes the Makgadikgadi Pans and Nata River Basin (Figure 2.2). This study, however,
focuses on the parts of the basin in Angola and Namibia, and the Panhandle/Delta/Boteti
River complex in Botswana. The Makgadikgadi Pans and Nata River are not included.
Upper Okavango River Basin
N
W
E
S
Cu
t
Cu
a
#
t
o
c
h
i
#
C
C
u
u
#
it
a
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le
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#
C
e
M nongue
ba
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#
Major settlement
g
h
o
i
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u
C ito Cuanavale
River
C
#
ue
Fossil river
be
C
Panhandle
ANGOLA
uiri
Permanent swamps
ri
#
Seasonal swamps
Cubango
Cuito
NAMIBIA
Okavango
#
Rundu
#
#
#
0
300 Kilometers
#
Figure 1: Upper Okavango River Basin from sources to the northern end of the Delta
10
EFA Botswana Birds
Okavango River Basin
N
W
E
S
C
u
ta
Cu
#
to
c
hi
#
C
C
ui
ua
#
t
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M nongue
ub
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ANGOLA
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#
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Cubango
Cuito
NAMIBIA
Okavango
#
Rundu
#
# #
#
##
#
#
#
Maun
#
Makgadikgadi Pans
# Ghanzi
#
Major settlement
River
Fossil river
Panhandle
0
600 Kilometers
Permanent swamps
Seasonal swamps
Figure 2: The Okavango River Basin, showing drainage into the Okavango Delta and the
Makgadikgadi Pans
2.2
Delineation of the Okavango Basin into Integrated Units of Analysis
Within the Okavango River Basin, no study could address every kilometre stretch of the river,
or every person living within the area, particularly a pilot study such as this one. Instead,
representative areas that are reasonably homogeneous in character may be delineated and
used to represent much wider areas, and then one or more representative sites chosen in
each as the focus for data-collection activities. The results from each representative site can
then be extrapolated over the respective wider areas.
Using this approach, the Basin was delineated into Integrated Units of Analysis
(EPSMO/Biokavango Report Number 2; Delineation Report) by:
dividing the river into relatively homogeneous longitudinal zones in terms of:
hydrology;
geomorphology;
water chemistry;
fish;
aquatic invertebrates;
vegetation;
harmonising the results from each discipline into one set of biophysical river zones;
11
EFA Botswana Birds
dividing the basin into relatively homogeneous areas in terms of social systems;
harmonising the biophysical river zones and the social areas into one set of Integrated Units
of Analysis (IUAs).
The 19 recognised IUAs were then considered by each national team as candidates for the
location of the allocated number of study sites:
Angola: three
sites
Namibia: two
sites
Botswana: three sites.
The sites chosen by the national teams are given in Table 2.1.
Table 1: Location of the eight EFA sites
EFA Site No
Country
River
Location
1 Angola
Cuebe
Capico
2 Angola
Cubango
Mucundi
3 Angola
Cutio Cuito
Cuanavale
4 Namibia
Okavango
Kapako
5 Namibia
Okavango
Popa
Falls
Panhandle at
6 Botswana
Okavango
Shakawe
7
Botswana
Khwai
Xakanaka in Delta
8 Botswana
Boteti Chanoga
2.3 Overview
of
sites
Site 6: Okavango River in the Panhandle at Shakawe
Site 7: Eastern Okavango Delta around Xakanaxa
Site 8: Boteti River at Chanoga
2.4 Discipline-specific
description of Botswana sites
Site 6: Panhandle at Shakawe
The Okavango Panhandle, where the river meanders between two faultlines, is a unique
area for birds. The open waters of the river itself are utilised by a few fish-eating species that
can capture their prey in this habitat viz. African Fish-Eagles, Pied Kingfishers, African
Darters and Reed Cormorants. The first two hunt from perches in the riverine trees aligning
the river, while the others pursue fish underwater, taking advantage of its clarity. Pel's
Fishing-Owl is relatively common in the panhandle, and is the nocturnal equivalent of the
Fish-Eagle. At this site, the outer curves of the river cut steep banks that are used as nesting
sites by Giant, Pied and Malachite kingfishers and Southern Carmine and White-fronted bee-
eaters. The bee-eaters in particular breed in large colonies and are an important tourist
attraction the colonies near the Brigades in Shakawe and at Drotsky's Cabins are
particularly important. Sand eroded from the outer curves is thrown up on the inner curves in
12
EFA Botswana Birds
the form of low-lying sandbanks which are exposed during periods of low flow during
September to December every year, and these are used by globally threatened African
Skimmers, as well as Water Thick-knees, for breeding sites. The Panhandle is the most
important breeding area for African Skimmers in Botswana.
The river fringes are lined with Papyrus and `Hippo grass' (Vossia cuspidate) which are key
components of the habitat of the Greater Swamp Warbler, a species which, in Botswana, is
virtually confined to the Panhandle and permanent swamp. This vegetation is also used by
Squacco and Green-backed Herons as perches from which to catch fish; during the annual
`barbel runs', which occur in the Panhandle primarily during the low flows of September, they
are joined by large numbers of other egrets and herons.
The area between the faultlines, away from the river is a mixture of floodplain and
`backswamp' utilised by egrets, herons, jacanas, ducks and geese, and African Openbills,
among other species. This area floods seasonally and as the water flows onto the
floodplains, many fish eating birds are attracted here. Similarly when the waters recede and
fish are trapped in drying pools, this area is important for many piscivorous birds, including
the globally threatened Slaty Egret.
Site 7: Eastern Delta around Xakanaxa
At Xakanaxa, the key habitats for birds are the open waters of the lagoons and the
Maunachira/Khwai River, and the permanently wet areas characterised by stands of
Papyrus. In general, this site is not good for birds, as shown by the low species diversity and
numbers. There are only a few piscivorous species that can hunt successfully in the open
waters of Xakanaxa Lediba, and these include those (like the African Fish-Eagle, Pel's
Fishing-Owl and kingfishers) that hunt from perches in the riparian trees adjacent to the
water, and the diving birds (such as African Darters and Reed Cormorants) that pursue fish
underwater. The Maunachira/Khwai River is very poor in nutrients and does not support
many bird species Reed Cormorants and African Darters are the most important species,
(although not numerous) with low numbers of African Pygmy-Goose and African Jacana
where water lilies are found in quiet backwaters. Papyrus and Water Figs lining the river are
used as hunting perches by the occasional Squacco Heron.
An important feature of Xakanaxa Lediba is its islands of Water Figs used as breeding sites
for African Darters, Reed Cormorants and other birds such as Marabou and Yellow-billed
storks. African Spoonbills and a variety of herons and egrets breed here too, and the globally
threatened Slaty Egret has also been recorded breeding here. These birds choose the
security of the islands for breeding, but fly to feed elsewhere in the Delta due to the low
productivity of this area in terms of fish and aquatic macro-invertebrates.
The wetland habitat at this site is currently permanent, and is juxtaposed against dry land
consequently there are no significant floodplains, and water levels do not fluctuate much
seasonally or between years. This may account for its low attractiveness for waterbirds.
Site 8: Chanoga
Perhaps surprisingly, this site is one of the most important areas for waterbirds in the
Okavango Delta. Although it is unprotected, large numbers of ducks, geese and other
waterbirds utilise this site when it has water, since the waters are rich in nutrients that have
been leached out of the upstream areas, or accumulated from grazers that are present when
the area is dry. White-faced and White-backed duck, Red-billed Teal and Comb Duck are the
most numerous species, but the water lily-covered areas attract significant numbers of
13
EFA Botswana Birds
African Pygmy-Goose, and African and Lesser jacana. The muddy margins are utilised by
African Sacred and Glossy ibis, and Blacksmith Lapwings nest along the short-grass verges.
Although this site does not support any waterbirds when it is dry, the drying-flooding-drying
cycle is vitally important from a bird perspective; when Chanoga Lediba dries, large numbers
of large fish (that have thrived in the nutrient-rich conditions) are trapped and attract
hundreds of Great White Pelicans, Marabou Storks, African Fish-Eagles and other large
piscivorous birds. This is particularly important for the pelicans which feed here and commute
to the Nata River Delta to feed their flightless chicks; their breeding appears to be
synchronised with the drying of the distal reaches of the Okavango system when such `fish-
traps' occur. Also found at Chanoga in large numbers when the waters recede are African
Openbills, normally regarded as floodplain specialists, which here exploits the shallow water
margins where Pina occidentais, and Lanistes snails are exposed as waters recede (these
molluscs form its main diet). Globally threatened Wattled Cranes also feed along the margins
of Chanoga Lediba; as the lagoon dries and the sedges transfer their nutrients into
underground corms and bulbs, these are excavated and eaten by the cranes.
In summary, this site, although not varied in terms of habitats, is very important for waterbirds
due to the large numbers that congregate here when conditions are favourable.
3. IDENTIFICATION
OF
INDICATORS AND FLOW CATEGORIES
3.1 Indicators
3.1.1 Introduction
Biophysical indicators are discipline-specific attributes of the river system that respond to a
change in river flow by changing in their:
abundance;
concentration; or
extent (area).
Social indicators are attributes of the social structures linked to the river that respond to
changes in the availability of riverine resources (as described by the biophysical indicators).
The indicators are used to characterise the current situation and changes that could occur
with development-driven flow changes.
Within any one biophysical discipline, key attributes can be grouped if they are expected to
respond in the same way to the flow regime of the river. By example, fish species that all
move on to floodplains at about the same time and for the same kinds of breeding or feeding
reasons could be grouped as Fish Guild X.
3.2
Indicator list for birds
In order to cover the major characteristics of the river system and its users many indicators
may be deemed necessary. For any one EF site, however, the number of indicators is
limited to ten (or fewer) in order to make the process manageable. The full list of indicators
was developed collaboratively by the country representatives for the discipline C Santos, M
Paxton and P Hancock - and is provided in Table 3.1. Further details of each indicator,
14
EFA Botswana Birds
including the representative species of each biological one, are given in Appendix A, and
discussed fully below.
Table 2: List of indicators for birds and those chosen to represent each site
Indicato
Sites represented no more than ten
r
Indicator name
indicators per site
Number
1 2 3 4 5 6 7 8
1
Piscivores of open water
X
X
X
2
Piscivores of shallow water and lagoons
X
X
X
3
Piscivores and invertebrate feeders,
X X X
isolated pools
Specialist feeders on floodplains,
4
receding waters
X X X
Specialist feeders in waterlily-covered
5
X X X
inlets
6
Specialist feeders in riverine fruit trees
X
X
X
Breeders in reedbeds, and on
7
X X
floodplains
8
Breeders in riverine overhanging trees
X
X
9
Breeders on banks
X
X
Breeders on emergent rocks, sandbanks
10
X X
and islands
3.3
Description and location of indicators
Birds Indicator 1
Name: Piscivores of open water
Description: These are fish-eating birds that are able to catch fish in open, deep waters by
diving or swimming after them.
Representative species:
African Fish-Eagle, Reed Cormorant, Pied Kingfisher.
Other characteristic species: African Darter, Giant Kingfisher
Flow-related location: Channels in permanent swamp
Lagoons
in
permanent
swamp
Seasonal pools in seasonally flooded zone
Known water needs: Open water surface i.e. devoid of floating vegetation such as
waterlilies and Salvinia. Clarity of water may be a factor.
Birds Indicator 2
Name: Piscivores of shallow water and lagoons
15
EFA Botswana Birds
Description: These are fish-eating birds that are able to catch fish near the edge, from a
perch, or by static hunting in water shallower than their leg length.
