Uganda's only alkaline lakes are found in the Queen Elizabeth Conservation Area and the adjoining Kyambura Wildlife Reserve. Both are Important Bird Areas, a status to which the birds of the lakes contribute. A total of 179 waterbird counts were made between 1984 and 2000, covering eight of the nine alkaline lakes, all of which are small explosion craters. Of the 75 species counted, all but three were non-specialists. Maxima are given for all species, together with seasonal data for five crater lakes. Four lakes regularly supported more than 1,000 Lesser Flamingos each, the maximum being 60,000. They were Maseche, Bagusa, Nshenyi and Munyanyange. Breeding has been attempted, but has been unsuccessful so far. The more important flamingo lakes had high values for conductivity, above 15,000 μS cm−2, whilst species richness is associated with muddy shores and, probably, intermediate levels of alkalinity, between 10 and 50 Meq−1. The lakes are important scenically, for ecotourism, and for the conservation of waterbirds and plants; whilst Lake Katwe's traditional production of salt is of considerable economic significance.
WATERBIRDS OF ALKALINE LAKES IN WESTERN UGANDADerek PomeroyMakerere University Institute of Environment and Natural ResourcesP.O. Box 7298, Kampala, Ugandaderek@imul.comAchilles ByaruhangaNature UgandaP.O. Box 27034, Kampala, Ugandaachilles.firstname.lastname@example.orgMalcolm Wilson32 'Second Avenue' 2⟨sup⟩nd⟨/sup⟩ road, Hyde Park 2196Johannesburg, South AfricaShoebill@mweb.co.zaABSTRACTUganda's only alkaline lakes are found in the Queen Elizabeth Conservation Area and the adjoining Kyambura Wildlife Reserve. Both are Important Bird Areas, a status to which the birds of the lakes contribute. A total of 179 waterbird counts were made between 1984 and 2000, covering eight of the nine alkaline lakes, all of which are small explosion craters. Of the 75 species counted, all but three were non-specialists. Maxima are given for all species, together with seasonal data for five crater lakes. Four lakes regularly supported more than 1,000 Lesser Flamingos each, the maximum being 60,000. They were Maseche, Bagusa, Nshenyi and Munyanyange. Breeding has been attempted, but has been unsuccessful so far. The more important flamingo lakes had high values for conductivity, above 15,000 µS cm⟨sup⟩-2⟨/sup⟩, whilst species richness is associated with muddy shores and, probably, intermediate levels of alkalinity, between 10 and 50 Meq⟨sup⟩-1⟨/sup⟩. The lakes are important scenically, for ecotourism, and for the conservation of waterbirds and plants; whilst Lake Katwe's traditional production of salt is of considerable economic significance.INTRODUCTIONThe western rift valley in Uganda, also known as the Albertine Rift, contains over a hundred explosion craters. They originated during the development of the Rift, probably only a few thousand years ago (H. Osmaston, pers. comm.). Some 50 of the craters lie within the Queen Elizabeth Conservation Area (QECA), which includes the QE National Park, Kyambura Wildlife Reserve (KWR) and the Kazinga Animal Sanctuary. Together, these comprise two of Uganda's Important Bird Areas (Byaruhanga et al., 2001). Eighteen of the craters contain lakes, and of those nine are alkaline. Regular counts have been made of the waterbirds on these alkaline lakes, which support a higher diversity of species compared to the freshwater lakes. Several of the lakes lie within the Maramagambo Forest. This study includes all the alkaline lakes with high waterbird numbers and species richness, and one freshwater lake (figure 1). In this paper, we document the waterbirds as well as indicate the conservation importance of Uganda's only alkaline lakes.Figure 1. Part of the Queen Elizabeth Conservation Area (29°50'-30°12' E, 0°00'-0°10' south), showing the crater lakes included in this study ((F) = Freshwater, the remainder being alkaline). The two parts of the Kazinga Animal Sanctuary are stippled.The alkalinity of some of the lakes is largely associated with sodium and potassium salts, and presence of calcium and magnesium ions. For this reason, we prefer the term alkaline to saline. For hundreds of years, people have been extracting salt from Lake Katwe, which has sufficiently high concentrations of both sodium and chloride ions. In the 19⟨sup⟩th⟨/sup⟩ century, Lake Katwe was on the Arab trade routes because of its salt, as well as ivory. Presently it is the main salt industry in the area with several thousand people working, while a few others work for the only other, but small-scale, salt industry at Lake Kasenyi.Whilst very small compared to the famous lakes in Kenya and Tanzania, in the eastern rift valley such as Bogoria, Natron and Nakuru, the alkaline lakes in western Uganda are of considerable ornithological interest. They are all shallow, with the depths of most being less than a metre. Other major characteristics of the lakes considered in this study are given in table 1.Table 1. Key characteristics of the main crater lakes of the QECA. Except where otherwise indicated, figures for water chemistry are from C. Alokait (pers. comm.); they are averages of 3-4 readings from each lake, except for pH where the full range is given. Lake George is included for comparison.ALKALINE LAKESFRESHWATER LAKESLakes with many flamingos⟨sup⟩a⟨/sup⟩Lakes with few