Representative species:
Pel's Fishing-Owl, larger herons and egrets (Great Egret,
Yellow-billed Egret, Grey Heron)
Other characteristic species: Black-crowned Night-Heron
Flow-related location: Channels in permanent swamp
Lagoons
in
permanent
swamp
Seasonal pools in seasonally flooded zone
Seasonal sedgeland in seasonally flooded zone
Seasonal grassland in seasonally flooded zone
Known water needs: Shallow water, preferably not flowing
Birds Indicator 3
Name: Piscivores and invertebrate feeders, isolated pools
Description: These are birds that capitalise on isolated pools on floodplains or in river
channels to catch fish and invertebrates
Representative species:
Great White Pelican, Squacco Heron, Little Egret, Red-billed
Teal, Hottentot Teal
Other characteristic species: Black Heron, Hamerkop, Marabou Stork, Glossy Ibis
Flow-related location: Seasonal pools in seasonally flooded zone
Seasonal sedgeland in seasonally flooded zone
Seasonal grassland in seasonally flooded zone
Known water needs: Fluctuating amounts of water e.g. a pulse of water that would inundate
a floodplain or channel, and then contract, concentrating fish and invertebrates
Birds Indicator 4
Name: Specialist feeders on floodplains
Description: These birds feed on molluscs, frogs, fish or selective vegetation occurring in
floodplain situations often along the water's edge
Representative species:
African Openbill, Slaty Egret, Wattled Crane
Other characteristic species:
Flow-related location: Seasonal sedgeland in seasonally flooded zone
Seasonal grassland in seasonally flooded zone
Known water needs: Sufficient water to inundate floodplains and result in shallow areas for
feeding
Birds Indicator 5
Name: Specialist feeders in water-lily covered inlets
16
EFA Botswana Birds
Description: These are birds that need lily-covered inlets or floodplain pools or lagoons for
feeding
Representative species:
African Jacana, Lesser Jacana
Other characteristic species: African Pygmy-Goose, Allen's Gallinule
Flow-related location: Inlets off channels in permanent swamp
Lagoons
in
permanent
swamp
Seasonal pools in seasonally flooded zone
Known water needs: Permanent water with little or no fluctuation
Birds Indicator 6
Name: Specialist feeders in riverine fruit trees
Description: These are frugivorous birds that occupy the riparian vegetation for the
purpose of feeding on fruit
Representative
species:
African Green-Pigeon, Black-collared Barber, Burchell's
Starling
Other characteristic species: Meyer's Parrot, Dark-capped Bulbul
Flow-related location: On alluvial levees of channels in permanent swamp, or at water's edge
of islands/mainland in seasonal sedgeland and grassland in seasonally flooded zone
Known water needs: Surface water or high water table to ensure well-being of the fruit-
bearing trees
Birds Indicator 7
Name: Breeders in reedbeds, and on floodplains
Description: These are birds from a variety of families that nest in Phragmites reeds along
channels or in Cyperus beds on floodplains
Representative species:
Slaty Egret, Rufous-bellied Heron, Wattled Crane, weaver spp.
Other characteristic species: Greater Swamp-Warbler, Great Egret
Flow-related location: Channels in permanent swamp, seasonal sedgeland and grassland in
seasonally flooded zone
Known water needs: Permanently or seasonally flooded; if areas dry out for more than one
year, they become unsuitable. Unseasonal high flood levels may inundate nests
Birds Indicator 8
Name: Breeders in riverine overhanging trees
Description: Colonial breeders or solitary nesters requiring over-hanging vegetation for
nest safety or fledglings vacating the nest
17
EFA Botswana Birds
Representative species:
African Darter, Reed Cormorant
Other characteristic species: Green-backed Heron, White-backed Night-Heron
Flow-related location: Trees along margins of channels in permanent swamp, or along edge
of small islands or mainland in seasonal sedgeland and grassland in seasonally flooded zone
Known water needs: Nesting trees must stand in water for the duration of the breeding
season
Birds Indicator 9
Name: Breeders on banks
Description: Birds that require vertical banks for nest holes, or the grassy tops of banks for
nest sites and fledgling development.
Representative species:
Southern Carmine Bee-eater, White-fronted Bee-eater, Pied
Kingfisher.
Other characteristic species: Malachite Kingfisher, Giant Kingfisher
Flow-related location: Channels in permanent swamp where the river is incised to form
vertical banks, or at the edge of seasonal sedgeland and grassland in seasonally flooded
zone.
Known water needs: Sufficient water to erode the bank and keep the face vertical and clear
of vegetation.
Birds Indicator 10
Name: Breeders on emergent rocks, sandbanks and islands
Description: Birds which are totally dependent on emerged rocks, sandbanks and sandy
islands for nesting purposes
Representative species:
Rock Pratincole, African Skimmer, Water Thick-knee
Other characteristic species: None
Flow-related location: On the inside of meanders in the Okavango River and other fast-
flowing channels
Known water needs: Fluctuating water levels, with low level during the period September to
November. Sediment load.
3.4
Flow categories river sites
One of the main assumptions underlying the EF process to be used in the TDA is that it is
possible to identify parts of the flow regime that are ecologically relevant in different ways
and to describe their nature using the historical hydrological record. Thus, one of the first
steps in the EFA process, for any river, is to consult with local river ecologists to identify
18
EFA Botswana Birds
these ecologically most important flow categories. This process was followed at the
Preparation Workshop in September 2008 and four flow categories were agreed on for the
Okavango Basin river sites:
Dry season
Transitional Season 1
Flood Season
Transitional Season 2.
Tentative seasonal divisions for river Sites 1-5 are shown in Figures 3.1 to 3.5. These
seasonal divisions will be formalised by the project hydrological team in the form of
hydrological rules in the hydrological model. In the interim they provide useful insights into
the flow regime of the river system suggesting, along with the hydrographs, a higher within-
year flow variability of the Cuebe River and a higher year-on-year variability of the Cubango
River.
It is planned to use similar flow seasons for the remaining river sites: 6 and 8.
120
Wet
100
Trans 1
Trans
n 2
Dry
80
Year
Y
2
ear
60
Year
Y
1
ear
Year
Y
3
ear
40
20
0
O
N
D
J
D
F
M
A
M
J
J
M
J
A
S
Figure 3: Three representative years for Site 1: Cuebe River @ Capico, illustrating the
approximate division of the flow regime into four flow seasons
1200
Wet
1000
Trans 1
Trans 2
Dry
800
Year 1
600
Year 2
Year 3
400
200
0
O
N
D
J
D
F
M
A
M
J
J
M
J
A
S
Figure 4: Three representative years for Site 2: Cubango River @ Mucindi, illustrating the
approximate division of the flow regime into four flow seasons
19
EFA Botswana Birds
250
Wet
Dry
200
Trans 1
Trans 2
150
Year 1
ear
Year 2
ear
100
Year 3
ear
50
0
O
N
D
J
F
M
A
M
J
J
M
J
A
S
Figure 5: Three representative years for Site 3 Cuito River @ Cuito Cuanavale, illustrating the
approximate division of the flow regime into four flow seasons
1000
900
Wet
We
800
Dry
Dr
Tra
Tr n
a s
n 1
s
Tra
Tr n
a s
n 2
s
Dry
Dr
700
600
Year 1
500
Year 2
400
Year 3
300
200
100
0
O
N
D
J
F
M
A
M
J
J
M
J
A
S
Figure 6: Three representative years for Site 4: Okavango River @ Kapoka (hydrological data
from Rundu), illustrating the approximate division of the flow regime into four flow
seasons
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EFA Botswana Birds
1800
1600
Wet
1400
Dry
Trans 1
n
Trans
n 2
Dry
1200
1000
Year 3
00
Year 2
800
Year 1
600
400
200
0
O
N
D
J
F
M
A
M
J
J
M
J
A
S
Figure 7: Three representative years for Site 5: Okavango River @ Popa (hydrological data
from Mukwe), illustrating the approximate division of the flow regime into four flow
seasons
The literature review (Chapter 4) and data collection and analysis exercises (Chapter 5) are
focused on addressing what is initially expected to be nine main questions related to these
flow seasons (Table 3.2).
Table 3: Questions to be addressed at the Knowledge Capture Workshop, per indicator per
site. In all cases, `natural' embraces the full range of natural variability
Question
number
Season
Response of indicator if:
1
Onset is earlier or later than natural median/average
2
Dry Season
Water levels are higher or lower than natural median/average
3
Extends longer than natural median/average
4
Duration is longer or shorter than natural median/average - i.e. hydrograph
Transition 1
is steeper or shallower
5
Flows are more or less variable than natural median/average l
6
Onset is earlier or later than natural median/average synchronisation with
Flood season
rain may be changed
7
Natural median/average proportion of different types of flood year changed
8
Onset is earlier or later than natural median/average
Transition 2
9
Duration is longer or shorter than natural median/average i.e. hydrograph
is steeper or shallower
3.5
Inundation categories delta sites
The recognised river flow categories are not relevant in the Delta, where inundation is the
major driver of ecosystem form and functioning. The main inundation categories recognised
by the inundation model developed by the Harry Oppenheimer Okavango Research Centre
(HOORC) are used here (Table 3.3).
21
EFA Botswana Birds
Table 4: Inundation categories for the Okavango Delta as recognised by the HOORC inundation
model
Inundation Inundation category
Description
category
name
number
1 CH-ps
Channels in permanent
Main channels that never dry up
swamp
2 L-ps
Lagoons in permanent
Areas of open water away from the main
swamp
channels
3 B-ps
Backswamp in
Extensive stands of Papyrus and sparse
permanent swamp
Phragmites standing in water
4 SP-sf
Seasonal pools in
Pools on floodplains that dry seasonally
seasonally flooded zone
5 SED-sf
Seasonal sedgeland in
Floodplains that flood regularly and are
seasonally flooded zone dominated by sedges such as Cyperus
6 GR-sf
Seasonal grassland in
Grassland that is infrequently inundated
seasonally flooded zone
7 S-sf
Savanna-dried
Dryland areas that are only occasionally
floodplain in seasonally
flooded
flooded zone
4 LITERATURE
REVIEW
Introduction
A literature review was undertaken, focusing mainly on work done on the bird indicator
species in the Okavango Delta most of the studies on birds in the Okavango Delta have
been published in the biannual BirdLife Botswana scientific journal Babbler. Many bird
species in Botswana are `data deficient', and in these instances, regional works on their
behaviour and ecology were consulted in this regard, the Southern African Ornithological
journal Ostrich proved invaluable. Some of the indicator species have been the subject of
detailed studies in other parts of their range e.g. Bento's thesis on the Status and Prospects
of Wattled Cranes Grus carunculatus in the Zambezi Delta, and these provided
supplementary information. The literature consulted is detailed in SECTION 6 - References
Birds are an important part of the Okavango Delta ecosystem, both for their varied ecological
roles and their value as a component of Botswana's growing tourism industry. Generally, the
status and distribution of birds of the Okavango Delta are quite well-documented e.g. Bird
Atlas of Botswana (Penry, 1994); Inventory of Birds of the Okavango Delta Ramsar site
(Hancock et al., 2007). Birds are also good environmental indicators as they are highly
mobile and can move when local conditions change e.g. the Wattled Crane is "an important
indicator species for assessing deleterious changes in wetland hydrological conditions, and
evaluating the impact of such changes on wetland biodiversity and subsistence production
systems" (Beilfuss et al., 2003). This makes the inclusion of birds in the environmental flow
assessment study essential.
A review of the literature also provided another perspective on the birds of the Okavango
Delta: according to Tyler and Bishop (1998), the Okavango Delta is recognised as an
22
EFA Botswana Birds
Important Bird Area (IBA) a site that meets international criteria set by the BirdLife
International Partnership. These criteria are listed below.
An Important Bird Area:
regularly holds significant numbers of a globally threatened species (or more than one
globally threatened species in the case of the Okavango)
holds a significant component of a group of species whose distributions are largely or wholly
confined to one biome
holds on a regular basis, >1% of a biogeographic population of a congregatory waterbird
species.
These criteria help focus attention on key bird species that could be adversely affected by
changes in the flow regime of the Okavango River viz. globally threatened birds and those
species which are largely restricted to the Okavango River Basin. The Wattled Crane is one
such species it is globally threatened, and according to Gibson et al. (2002), the Okavango
Delta holds the largest single population remaining of this species. It feeds and breeds on
seasonally inundated floodplains (Motsumi et al., 2003) areas likely to be most affected by
changes in water flows. Due to these factors, changes in environmental flows are more likely
to have significant consequences for Wattled Cranes than for other common and widespread
species, and it therefore makes sense to include the Wattled Crane among those species
chosen for modelling. Similarly with the Slaty Egret; it is globally threatened and nearly
endemic to the Okavango River Basin (with an estimated 85% of the global population found
here) and is a floodplain specialist (Hancock et al., 2005).
Other important bird species in the Okavango are those congregatory waterbirds that occur
in large numbers such that >1% of the population is found regularly in the Okavango Delta. A
decade of waterbird counts in the Okavango are documented in Tyler (2001) this review
also shows clearly the importance of the nutrient-rich distal reaches of the Okavango's
distributaries, namely the Thamalakane and Boteti Rivers. It is essential to include a site on
the Boteti in the predictive model since reduced flows will dramatically reduce water levels
here and impact large numbers of birds.
Indicator 1 - Piscivores of open water
Main characteristics of Indicator 1
These are the only birds that can access fish in deep, open water, whether it be the main
Okavango River, a major channel, or deep lagoons. Representative species are listed in the
table below:
Indicator 1 Piscivores of open water
General species
African Fish-Eagle, cormorants and darter, `fish-
eating' kingfishers
Representative species
African Fish-Eagle Haliaeetus vocifer
Reed Cormorant Phalacrocorax africanus
Pied Kingfisher Ceryle rudis
Some indicator species like the African Fish-Eagle hunt from a perch at the water's edge,
using sight to locate a fish near the surface, and then dive down and catch it in their talons.
Others, as exemplified by the Reed Cormorant, swim in the water and actively pursue and
catch fish underwater, in their bills, presumably by sight. The Pied Kingfisher can also access
fish in open water as it can hover above the water surface and then dive in, catching in its bill
23
EFA Botswana Birds
any fish seen. These three indicator species use different strategies to access fish in the
open waters; they are among the most common `waterbirds' at site 6 and have been quite
well studied e.g. the Pied Kingfisher (Douthwaite, 1982).
These birds are important in the system because they are the only ones that can exploit this
particular niche where the oligotrophic waters are clear and fish densities are low. The
African Fish-Eagle is one of the icons of the Okavango, and is an important part of the
tourism product. The larger species congregate at `barbel runs' which usually take place
during July/August/September.
Life cycle attributes of Indicator1
The African Fish-Eagle is territorial and adults are resident on their breeding territories
throughout the year these territories need to meet their year-round requirements in terms of
feeding and breeding. They eat exclusively fish, and their need for fish increases during the
winter months, from April to September, when they are breeding fish availability during the
latter part of this period when the chicks are large is critical. Nests are constructed in riparian
trees and are re-used in successive years. The fledged young scavenge a lot and are seen
at Barbel runs and fish die-offs e.g. at Guma Lagoon.
The Reed Cormorant spends most of its day in water pursuing fish that it has spotted, and
catching them underwater in its bill. It roosts communally at night on trees standing in water.
It also nests colonially on trees or reeds standing in water (see 3.9.2).
The Pied Kingfisher eats mostly small Cichlid fish (30 to 110mm in length) of the genera
Tilapia and Haplochromis these are located by sight from a perch or by hovering, and
caught with the bill by diving into the water. Their breeding is described in section 3.10.2.
Links to flow
The African Fish-Eagle must have open water in which to catch fish Salvinia and lily-
covered water surfaces are a disadvantage for this species. Drying lagoons or floodplain
pools with trapped fish are sought after especially by younger, non-territorial individuals.
Acacia nigrescens is the main nesting tree in the Okavango, followed by Diospyros
mespiliformis. They do not nest at the distal ends of the Delta's distributaries when the
channels are dry e.g. during low flow cycles, but soon recolonise these areas when flooded.
The Reed Cormorant prefers clear water without aquatic vegetation (submerged or floating
or emergent) for optimal fishing. The breeding of this species is also linked to water flows
(see below).
Since the Pied Kingfisher can hover, it is able to fish in deeper water, as long as it is clear it
also hunts in the shallows where fish are visible e.g. on floodplains. It feeds on small fish and
the fry of larger fish, which is why it frequents floodplains.
24
EFA Botswana Birds
Indicator 2 Piscivores of shallow water and lagoons
Main characteristics of indicator
This indicator is typified by Pel's Fishing-Owl, a nocturnal owl which specializes in catching
surface swimming fish (in its talons) in quiet backwaters overhung with large trees which are
used as fishing perches. Because the species occupies a narrow niche, any changes in the
system are likely to affect it. For example, when flood levels are high and water pushes into
hitherto dry areas, the Pel's Fishing-Owl is brought into contact with Verreaux's Eagle-Owl,
often to the detriment of the former (see Wright and Hancock, 2008).
The characteristic and representative species of this indicator are listed in the table below.
Indicator 2 Piscivores of shallow water and lagoons
General species
Pel's Fishing-Owl, large herons and egrets
Representative species
Pel's Fishing-Owl Scotopelia peli
Great Egret Egretta alba
Yellow-billed Egret Egretta intermedia
Life cycle attributes
Pel's Fishing-Owl is a specialist fish-eating nocturnal owl which catches surface swimming
fish from low perches over water or from sand banks. The following prey species have been
recorded: Clarias spp., Synodontus sp., Hepsetus odoe (in order of frequency in diet), and
also Seranochromis sp., Tilapia sp., Schilbe mystus and Petrocephalus catostoma. Prey
species are located by sight. Fishing perches are typically one to two metres above the water
surface. Nests are situated in treeholes or in the forks of large riparian trees almost
exclusively Diospyros mespiliformis - and egg laying takes place at the high flood season
with a peak in March. The chick remains dependent on the parents for several months,
probably until low water levels and greater fish concentrations make for a better chance of
surviving independently (Liversedge, 1980).
The Great Egret and Yellow-billed Egret feeds on fish which they catch by wading in shallow
water and static-hunting, spearing fish with the bill. Clear water may be an important feature
of this habitat. These birds do exploit the availability of fish at the `Barbel runs' that usually
take place from July to September in the Panhandle. Breeding may be linked to this
phenomenon and water flows (see 3.9.2).
Links to flow
During the day, Pel's Fishing-Owl roosts in large riverine trees, usually in the darkest spot in
the territory if there is inadequate cover and they are visible, they are mobbed by other
birds (in such circumstances they may be attacked and injured by African Fish-Eagles).
Favoured fishing perches are between one and two metres above the water surface.
Pel's Fishing-Owl lays its eggs during the high flood season, with a peak in March in the
Okavango Panhandle (Site 6) further downstream where flood levels peak later, eggs are
laid later (June). The chick remains dependent on the parents for several months, probably
25
EFA Botswana Birds
until low water levels and greater fish concentrations make for a better chance of surviving
independently (Liversedge, 1980).
Great and Yellow-billed egrets move in response to flooding, to areas of shallow water where
they can wade and catch fish floodplains are their prime areas, but margins of channels
and other waterbodies, where there is a shallow zone, are also utilised. Breeding of both
species is linked to water flows (see 3.9.3).
Indicator 3 Piscivores and invertebrate feeders in isolated pools
Main characteristics of indicator
These indicator species are directly flow-dependent because their lifestyles are dependent
on inundation of floodplains and recession of water later. These species mainly wade in the
shallow waters of the floodplains to get their food (small fish and invertebrates), or swim in
shallow isolated pools of open water on the floodplains when feeding. They are indicators of
floodplain health in terms of production of fish and invertebrates.
The characteristic and representative species of this indicator are listed in the table below.
Indicator 3 Piscivores of shallow water and lagoons
General species
Small herons and egrets, pelicans, storks, snipe,
lapwings, sandpipers, gallinules, moorhens, rails
and crakes
Representative species
Great White Pelican Pelecanus onocrotalus
Squacco Heron Ardeola ralloides
Little Egret Egretta garzetta
Red-billed Teal Anas erythrorhyncha
Hottentot Teal Anas hottentotus
Life cycle attributes
The Great White Pelican is highly opportunistic and occurs in large numbers at the best
fishing sites in the Okavango system (and beyond). It does not utilise the upper, nutrient-poor
reaches of the Delta, but prefers the distal ends of distributaries which are more productive.
For example, when Lake Ngami flooded in June 2004 for the first time in over a decade, it
was soon inhabited by Great White Pelicans, the numbers of which peaked at 5,200
individuals in December 2004 (Hancock et al., 2005). Since each adult pelican needs
approximately 1 kilogram of fish daily, for a few months over 5 tonnes of fish were being
consumed every day, mostly Schilbe intermedius, Marcusenius macrolepidotus and Clarias
gariepinus. Apart from Lake Ngami, the Great White Pelican also exploits drying lagoons
along the Boteti, Thamalakane and lower Boro, for example at Site 8 usually these are
drying by April/May before the new incoming floods, and this is the time that the Great White
Pelican breeds. It does not breed anywhere in the Okavango, although the `normal' flooding
of the Okavango system is crucial for these birds since they breed in the Nata River delta in
northern Sua Pan (350 kilometres to the east) and commute to the drying pools at the distal
end of the Okavango on a daily basis to catch fish to feed their young. This is an
energetically expensive undertaking and depends on the existence of `fish traps' in the form
of drying pools on floodplains or in river channels. The newly fledged pelicans from the Nata
Sanctuary must also make a 350 kilometre `maiden flight' to the Okavango where the
existence of a surfeit of fish is essential to their independence and immediate survival (see
McCulloch, 2008).
26
EFA Botswana Birds
The Squacco Heron feeds on small fish and aquatic invertebrates in a variety of situations in
the Okavango Delta, but is only known to breed at a few localities viz. Gadikwe Lediba, Boro
floodplain, Gomoti headwaters in Xou Lediba, Lake Ngami (when suitable conditions prevail)
(Tyler and Hancock, 2006). The only regularly used heronry is at Gadikwe Lediba near Site
7; breeding is mostly opportunistic and it is not known what factors trigger its onset, but it
seems to be a combination of good, late rains and early incoming floodwaters.
Little Egrets are opportunistic and exploit suitable feeding conditions on flooding or receding
floodplains; they are also one of the species active at Barbel runs, and occur in globally
significant numbers at Lake Ngami when it has water. They breed at a few traditional
heronries e.g. Gadikwe Lediba (Tyler and Hancock, 2006), usually around September, and it
is not known what factor(s) trigger breeding.
The ducks and geese, typified by the two teal species, prefer the nutrient rich waters of the
distal end of the Delta where they can reach high numbers. They are highly mobile and move
around extensively in search of these optimal conditions. Tyler (2001) found more Red-billed
Teal on the Thamalakane and Boteti Rivers than elsewhere in the Okavango Delta.
Douthwaite (1979) observed over 13,000 at Lake Ngami during the summer of 1979, vastly
more than recorded in the remainder of the Okavango Delta at any other time.
These species both prefer the nutrient-rich waters of the distal Okavango distributaries.
Links to flow
The feeding, and particularly the breeding of the Great White Pelican is linked to the
availability of `fish traps' in the distal reaches of the Okavango distributaries `normally'
these are present during April/May when the pelicans have large chicks to feed at the only
Botswana breeding site in the Nata Sanctuary. If this synchronised system is disrupted, the
species might no longer be able to breed in Botswana.
The Squacco Heron and Little Egret seem dependent on inundation and drying of floodplains
for feeding, but the importance of changes in the flow regime to these species is not clear,
except for the following - floodplains that are regularly flooded annually become less
productive for these birds than those that are dry for a period and then flood this is because
when dry, the floodplains are usually heavily grazed by herbivores which deposit significant
quantities of nutrients back into the system in the form of dung and urine.
The ducks move to the most productive parts of the Okavango system, which are generally
nutrient-rich areas that are frequently but not permanently inundated. During the 1990s when
the Boro outflow was very low, the Thamalakane and Boteti Rivers were dry most of the time.
During this period, Lake Ngami was also dry. These areas did not support any White-backed
ducks; once water flow increased and there were changes in the distribution of water in the
Delta, the southern reaches of the Delta and Lake Ngami held globally significant populations
of these two species. Changes in flows will therefore affect tens of thousands of individual
birds.
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EFA Botswana Birds
Indicator 4 Specialist feeders on floodplains, receding waters
Main characteristics of indicator
These indicator species are floodplain specialists that are dependent on the recession of
floodwaters for feeding and breeding. Diminution of floodplain extent, or changes in the
timing of wetting or drying of floodplains can disrupt breeding. The Okavango supports
globally significant populations of both Wattled Cranes and Slaty Egrets. The largest single
population of Wattled Cranes in the world is found in the Okavango Delta (1,300, about 18%
of the global population) (Motsumi and Hancock, 2004). The global population of Slaty Egrets
is estimated at 4,000 individuals (Wetlands International, 2002), of which about 85% occur in
the Okavango Delta.
The characteristic and representative species of this indicator are listed in the table below.
Indicator 4 Specialist feeders on floodplains, receding waters
General species
African Openbill, Wattled Crane, herons and egrets
Representative species
African Openbill Anastomus lamelligerus
Wattled Crane Bugeranus carunculatus
Slaty Egret Egretta vinaceigula
Life cycle attributes
The African Openbill is a specialist feeder on molluscs (Pina occidentalis, Lanistes sp.) on
shallow floodplains and channel margins these it finds by touch, by probing in water no
deeper than its legs are long. It is believed to move widely throughout the Delta in search of
optimal feeding conditions, which exist in the Panhandle in April as the adjacent floodplains
are inundated, and moving progressively south-eastwards following the floods. Peak
numbers along the Thamalakane River are found in early summer (November to January) as
water reaches its lowest level, exposing the molluscs. The molluscs are highly productive
and support thousands of openbills (there are no population estimates for this species in the
Okavango, although >1% of the global population is found here); any changes in waterflow
that affect these molluscs will impact on the openbills.
There is only one known breeding site in the Okavango Delta (apart from a small
opportunistic breeding colony at Lake Ngami), at Lediba la dinonyane, where almost 1,000
pairs nest regularly during September this is the largest known site in the Okavango basin.
It is situated in a lagoon, on Ficus verruculosa islands, where water levels do not vary
greatly. During September, the Okavango floodwaters throughout the Delta would be waning,
making rich feeding grounds available to this species birds commute considerable
distances between these feeding areas and the breeding site.
The Wattled Crane feeds on rhizomes, roots and bulbs of sedges, primarily Eleocharis spp.
and Bento (2002) has shown clearly how they follow receding floodplain margins where
Eleocharis is becoming water stressed and transferring food reserves to its underground
bulbs the cranes are still able to probe into the not-yet-hard mud in this zone to get the
bulbs. In its feeding, this species is therefore entirely dependent on receding floodwaters.
Breeding pairs are territorial and do not move much, so that their food requirements need to
be met in a relatively small area; prime territories are along the Jao/Boro floodplains.
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EFA Botswana Birds
Breeding is also confined to floodplains.
The Slaty Egret is another floodplain specialist (Hancock et al., 2005) since it feeds
exclusively in shallow floodplains with short, sparse emergent vegetation. It hunts by sight
and needs a fairly open water surface and good clarity of water to see the small fish (up to
10cm in length) and invertebrates that it eats. As with the Wattled Crane, higher flood levels
with more extensive flooding would create more suitable habitat for this species.
The breeding of this species is also relevant and is described below.
Links to flow
The African Openbill is totally dependent on receding waters on floodplains and channels to
enable it to access its specialised diet of a few, but prolific, mollusc species the molluscs in
turn are probably also dependent on waterflows. Since there is a distinct flood pulse of water,
the openbills are able to follow this, and find suitable areas that vary spatially and temporally;
suitable feeding areas are always available somewhere in the Okavango at any time. The
breeding of this species coincides with the period when the Okavango floodwaters are
generally receding.
The feeding of Wattled Cranes is closely linked to receding floodwaters, which led Bento
(2002) to implicate hydrological changes in the Zambezi Delta in the decline of the crane
population there. Waterflows that affect the amount of the cranes' preferred food species
(e.g. Eleocharis spp.) may also impact negatively on the birds.
The Slaty Egret feeds exclusively on shallow floodplains, and higher flow levels would make
more of this habitat available. Conversely, lower levels mean less suitable habitat.
Indicator 5 Specialist feeders in water lily-covered inlets
Main characteristics of indicator
These indicator species are highly specialised, having even evolved long toes to enable
them to walk on the floating aquatic vegetation that is their preferred habitat.
The characteristic and representative species of this indicator are listed in the table below.
Indicator 5 Specialist feeders in water lily-covered inlets
General species
Jacanas and gallinules, pygmy-geese
Representative species
African Jacana Actophilornis africanus
Lesser Jacana Microparra capensis
Allen's Gallinule Porphyrio alleni
Life cycle attributes
All three indicator species are closely associated with water lilies, particularly Allen's
Gallinule which in addition to eating aquatic invertebrates, feeds on developing water lily
seed heads. The two jacanas use water lilies as feeding platforms but eat exclusively
invertebrates they occupy slightly different niches because the Lesser Jacana actually
prefers a cover of Potamogeton thunbergi.
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EFA Botswana Birds
Allen's Gallinule is liberated from the water lily covered inlets during the breeding season
when it nests in floodplains and flooded grasslands, but the jacanas build floating nests of
vegetation among the water lilies.
Links to flow
These indicators are likely to be affected indirectly by changes in water flow, unlike some
others which will be physically displaced by, for example, high water flows. Drying out of
lagoons or inlets, which will affect the productivity of Nymphaea, will diminish the habitat
available for these species. Similarly, the time taken by waterlilies to regenerate will influence
the time taken by these birds to recolonise new habitat.
Indicator 6 Specialist feeders in riverine fruit trees
Main characteristics of indicator
These indicator species are indirectly affected by changes in water flow any changes to
their preferred fruiting trees in the riparian habitat will affect their numbers. They are likely to
be good indicators of changes to this important habitat.
The characteristic and representative species of this indicator are listed in the table below.
Indicator 6 Specialist feeders in water lily-covered inlets
General species
Parrots, starlings, bulbuls/greenbuls
Representative species
African Green-Pigeon Treron calvus
Black-collared Barbet Lybius torquatus
Burchell's Starling Lamprotornis australis
Life cycle attributes
The African Green-Pigeon and Black-collared Barbet in the Okavango are confined to
riparian forest along the waterways, where they feed on the fruits of the Strangler Fig, African
Ebony (Diospyros mespiliformis) and Bird Plum (Berchemia discolour), among others. They
usually nest in the same habitat, not far from water; the Black-collared Barbet in particular is
quite sedentary.
Burchell's Starling has a wider habitat tolerance than the preceding species, but like them,
feeds on fruiting riparian trees. Interestingly, they roost in Phragmites reedbeds in large
numbers and this may be an important component of their habitat that could be affected by
changes in water flow.
Links to flow
This group of indicator species are likely to be affected indirectly by changes in water flow
dying off of the riparian vegetation after prolonged dry periods such as occurred along distal
channels during the low flows of the 1990s, reduced prime habitat for these species through
a reduction in their food supply.
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EFA Botswana Birds
Indicator 7 Breeders in reedbeds, floodplains
Main characteristics of indicator
These indicator species are confined to breeding in reedbeds along watercourses or in the
floodplains themselves.
The characteristic and representative species of this indicator are listed in the table below.
Indicator 7 Breeders in reedbeds, and on floodplains
General species
Weavers, Bishops, Widowbirds, Whydahs, Prinias,
Cisticolas, Warblers, Gallinules, Crakes, Herons,
Egrets
Representative species
Weavers Ploceus spp.
Slaty Egret Egretta vinaceigula
Rufous-bellied Heron Ardeola rufiventris
Wattled Crane Bugeranus carunculatus
Life cycle attributes
Weavers breed during the summer months when climatic conditions result in an abundance
of food to feed chicks. The breeding sites in reeds are however influenced by floods the
reeds must be standing in water to be suitable.
Randall and Herremans (1994) described the breeding of the Slaty Egret in the Okavango
Delta, and found that they breed in Phragmites reedbeds in April/May just before the
incoming floodwaters peak. During the 2004/5 baseline survey (Hancock et al., 2005), Slaty
Egrets were also found breeding at this time, but in Phoenix reclinata islands. Reedbeds
previously used by this species had been burnt and had not recovered due to a low flood
cycle; low flood regimes allow greater access to people and the proliferation of
anthropogenic fires (and reed-cutting), to the detriment of Slaty Egrets. (Prolonged low flows
could also adversely affect Phoenix reclinata which thrives in permanently wet areas, on
termite mounds).
The ecology of the Rufous-bellied Heron is quite similar to that of the Slaty Egret, and they
breed together in the same reedbeds and Phoenix palm islands. They bred at peak flood
levels in the reedbed documented by Randall and Herremans (1994). According to Tarboton
et al. (1987), in South Africa egg-laying is to some extent opportunistic, according to flood
levels.
The Wattled Crane breeds on floodplains; the nest is a mound of vegetation standing in
about 75cm of water. Breeding takes place during winter, with egg-laying starting during July
so that most pairs are incubating during August. There does not appear to be any differential
in laying and hatching dates between the upper and lower reaches of the Delta despite the
time difference between flooding these areas (see Hancock, 2003); this refutes the
suggestion that the birds nest on receding floodwaters. Young cranes hatch at a time
(September) when the Okavango floodwaters are at their lowest throughout the Delta
whether this coincides with maximum food availability is not clear since a high proportion of
the diet of young cranes is insects.
During high flood years, when the flooded areas are more extensive, there may be more
suitable habitat available for breeding (only a small percentage of the population bred
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EFA Botswana Birds
between 6 and 16% in 2001, 2002 and 2003 - when flood levels were low). See also
Douthwaite (1974) who found 40% of the pairs breeding during a `normal' year and only 3%
in a year of negligible flooding conditions, on the Kafue Flats.
Links to flow
Reedbeds used by weavers for breeding are influenced by the onset of the flood season, its
magnitude and the duration.
Lower water levels mean less suitable breeding habitat for the Slaty Egret there is easier
access for people into the Delta, with a resulting increase in fires which destroy the species
breeding habitat, Phragmites reedbeds. A combination of fire and decreased water level is
fatal to Phragmites. Breeding is timed to the peak flood in late April/May and alteration of the
timing may affect this activity; the same applies to the Rufous-bellied Heron.
Wattled Crane breeding takes place on shallowly inundated floodplains and should these dry
our prematurely (before September), the nests would be exposed to greater predation.
Higher floods may make more areas of suitable breeding habitat available. Unseasonal high
water levels i.e. while the birds are incubating during July/August, may result in inundation of
nests. Altered distribution of floodwaters, with the Jao/Boro system receiving less water,
could adversely affect cranes because this is currently their core range, and the eastern half
is protected within Moremi Game Reserve.
Indicator 8 Breeders in riverine overhanging trees
Main characteristics of indicator
These indicator species are colonial breeders requiring overhanging vegetation for nest
safety or for fledglings vacating the nest to escape danger.
The characteristic and representative species of this indicator are listed in the table below.
Indicator 8 Breeders in riverine overhanging trees
General species
Weavers, Herons, Cormorants, Darters
Representative species
African Darter Anhinga rufa
Reed Cormorant Phalacrocorax africanus
Life cycle attributes
The African Darter nests colonially on trees (or reeds) standing in water, usually in
association with Reed Cormorants this takes place during June and July, so this is the time
that the availability of fish is most important (the species is exclusively piscivorous). Several
sites regularly used at JereJere Lediba, Xakanaxa Lediba, upper Phillipo Channel, east of
Xigera these all comprise trees such as Syzygium sp. standing in permanent water. When
the darter nestlings are disturbed, they vacate the nest and dive into the water for safety,
later clambering back up.
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EFA Botswana Birds
The Reed Cormorant uses several traditional breeding sites in the Okavango at JereJere
Lediba, near Xigera, at Xakanaxa Lediba and on the Upper Phillipo Channel; however, the
species will also breed opportunistically e.g. at Lake Ngami when conditions are suitable.
Nesting colonies usually active during July in the Delta i.e. at peak flood, but may nest after
peak flood at Lake Ngami i.e. October/November.
Links to flow
Both these species use a few traditional breeding sites in the Okavango; however, the
species will also breed opportunistically e.g. at Lake Ngami when conditions are suitable.
Nesting colonies are usually active during July in the Delta i.e. at peak flood, but may nest
after peak flood at Lake Ngami i.e. October/November. When their nestlings are disturbed,
they vacate the nest and dive into the water for safety nesting trees are thus always in
permanent water. There may be a link between the timing of breeding with the onset of the
Barbel run in the Panhandle.
Indicator 9 Breeders on banks
Main characteristics of indicator
These indicator species are colonial breeders requiring vertical banks for nest holes these
sites are at a premium in the flat Okavango or the grassy banks for nest sites and fledgling
development.
The characteristic and representative species of this indicator are listed in the table below.
Indicator 9 Breeders on banks
General species
Kingfishers, Bee-eaters, Lapwings
Representative species
Southern Carmine Bee-eater Merops nubicoides
White-fronted Bee-eater Merops bullockoides
Pied Kingfisher Ceryle rudis
Life cycle attributes
The Southern Carmine Bee-eater is an intra-African migrant that arrives in the Okavango
region in relatively large numbers in August/September to breed colonially in the steep banks
of the Okavango River along the Panhandle in Shakawe, downstream of Drotsky's Cabins
and at Red Cliffs; they also bred elsewhere lower down the Delta at Four Rivers, Shinde and
Xakanaxa these sites are atypical and are on flat ground. By December, the adults and
young disperse throughout Southern Africa before migrating northwards again during March.
During low flow cycles, this species establishes more colonies in dry floodplains (see Muller
and Hancock, 2007) but when these areas are again flooded, they are of course abandoned
by the bee-eaters. The birds forage for insects over grasslands and woodlands away from
the Okavango waterways, and this activity is independent of water flows.
The White-fronted Bee-eaters are resident in the Okavango Panhandle, and are sedentary,
seldom moving more than 3 to 7 kilometres from their breeding sites in Shakawe and
elsewhere along the Okavango Panhandle. They breed in early summer together with the
Carmine Bee-eaters, apparently to avoid rising floodwaters following summer rains (J
Drotsky, pers. comm.).
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EFA Botswana Birds
The Pied Kingfisher breeds throughout the year, but with a peak in September, in holes
excavated in the banks of the Okavango River (this is when the water level is lowest and
most banks are exposed). Optimal nesting habitat is found at Site 6, but further downstream
where the terrain is flatter, they nest at the base of termite mounds near the water's edge.
Links to flow
Carmine Bee-eater colonies along the Zambezi River were flooded by construction of the
Kariba and Cahora Bassa Dams (Barnes and Herremans, 1997).
Early, high flooding i.e. during September, will destroy the nests of all three of these indicator
species. Flooding during late summer (March/April) may be needed to keep the Okavango
River banks steep and free of grass and other vegetation that could conceal predators.
Indicator 10 Breeders on emergent rocks, sandbanks, islands
Main characteristics of indicator
These indicators, especially the African Skimmer, have a very narrow breeding niche, nests
being confined to low sandbanks and/or sandy islands with some vegetation nearby for chick
concealment during disturbances. The Zambezi, Chobe and Okavango Rivers are the main
breeding areas for the African Skimmer in Southern Africa this Near Threatened species is
extinct as a breeding bird in South Africa.
The characteristic and representative species of this indicator are listed in the table below.
Indicator 10 Breeders on sandbars, islands
General species
African Skimmer, Sandpiper, Thick-knees
Representative species
African Skimmer Rynchops flavirostris
Water Thick-knee Burhinus vermiculatus
Life cycle attributes
The African Skimmer is a partial intra-African migrant, arriving in the Okavango Panhandle in
June when the floodwaters are receding, but before sandbanks are exposed (Vial, 1995). It is
a highly specialised bird which feeds by flying low over open water trailing the lower
mandible in the water to detect small fish (its exclusive diet, mostly those <60mm). Species
taken in the Okavango include Tilapia spp., Barbus spp., Marcusenius macrolepidotus,
Herpestes odoe, Aplocheilichthys spp. and Petrocephalus catastoma (Paxton, unpubl. data).
Tracts of open water, free of all vegetation, are essential for this specialised method of
feeding to be successful.
Once sandbanks become exposed, during August/September (lowest flow period), this
species breeds i.e. low flow needed for breeding during `prolonged' low flow cycles (less
than a decade), other sites become available at Xigera Lagoon and on the middle Boro
River, and this has been important for the skimmer because the Panhandle sites are subject
to a lot of human disturbance. The sandbanks must have bare open sandy areas with some
vegetation nearby; when danger threatens the chicks vacate the nest scrape and hide in the
vegetation until danger has passed. Most chicks have fledged by November any
unseasonal increases in water level before this time would totally disrupt breeding. After
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EFA Botswana Birds
breeding, adult and young skimmers disperse southwards to the distal ends of the Okavango
at Chanoga (Site 8) and Lake Ngami these areas are more nutrient rich and may be
important for immature survival.
The Water Thick-knee has a more catholic diet than the skimmer, feeding on frogs and
tadpoles, crabs, aquatic beetles, insects and crustaceans which it finds along the water's
edge at night. It also breeds on sandbars like the skimmer, with a peak during October at the
time of lowest water levels.
Links to flow
The African Skimmer requires open unvegetated stretches of water with small, surface-
swimming fish, for its unique feeding method to be successful.
It needs exposed, bare sandbanks for breeding during the period August to November. If
water levels are high and sandbars are not exposed, it cannot commence breeding. If water
levels are low earlier, this will enable them to start breeding earlier - however, if water levels
increase during the period after breeding has commenced, breeding will be totally disrupted.
Regular inundation of the sandbanks, outside the skimmer breeding season, and the fresh
deposition of sand is necessary to prevent the breeding sites from becoming completely
vegetated, and therefore unsuitable for skimmers (and thick-knees) to breed (Aspinall, 2005).
Summary
The indicator species described above vary in the extent to which they will be affected by
changes in water flow. Generally, the better studied species e.g. Wattled Crane, African
Skimmer, Slaty Egret, seem to be more affected than others, but this is probably a factor of
the available knowledge.
Those species which depend on the Okavango water flows for both feeding and breeding are
more likely to be robust indicators since they will definitely be affected by the changes;
species that breed elsewhere may escape some of the negative impacts of changed water
flow. Conversely, bird species that will only be affected indirectly by having their food supply
altered will not be such good indicators since the effect of changed water flows will be more
complicated.
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EFA Botswana Birds
5
DATA COLLECTION AND ANALYSIS
Methods for data collection and analysis
This report is based on fieldwork on birds conducted during the period 2000 to the present,
and not on any specific work for this project. Previous fieldwork is summarized below:
Extensive aerial surveys of the whole Delta censusing Wattled Cranes, during 2001, 2002
and 2003. This was supported by groundwork monitoring breeding success of nesting pairs
Fieldwork gathering data for a baseline study of the Slaty Egret during 2004 and 2005.
AquaRap 2003 birds were surveyed at two of the sites relevant to this project (viz.
Shakawe and Xakanaxa) as well as at other sites, which provided the basis for selecting the
indicator species at these sites.
African Waterbird Census data these waterbird counts are conducted biannually (mid-
winter and mid-summer) throughout the Okavango Delta and provide detailed information on
the numbers and distribution of waterbirds which can be related to water flow levels. The
three sites for this project have been regularly surveyed in the past for some sites the
dataset spans almost two complete decades.
A summary of present understanding of the predicted responses of all bird
indicators to potential changes in the flow regime
The following tables summarise general responses of the indicator species to dry season
variables, flood season variables and the transition between flood and dry seasons. It must
be emphasised that these are general reponses as they are not area specific.
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EFA Botswana Birds
Indicator 1 (Piscivores of open water)
Table 5: Predicted response to possible changes in the flow regime of Piscivores of open water as an indicator in the Okavango River ecosystem
Confidence in
Question
prediction
number
Season
Possible flow change
Predicted response of indicator
(very low, low,
medium, high)
The low flows of the dry season will generally affect these birds positively
Onset is earlier or later
1
since fish will be more concentrated and water currents will be less, so an
Medium
than natural
early onset of the dry season will slightly improve their situation.
Dry
Lower dry season flows will be marginally better for these birds as it will be
2
Water levels are higher
Season
slightly easier to catch fish under these conditions, but the higher levels
Medium
or lower than natural
will be disadvantageous
Since the dry season is best for these birds in terms of ease of fishing, the
3
Extends longer than
Medium
natural
longer the dry season the better it will be for them.
The start of the flood season is the start of more difficult fishing conditions
Onset is earlier or later
for these birds due to greater amounts of water and increased velocity of
4
Medium
than natural
flow which will affect their ability to catch fish. Early onset will be less
favourable; a late onset would be beneficial.
These birds are not using the floodplain areas, so the changes in the area
Flood
5
Extent of inundated area flooded will not be relevant for them, except insofar as the floodplains are
Medium
season
the breeding grounds for fish (the prey base for this group)
The flood season is the time that these piscivores are under stress as it is
less easy for them to catch fish in the open waters - if the flood season
6
Flood season duration
Medium
were longer, this would affect them adversely, but only marginally so,
since they are quite adaptable.
Duration is longer or
The duration of the transition period will have no effect on these indicator
shorter than natural i.e. species
7
Transition
Low
2
hydrograph is steeper or
shallower
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EFA Botswana Birds
Indicator 2 (Piscivores of shallow water and lagoons)
Table 6: Predicted response to possible changes in the flow regime of Piscivores of shallow water and lagoons as an indicator in the Okavango
River ecosystem
Confidence in
Question
prediction
number
Season
Possible flow change
Predicted response of indicator
(very low, low,
medium, high)
Onset is earlier or later
The dry season is better for these birds which prefer the shallow waters at
1
Medium
than natural
this time - an earlier onset is slightly better for them
Lower dry season flows favour these birds significantly as fish are more
Dry
concentrated (this is the time of the barbel run and the herons and egrets
2
Water levels are higher
Medium
Season
or lower than natural
are the birds that capitalise on it) - there is also plenty of shallow water to
fish in. Higher dry season water levels will be slightly unfavourable.
Since these birds favour the shallow water prevailing during the dry
3
Extends longer than
Medium
natural
season, a longer dry season is better for them.
Onset is earlier or later
The onset of the flood season brings hard times for these birds, so an
4
Medium
than natural
early flood season would impact on them negatively
These birds are not using the floodplains for feeding so the extent to which
Flood
5
Extent of area inundated they are inundated is not relevant (except for the fact that their prey fish
Medium
season
are breeding on the floodplains)
6
Flood season duration
These birds are not using the floodplains so the length of time for which
they are inundated is not relevant
Medium
Duration is longer or
These birds are not affected by the duration of the transition period
shorter than natural i.e.
7
Transition
Low
2
hydrograph is steeper or
shallower
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EFA Botswana Birds
Indicator 3 (Piscivores and invertebrate feeders in isolated pools)
Table 7: Predicted response to possible changes in the flow regime of Piscivores and invertebrate feeders in isolated pools as an indicator in the
Okavango River ecosystem
Confidence in
Question
prediction
number
Season
Possible flow change
Predicted response of indicator
(very low, low,
medium, high)
Onset is earlier or later
The timing of the onset of the dry season will not affect this group of birds
1
Low
than natural
The water level during the dry season will not affect these birds
2
Water levels are higher
Dry
Low
or lower than natural
Season
These birds have the extent of their suitable habitat reduced during the dry
3
Extends longer than
season, as there is no water on the floodplains, so a longer dry season is
Medium
natural
a period of stress
An early start to the flood season would result in increased food availability
Onset is earlier or later
4
as the floodplains become inundated, thus relieving the stress of the dry
Low
than natural
season
Flood
5
season
Extent of area inundated The greater the area inundated, the more suitable habitat (Isolated pools)
will result when the floods dry out
Medium
6
Flood season duration
The longer the flood season the better for these birds because optimal
Medium
feeding conditions will persist longer
Duration is longer or
A quick transition will result in more fish being trapped on the floodplains,
shorter than natural i.e. and in the rapid concentration of invertebrates, and this will be good for
7
Transition
Medium
2
hydrograph is steeper or these birds
shallower
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EFA Botswana Birds
Indicator 4 (Specialist feeders on floodplains)
Table 8: Predicted response to possible changes in the flow regime of Piscivores and invertebrate feeders on floodplains as an indicator in the
Okavango River ecosystem
Confidence in
Question
prediction
number
Season
Possible flow change
Predicted response of indicator
(very low, low,
medium, high)
The timing of the onset of the dry season is important for these birds since
Onset is earlier or later
they need an adequate period of drying floodplains (when food availability
1
Medium
than natural
is at a peak) to build up condition before breeding - the earlier onset, the
Dry
better.
Season
The water level during the dry season will not affect these birds
2
Water levels are higher
Medium
or lower than natural
A long dry season, with dry floodplains, would be disadvantageous for
3
Extends longer than
Medium
natural
these birds since they depend on inundated floodplains
If the flood season started late this would not be good for these birds
Onset is earlier or later
because it would result in ideal feeding conditions being available for a
4
Medium
than natural
shorter period
Flood
season
5
Extent of inundated area The greater the area flooded, the better for these birds because they
High
would have more prime feeding habitat available
6
Flood season duration
Since these birds depend on the floodplain having some water, the longer
the flood season lasts the better
High
Duration is longer or
A gradual transition from flooded to dry would be good for these birds
shorter than natural i.e. because it would result in a slow sustained production of their food
7
Transition
High
2
hydrograph is steeper or
shallower
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EFA Botswana Birds
Indicator 5 (Specialist feeders In waterlily covered inlets)
Table 9: Predicted response to possible changes in the flow regime of Specialist feeders in waterlily covered inlets as an indicator in the Okavango
River ecosystem
Confidence in
Question
prediction
number
Season
Possible flow change
Predicted response of indicator
(very low, low,
medium, high)
Onset is earlier or later
The timing of the onset of the dry season is irrelevant for these birds
1
Medium
than natural
Dry
If dry season flows drop very low, waterlilies in extensive areas would die
2
Water levels are higher
Medium
Season
or lower than natural
out slightly reducing habitat for these species
The duration of the dry season is irrelevant for waterlilies and these birds
3
Extends longer than
Medium
natural
Onset is earlier or later
The timing of the onset of the flood season would not make any difference
4
Medium
than natural
to these birds
Flood
5
Extent of inundated area The greater the area inundated, the more widespread waterlilies would be High
season
and therefore there would be more available habitat for these birds
6
Flood season duration
A long flood season would favour the persistence of waterlilies and benefit Medium
these birds slightly
Duration is longer or
The duration of the transition period would be irrelevant for these birds
shorter than natural i.e.
7
Transition
High
2
hydrograph is steeper or
shallower
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EFA Botswana Birds
Indicator 6 (Specialist feeders in riverine fruit trees)
Table 10: Predicted response to possible changes in the flow regime of Specialist feeders in riverine fruit trees as an indicator in the Okavango
River ecosystem
Confidence in
Question
prediction
number
Season
Possible flow change
Predicted response of indicator
(very low, low,
medium, high)
NB This indicator depends on riparian fruit trees which are not significantly
Onset is earlier or later
influenced by annual changes in any of the variables listed only longer
1
Medium
than natural
term (>10 years), low flows on the seasonally flooded areas (Site 7) and in
Dry
the distal parts of the delta (Site 8)
Season
Not relevant for this indicator
2
Water levels are higher
Medium
or lower than natural
Not relevant for this indicator
3
Extends longer than
Medium
natural
Onset is earlier or later
Not relevant for this indicator
than natural
4
Medium
synchronisation with rain
may be changed
Flood
If flooding of the floodplains is more extensive, more island tree copses
season
5
Extent of inundated area will be reached by the floodwater resulting in increased fruit availability for
Low
these birds.
6
Flood season duration
There seems to be an optimal 3 month flood duration period needed by
Low
fruit trees for fruiting - more or less than this is detrimental
Duration is longer or
Not relevant for this indicator
shorter than natural i.e.
7
Transition
Medium
2
hydrograph is steeper or
shallower
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EFA Botswana Birds
Indicator 7 (Breeders in reedbeds and floodplains)
Table 11: Predicted response to possible changes in the flow regime of Breeders in reedbeds and floodplains as an indicator in the Okavango
River ecosystem
Confidence in
Question
prediction
number
Season
Possible flow change
Predicted response of indicator
(very low, low,
medium, high)
Onset is earlier or later
The timing of the onset of the dry season will not affect these birds in any
1
Medium
than natural
way
Dry
Water levels during the dry season will not affect these birds in any way
2
Water levels are higher
Medium
Season
or lower than natural
Duration of the dry season will not affect these birds
3
Extends longer than
Medium
natural
Breeding of birds in this Indicator Group is governed by the floods and the
Onset is earlier or later
4
onset of the floods often triggers breeding - an early onset of floods will
Low
than natural
result in early breeding and therefore higher productivity
Flood
A larger inundated area will result in potentially more available breeding
5
season
Extent of inundated area sites, notwithstanding that the traditional breeding sites for these birds are Medium
at specific locations
6
Flood season duration
A longer flood season would enable these birds to complete their whole
Medium
breeding cycle before the waters dried up
Duration is longer or
A rapid transition could result in breeding sites being left high and dry, with
shorter than natural i.e. unfledged chicks exposed to predation
7
Transition
Medium
2
hydrograph is steeper or
shallower
43
EFA Botswana Birds
Indicator 8 (Breeders in riverine overhanging trees)
Table 12: Predicted response to possible changes in the flow regime of Breeders in riverine overhanging trees as an indicator in the Okavango
River ecosystem
Confidence in
Question
prediction
number
Season
Possible flow change
Predicted response of indicator
(very low, low,
medium, high)
Onset is earlier or later
Timing of the onset of the dry season would not affect these birds
1
Medium
than natural
Dry
Water levels during the dry season would not affect these birds
2
Water levels are higher
Medium
Season
or lower than natural
Duration of the dry season is irrelevant for these birds
3
Extends longer than
Medium
natural
Onset is earlier or later
Early flood season onset coincides with the breeding season of some of
than natural
these birds, and triggers breeding in others - early floods will generally
4
Medium
synchronisation with rain provide more time for breeding
may be changed
Flood
5
season
Extent of inundated area A greater inundated area will produce more potential breeding sites where Medium
trees overhang water
These birds need a long flood period in which to complete their whole
6
Flood season duration
breeding cycle
Medium
Duration is longer or
A quick transition could leave nesting birds exposed to predation, and this
shorter than natural i.e. would obviously be disadvantageous
7
Transition
High
2
hydrograph is steeper or
shallower
44
EFA Botswana Birds
Indicator 9 (Breeders on banks)
Table 13: Predicted response to possible changes in the flow regime of Breeders on banks as an indicator in the Okavango River ecosystem
Confidence in
Question
prediction
number
Season
Possible flow change
Predicted response of indicator
(very low, low,
medium, high)
Onset is earlier or later
Timing of dry season onset not relevant to this indicator
1
Medium
than natural
These birds breed at the end of the dry season, and the lower the flows at
this time, the more banks will be exposed and the better will be their
2
Water levels are higher
Dry
Medium
or lower than natural
breeding success
Season
A prolonged dry season will enable these birds to complete their breeding
3
Extends longer than
cycle before the floods arrive
Medium
natural
If the floods arrive before the birds finish breeding this will disrupt breeding
Onset is earlier or later
4
to a variable extent
Medium
Flood
than natural
season
5
Extent of inundated area
The extent of inundation is not relevant to these birds
Medium
6
Flood season duration
The duration of the flood season is not relevant to this indicator
Medium
Duration is longer or
The duration of the transition period is not relevant to this indicator group
shorter than natural i.e.
7
Transition
High
2
hydrograph is steeper or
shallower
45
EFA Botswana Birds
Indicator 10 (Breeders on emergent rocks, sandbanks and islands)
Table 14: Predicted response to possible changes in the flow regime of Breeders on emergent rocks, sandbanks and islands as an indicator in the
Okavango River ecosystem
Confidence in
Question
prediction
number
Season
Possible flow change
Predicted response of indicator
(very low, low,
medium, high)
If the dry season starts earlier, these birds will actually breed earlier -
Onset is earlier or later
1
African Skimmers arrive in the Panhandle (site 6) before the sandbanks
High
than natural
are exposed, and wait for them to appear
Low dry season flows result in more sandbanks being exposed for these
Dry
2
Water levels are higher
birds to breed on; however when flows are very low, sandbanks become
High
Season
or lower than natural
encroached with vegetation and unsuitable
The dry season must extend beyond a certain minimum period (90 days)
3
Extends longer than
so that these birds can complete their breeding cycle if it is longer than
High
natural
this, it will be favourable for the birds
If the flood season starts before the end of November, this would be
Onset is earlier or later
4
disastrous for these birds as they would not have finished breeding by
High
than natural
then
Flood
5
season
Extent of inundated area If the floodplains are not inundated, then the food supply for these birds
High
will be negatively affected
6
Flood season duration
Floods must be of reasonable duration to ensure that fish (the food source High
for some of the birds in this indicator) breed and maintain a sufficient level
Duration is longer or
Not relevant for this indicator
shorter than natural i.e.
7
Transition
Hgh
2
hydrograph is steeper or
shallower
46
EFA Botswana Birds
7. CONCLUSION
Some of the indicators appear useful, particularly those species for which detailed studies
have been undertaken in the Okavango Delta specifically. These species have been chosen
as indicators based on facts related to the effect of changing hydrological conditions on their
populations. If similar data existed for species such as the African Openbill in the Okavango
system, the usefulness of this species as an indicator would be enhanced. If species have
been well studied elsewhere e.g. Reed Cormorant, African Darter, this does not assist much
to predict their response to changes in flow regimes.
Notwithstanding the above, it is felt that the following 10 species are going to be the most
useful bird indicators:
Reed Cormorant
African Darter
Pied Kingfisher
Great White Pelican
African Openbill
Slaty Egret
Wattled Crane
Southern Carmine Bee-eater
African Skimmer
Red-billed Teal
Historical data on the numbers and distribution of the indicator birds, such as exists, was
useful in substantiating some of the predictions relating to those species.
47
EFA Botswana Birds
8. REFERENCES
Aspinall, T. 2005. African Skimmers on the Okavango River, 2004. Babbler 46: 18-24.
Barnes, KN and Herremans, M. 1997. Carmine Bee-eater. In: Harrison, JA et al. (eds.). Atlas
of Southern African Birds. Vol. 1: 666. BirdLife South Africa, Johannesburg.
Beilfuss, R, Bento, C, Hancock, P, Kamweneshe, B, McCann, K, Morrison, K and Rodwell, L.
2003. Water, wetlands and Wattled Cranes: A regional monitoring and conservation program
for Southern Africa. In: Bernard, T, Mosepele, K and Ramberg, L. (eds). 2003. Environmental
Monitoring of Tropical Wetlands. Proceedings of a Conference held in Maun, Botswana, 4-8
December, 2002. Okavango Report Series No. 1. Harry Oppenheimer Okavango Research
Centre.
Bento, CM. 2002. The Status and Prospects of Wattled Cranes Grus carunculatus in the
Marromeu Complex of the Zambezi Delta. MSc. thesis. University of Cape Town, South
Africa.
Douthwaite, RJ. 1974. An endangered population of Wattled Cranes. Biological Conservation
6: 134-142.
Douthwaite, RJ. 1979. Aerial survey of the eastern Okavango Delta, Lake Ngami and
Ntwetwe Pan for cranes, ducks and other waterbirds, 1 2 February, 1979. Report to
DWNP.
Douthwaite, RJ. 1982. Changes in Pied Kingfisher (Ceryle rudis) feeding related to
Endosulphan pollution from Tsetse Fly control operations in the Okavango Delta, Botswana.
Journal of Applied Ecology 19: 133-141.
Gibson, D St. C, Craig, GC, McCann, K and Hancock, P. 2002. Aerial survey of Wattled
Cranes Bugeranus carunculatus in the Okavango Delta, Botswana. Babbler 40: 3-14.
Hancock, P. 2003. Crane research and monitoring in the Okavango Delta 2002. Babbler
42: 4-9.
Hancock, P, Oake, K, Tyler, SJ and Brewster, CA. 2005. Monitoring waterbirds at Lake
Ngami an Important Bird Area. June, 2004 to January, 2005. BirdLife Botswana internal
report, 53 pp.
Hancock, P, Mpofu, Z, Tyler, SJ and Meyer, T. 2005. A Baseline Survey of the Slaty Egret in
the Okavango Delta Ramsar Site, Botswana. Report prepared by BirdLife Botswana for the
Okavango Delta Management Plan.
Hancock, P, Muller, M and Tyler, SJ. 2007. Inventory of Birds of the Okavango Delta Ramsar
site. Babbler 49: 3-29.
Liversedge, TN. 1980. A study of Pel's Fishing Owl Scotopelia peli Bonaparte 1850 in the
`Pan Handle' region of the Okavango Delta, Botswana. Proc. IV Pan-Afr. Orn. Congr. 291-
299.
McCulloch, G. 2008. Going the Distance: the great flight of the Pelican. Africa Birds and
Birding 13 (1): 36-41.
48
EFA Botswana Birds
Motsumi, S, Hancock, P, Borello, WD, Tyler, SJ and Evans, SW (eds.) 2003. Botswana
Wattled Crane Bugeranus carunculatus Action Plan. Final Workshop Report. BirdLife
Botswana and BirdLife South Africa.
Motsumi, S and Hancock, P. 2004. Aerial survey of Wattled Cranes in the Okavango Delta,
August, 2003. Babbler 44: 44-51.
Muller, M and Hancock, P. 2007. Linyanti Swamps-Chobe River Important Bird Area
Monitoring Report 2007. Babbler Special Supplement No. 2. BirdLife Botswana, Maun. 66
pp.
Penry, H. 1994. Bird Atlas of Botswana. University of Natal Press, Pietermaritzburg. 316 pp.
Randall, R and Herremans, M. 1994. Breeding of the Slaty Egret Egretta vinaceigula along
the Boro River in the central Okavango Delta (Botswana). Ostrich 65: 39-43.
Tarboton, WR, Kemp, MI and Kemp, AC. 1987. Birds of the Transvaal. Transvaal Museum,
Pretoria.
Tyler, SJ and Bishop, D. 1998. Important Bird Areas of Botswana. In: The Important Bird
Areas of Southern Africa. Barnes, KN (ed.) pp. 333-354. BirdLife South Africa,
Johannesburg.
Tyler, SJ. 2001. A review of waterbird counts in Botswana, 1991-2000. Babbler Special
Supplement No. 1. BirdLife Botswana, 94 pp.
Tyler, SJ and Hancock, P. 2006. Heronries in Botswana. Babbler 48: 19-39.
Vial, C. 1995. The influence and effects of disturbance on the distribution, nest ecology,
breeding biology and reproductive success of the African Skimmer Rynchops flavirostris in
the Panhandle of the Okavango Delta. Unpubl. MS, Conservation International, Maun.
Wetlands International. 2002. Waterbird Population Estimates Third Edition. Wetlands
International Global Series No. 12, Wageningen, The Netherlands.
Wright, D and Hancock, P. 2008. Pel's Fishing-Owl Scotopelia peli falls prey to Verreaux's
Eagle-Owk Bubo lacteus in the Okavango Delta. Gabar 19 (2): 73-74.
49
EFA Botswana Birds
APPENDIX A: FULL DESCRIPTIONS OF INDICATORS
Country and Site Relevance
Representative Species
Indicators
Angola Namibia Botswana Angola
Namibia
Botswana
Comments
Reed Cormorant,
Fish Eagle, Osprey,
Fish-Eagle, Reed
Predominantly feed on fish
Piscivores of
African Darter,
King fishers,
Cormorant, African Darter, available in main river system or
open water
Yes
Yes
Yes
kingfishers
cormorants, Darters
Pied Kingfisher
adjoining pools.
Piscivores of
Pels Fishing Owl,
Need overhanging trees and
Pel's Fishing-Owl, larger
shallow water & Yes
Yes
Yes
Larger herons/egrets
Larger Herons,
sandbanks for breeding and
herons/egrets
lagoons etc.
Larger Egrets, Terns
feeding.
Smaller herons,
Smaller Egrets,
Piscivores and
Little Egret, Black
Storks, Snipe,
Feed on fish-fry at receding
Great White Pelican,
invertebrate
Heron, Glossy Ibis,
Plovers, Lapwings,
water level times after spawning
Yes
Yes
Yes
Squacco Heron, Little
feeders,
Saddle-billed Stork,
Sandpipers,
in flood-plains, or fish trapped in
Egret, ducks and geese
isolated pools
Lapwings
Gallinules,
drying pools.
Moorhens, Rails,
Crakes
Feed on molluscs, frogs, fish or
Specialist
African Openbill,
African Openbill, Slaty
selective vegetation and
feeders on
Yes
Yes
Yes
Cranes, African
Openbill
cranes
Egret, Wattled Crane
organisms occurring in shallow
floodplains
floodplain situations
Specialist
Floodplain pools (rising and
feeders in
African Jacana African Jacana, Lesser
receding water levels) and lily-
Yes
Yes
Yes
African Jacana,
water-lily
Lesser Jacana
Lesser Jacana
Jacana, Allen's Gallinule
pad covered inlets. Essential for
covered inlets
feeding habitat
50
EFA Botswana Birds
Specialist
When riverine fruit trees are in
African Green Pigeon,
feeders in
fruit they are an important food
Yes
Yes
Yes
Turacos, bulbuls
Parrots, Turacos,
Black-collared Barbet,
riverine fruit
Bulbuls
source for a large variety of
Burchell's Starling
trees
birds
Weavers, Bishops,
Widowbirds,
Breeders in
Fan-tailed Widowbird,
Weavers, Slaty Egret,
Whydahs, Prinias,
Nesting habitat in reedbeds
reedbeds, and
Yes
Yes
Yes
weavers, bishops,
Rufous-bellied Heron,
cisticolas, Warblers,
lining river banks and islands.
on floodplains
herons/egrets
Wattled Crane
Gallinules Crakes,
Herons, Egrets
Breeders in
Colonial breeders or solitary
riverine
Herons, Cormorants, African Darter, Reed
nesters requiring over-hanging
Yes
Yes
Yes
Herons, Cormorants,
overhanging
Darters
Darters
Cormorant
vegetation for nest safety or
trees
fledglings vacating the nest
Kingfishers, Bee-
Require vertical banks for nest
Carmine Bee-eater, White-
Breeders on
eaters, Collared
holes or the grassy banks for
fronted Bee-eater, Pied
banks
Yes
Yes
Yes
White-fronted and
other Bee-eaters
Pratincoles,
nest sites and fledgling
Kingfisher
Lapwings
development
Breeders on
Rock Pratincoles,
Totally dependent on emerged
emergent rocks,
African Skimmer,
African Skimmer, Water
rocks, sandbars and islands in
Yes
Yes
No
Rock Pratincoles,
sandbars and
African Skimmer
Sandpipers, Thick-
Thick-knee
the main river for nesting
islands
knees
purposes
51
EFA Botswana Birds
The Okavango River Basin Transboundary Diagnostic Analysis Technical Reports
I
Diagnostic Analysis to establish a base of available
n 1994, the three riparian countries of the Okavango
scientific evidence to guide future decision making.
River Basin Angola, Botswana and Namibia agreed
The study, created from inputs from multi-disciplinary
to plan for collaborative management of the natural
teams in each country, with specialists in hydrology,
resources of the Okavango, forming the Permanent
hydraulics, channel form, water quality, vegetation,
Okavango River Basin Water Commission (OKACOM).
aquatic invertebrates, fish, birds, river-dependent
In 2003, with funding from the Global Environment
terrestrial wildlife, resource economics and socio-
Facility, OKACOM launched the Environmental
cultural issues, was coordinated and managed by a
Protection and Sustainable Management of the
group of specialists from the southern African region
Okavango River Basin (EPSMO) Project to coordinate
in 2008 and 2009.
development and to anticipate and address threats to
the river and the associated communities and
The following specialist technical reports were
environment. Implemented by the United Nations
produced as part of this process and form
Development Program and executed by the United
substantive background content for the Okavango
Nations Food and Agriculture Organization, the project
River Basin Trans-boundary Diagnostic Analysis
produced the Transboundary.
Final Study
Reports integrating findings from all country and background reports, and covering the entire
Reports
basin.
Aylward, B.
Economic Valuation of Basin Resources: Final Report to
EPSMO Project of the UN Food & Agriculture Organization as
an Input to the Okavango River Basin Transboundary
Diagnostic Analysis
Barnes, J. et al.
Okavango River Basin Transboundary Diagnostic Analysis:
Socio-Economic Assessment Final Report
King, J.M. and Brown,
Okavango River Basin Environmental Flow Assessment Project
C.A.
Initiation Report (Report No: 01/2009)
King, J.M. and Brown,
Okavango River Basin Environmental Flow Assessment EFA
C.A.
Process Report (Report No: 02/2009)
King, J.M. and Brown,
Okavango River Basin Environmental Flow Assessment
C.A.
Guidelines for Data Collection, Analysis and Scenario Creation
(Report No: 03/2009)
Bethune,
S.
Mazvimavi,
Okavango River Basin Environmental Flow Assessment
D. and Quintino, M.
Delineation Report (Report No: 04/2009)
Beuster, H.
Okavango River Basin Environmental Flow Assessment
Hydrology Report: Data And Models(Report No: 05/2009)
Beuster,
H. Okavango River Basin Environmental Flow Assessment
Scenario Report : Hydrology (Report No: 06/2009)
Jones, M.J.
The Groundwater Hydrology of The Okavango Basin (FAO
Internal Report, April 2010)
King, J.M. and Brown,
Okavango River Basin Environmental Flow Assessment
C.A.
Scenario Report: Ecological and Social Predictions (Volume 1
of 4)(Report No. 07/2009)
King, J.M. and Brown,
Okavango River Basin Environmental Flow Assessment
C.A.
Scenario Report: Ecological and Social Predictions (Volume 2
of 4: Indicator results) (Report No. 07/2009)
King, J.M. and Brown,
Okavango River Basin Environmental Flow Assessment
C.A.
Scenario Report: Ecological and Social Predictions: Climate
Change Scenarios (Volume 3 of 4) (Report No. 07/2009)
King, J., Brown, C.A.,
Okavango River Basin Environmental Flow Assessment
Joubert, A.R. and
Scenario Report: Biophysical Predictions (Volume 4 of 4:
Barnes, J.
Climate Change Indicator Results) (Report No: 07/2009)
King, J., Brown, C.A.
Okavango River Basin Environmental Flow Assessment Project
and Barnes, J.
Final Report (Report No: 08/2009)
Malzbender, D.
Environmental Protection And Sustainable Management Of The
Okavango River Basin (EPSMO): Governance Review
Vanderpost, C. and
Database and GIS design for an expanded Okavango Basin
Dhliwayo, M.
Information System (OBIS)
Veríssimo, Luis
GIS Database for the Environment Protection and Sustainable
Management of the Okavango River Basin Project
Wolski,
P.
Assessment of hydrological effects of climate change in the
Okavango Basin
Country Reports
Angola
Andrade e Sousa,
Análise Diagnóstica Transfronteiriça da Bacia do Rio
Biophysical Series
Helder André de
Okavango: Módulo do Caudal Ambiental: Relatório do
Especialista: País: Angola: Disciplina: Sedimentologia &
52
EFA Botswana Birds
Geomorfologia
Gomes, Amândio
Análise Diagnóstica Transfronteiriça da Bacia do Rio
Okavango: Módulo do Caudal Ambiental: Relatório do
Especialista: País: Angola: Disciplina: Vegetação
Gomes,
Amândio
Análise Técnica, Biofísica e Socio-Económica do Lado
Angolano da Bacia Hidrográfica do Rio Cubango: Relatório
Final:Vegetação da Parte Angolana da Bacia Hidrográfica Do
Rio Cubango
Livramento, Filomena
Análise Diagnóstica Transfronteiriça da Bacia do Rio
Okavango: Módulo do Caudal Ambiental: Relatório do
Especialista: País: Angola: Disciplina:Macroinvertebrados
Miguel, Gabriel Luís
Análise Técnica, Biofísica E Sócio-Económica do Lado
Angolano da Bacia Hidrográfica do Rio Cubango:
Subsídio Para o Conhecimento Hidrogeológico
Relatório de Hidrogeologia
Morais, Miguel
Análise Diagnóstica Transfronteiriça da Bacia do Análise Rio
Cubango (Okavango): Módulo da Avaliação do Caudal
Ambiental: Relatório do Especialista País: Angola Disciplina:
Ictiofauna
Morais,
Miguel
Análise Técnica, Biófisica e Sócio-Económica do Lado
Angolano da Bacia Hidrográfica do Rio Cubango: Relatório
Final: Peixes e Pesca Fluvial da Bacia do Okavango em Angola
Pereira, Maria João
Qualidade da Água, no Lado Angolano da Bacia Hidrográfica
do Rio Cubango
Santos,
Carmen
Ivelize
Análise Diagnóstica Transfronteiriça da Bacia do Rio
Van-Dúnem S. N.
Okavango: Módulo do Caudal Ambiental: Relatório de
Especialidade: Angola: Vida Selvagem
Santos, Carmen Ivelize
Análise Diagnóstica Transfronteiriça da Bacia do Rio
Van-Dúnem S.N.
Okavango:Módulo Avaliação do Caudal Ambiental: Relatório de
Especialidade: Angola: Aves
Botswana Bonyongo, M.C.
Okavango River Basin Technical Diagnostic Analysis:
Environmental Flow Module: Specialist Report: Country:
Botswana: Discipline: Wildlife
Hancock, P.
Okavango River Basin Technical Diagnostic Analysis:
Environmental Flow Module : Specialist Report: Country:
Botswana: Discipline: Birds
Mosepele,
K. Okavango River Basin Technical Diagnostic Analysis:
Environmental Flow Module: Specialist Report: Country:
Botswana: Discipline: Fish
Mosepele, B. and
Okavango River Basin Technical Diagnostic Analysis:
Dallas, Helen
Environmental Flow Module: Specialist Report: Country:
Botswana: Discipline: Aquatic Macro Invertebrates
Namibia
Collin Christian &
Okavango River Basin: Transboundary Diagnostic Analysis
Associates CC
Project: Environmental Flow Assessment Module:
Geomorphology
Curtis, B.A.
Okavango River Basin Technical Diagnostic Analysis:
Environmental Flow Module: Specialist Report Country:
Namibia Discipline: Vegetation
Bethune, S.
Environmental Protection and Sustainable Management of the
Okavango River Basin (EPSMO): Transboundary Diagnostic
Analysis: Basin Ecosystems Report
Nakanwe, S.N.
Okavango River Basin Technical Diagnostic Analysis:
Environmental Flow Module: Specialist Report: Country:
Namibia: Discipline: Aquatic Macro Invertebrates
Paxton,
M. Okavango River Basin Transboundary Diagnostic Analysis:
Environmental Flow Module: Specialist
Report:Country:Namibia: Discipline: Birds (Avifauna)
Roberts, K.
Okavango River Basin Technical Diagnostic Analysis:
Environmental Flow Module: Specialist Report: Country:
Namibia: Discipline: Wildlife
Waal,
B.V. Okavango River Basin Technical Diagnostic Analysis:
Environmental Flow Module: Specialist Report: Country:
Namibia:Discipline: Fish Life
Country Reports
Angola
Gomes, Joaquim
Análise Técnica dos Aspectos Relacionados com o Potencial
Socioeconomic
Duarte
de Irrigação no Lado Angolano da Bacia Hidrográfica do Rio
Series
Cubango: Relatório Final
Mendelsohn,
.J.
Land use in Kavango: Past, Present and Future
Pereira, Maria João
Análise Diagnóstica Transfronteiriça da Bacia do Rio
Okavango: Módulo do Caudal Ambiental: Relatório do
Especialista: País: Angola: Disciplina: Qualidade da Água
Saraiva, Rute et al.
Diagnóstico Transfronteiriço Bacia do Okavango: Análise
Socioeconómica Angola
53
EFA Botswana Birds
Botswana Chimbari, M. and
Okavango River Basin Trans-Boundary Diagnostic Assessment
Magole, Lapologang
(TDA): Botswana Component: Partial Report: Key Public Health
Issues in the Okavango Basin, Botswana
Magole,
Lapologang
Transboundary Diagnostic Analysis of the Botswana Portion of
the Okavango River Basin: Land Use Planning
Magole, Lapologang
Transboundary Diagnostic Analysis (TDA) of the Botswana p
Portion of the Okavango River Basin: Stakeholder Involvement
in the ODMP and its Relevance to the TDA Process
Masamba,
W.R.
Transboundary Diagnostic Analysis of the Botswana Portion of
the Okavango River Basin: Output 4: Water Supply and
Sanitation
Masamba,W.R.
Transboundary Diagnostic Analysis of the Botswana Portion of
the Okavango River Basin: Irrigation Development
Mbaiwa.J.E. Transboundary Diagnostic Analysis of the Okavango River
Basin: the Status of Tourism Development in the Okavango
Delta: Botswana
Mbaiwa.J.E. &
Assessing the Impact of Climate Change on Tourism Activities
Mmopelwa, G.
and their Economic Benefits in the Okavango Delta
Mmopelwa,
G.
Okavango River Basin Trans-boundary Diagnostic Assessment:
Botswana Component: Output 5: Socio-Economic Profile
Ngwenya, B.N.
Final Report: A Socio-Economic Profile of River Resources and
HIV and AIDS in the Okavango Basin: Botswana
Vanderpost,
C.
Assessment of Existing Social Services and Projected Growth
in the Context of the Transboundary Diagnostic Analysis of the
Botswana Portion of the Okavango River Basin
Namibia
Barnes, J and
Okavango River Basin Technical Diagnostic Analysis:
Wamunyima, D
Environmental Flow Module: Specialist Report:
Country: Namibia: Discipline: Socio-economics
Collin Christian &
Technical Report on Hydro-electric Power Development in the
Associates CC
Namibian Section of the Okavango River Basin
Liebenberg, J.P.
Technical Report on Irrigation Development in the Namibia
Section of the Okavango River Basin
Ortmann, Cynthia L.
Okavango River Basin Technical Diagnostic Analysis:
Environmental Flow Module : Specialist Report Country:
Namibia: discipline: Water Quality
Nashipili,
Okavango River Basin Technical Diagnostic Analysis: Specialist
Ndinomwaameni
Report: Country: Namibia: Discipline: Water Supply and
Sanitation
Paxton,
C.
Transboundary Diagnostic Analysis: Specialist Report:
Discipline: Water Quality Requirements For Human Health in
the Okavango River Basin: Country: Namibia
54
EFA Botswana Birds
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