flamingosMasecheBagusaNshenyiMunyanyangeKatweNyamunukaKikorongoKasenyiChibweraGeorgePre 19901998Approx. area (ha)⟨sup⟩c⟨/sup⟩35⟨sup⟩c⟨/sup⟩3550⟨sup⟩c⟨/sup⟩50⟨sup⟩c⟨/sup⟩25090⟨sup⟩c⟨/sup⟩8090408024,000Conductivity (µS/cm)45,000⟨sup⟩d⟨/sup⟩110,000110,00037,000385,000-455,000⟨sup⟩d⟨/sup⟩88,00016,300-34,600⟨sup⟩d⟨/sup⟩9,00080,000⟨sup⟩d⟨/sup⟩600300Alkalinity (meq/l)710⟨sup⟩d⟨/sup⟩---1330-2120⟨sup⟩d⟨/sup⟩-144-498⟨sup⟩d⟨/sup⟩125377⟨sup⟩d⟨/sup⟩110125pH8.6-10.78.7-12.38.5-11.58.9-9.510.0-11.610.5-11.79.4-10.0⟨sup⟩d⟨/sup⟩8.0-10.111.8-12.77.7-9.27.3-9.0Notesa maxima exceeding 1000 (Table 2).b lake areas as shown on 1:50,000 maps represent 'high water marks'c completely dry in some yearsd from Mungoma (1990)MATERIALS AND METHODSWaterbird counts have been carried out regularly at a number of lakes in Uganda since 1984, mainly by DP and MW (but see also the Acknowledgements); and at the KWR lakes since 1994 by a Nature Uganda team led by AB. The counts were done using standard binoculars and telescopes. Most of these lakes are approximately 1 km or less across, but in some, notably Kikorongo and Munyanyange, many counts involved a complete circuit of the lake, on foot. Where time allowed, total counts were made, but not all counts at all lakes were total counts, and hence results are mainly given as maxima rather than averages.Water in all the nine lakes was sampled by Christine Alokait in 1998; some of her data are included in table 1. Standard meters were used to determine the conductivity and pH. Conductivity is a measure (in micro-Siemens per centimetre) of total ionic nutrients in the water, and like pH is readily measured in the field. Alkalinity, which was measured in the laboratory by titration, reflects the amount of bicarbonate present, which in turn is important for algal production. These values are taken from a review by Mungoma (1990) which, however, included only four of the lakes in this study, those for Lake Kikorongo being pre- 1990 values. Periodically Lake George's fresh waters overflow into the nearby Kikorongo. Between floods the water level in Lake Kikorongo drops as a result of evaporation, and it becomes increasingly alkaline. This was the case during the present study. Until 1992, the lake was small due to low water levels. A series of floods from 1993 onwards progressively raised the water level by about 10 metres and consequently diluted it, so that by the year 2000, its composition was approaching that of a freshwater lake (table 1).RESULTS AND DISCUSSIONNumbers and seasonalityTable 2 shows the highest numbers of all species recorded at all lakes. The alkaline lakes fall naturally into three groups according to the numbers of Lesser Flamingos: (1) those that regularly support thousands of Lesser Flamingos, (2) those that have few, and (3) those that have none. Of the 75 species included in the table, 72 are waterbirds (W and w, as described in the footnote to table 2). The remaining few species, such as the Cattle Egrets, are included because of their regular use of the lake areas.Seasonal data for the five most-frequently visited lakes are given, from west to east, in tables 3 to 7 (the KWR lakes are usually only visited for waterbird counts in January and July). Amongst the species that show marked seasonality are the five included in figure 2. At Lake Munyanyange, the peak numbers of most waterbird species, including Lesser Flamingos, occur from October to December when the lake levels are normally high. Flamingo numbers at all lakes vary greatly (see below) and undoubtedly long-distance migration is involved, since the nearest other places with thousands of flamingos are all in the eastern rift valley, more than 600 km away. They are probably mainly influenced by water levels, which indirectly affect their food supply; but sometimes, when the lakes dry up, the effect is direct.The Avocet was only recorded twice in Uganda before 1980 (Carswell et al., in press), but during the 1980s and 1990s it has been frequent at Lake Munyanyange. However, that is the only place in Uganda where it occurs regularly, primarily as a winter visitor, although its status elsewhere in East Africa is not clear (Britton, 1980, Lewis & Pomeroy, 1989, Zimmerman et al., 1996). Lesser Black-backed Gulls and Gull-billed Terns are winter visitors too, whereas the White-winged Black Tern is predominantly a passage migrant with numbers peaking in April-June. These last three species feed extensively on Lakes George and Edward, which are fresh, using Lake Munyanyange (and occasionally other places such as the Kazinga Channel) for roosting. Interestingly, the White-winged Black Tern is most frequent elsewhere in QECA on autumn passage, mainly November-December (MW, pers. obs.).Table 2. Maximum bird numbers recorded from all lakes, 1984-2000. Common and scientific names of birds, and the order of species, are from the Bird Atlas of Uganda (Carswell et al., in press), and are preceded by their atlas numbers.ALKALINE CRATER LAKESFRESH WATER LAKESpecies of conservation concern⟨sup⟩a⟨/sup⟩Water-birds⟨sup⟩b⟨/sup⟩Lakes with many flamingosLakes with few flamingosNo flamingosMasecheBagusaNshenyiMunyanyangeKatweNyamunukaKikorongoKasenyiKitagataMusumuliChibwera1984-921993-992Little Grebe Tachybaptus ruficollisR-RRW330300267310421505Greater Cormorant Phalacrocorax carboW18White Pelican Pelecanus onocrotalusW1400759Pink-backed Pelican P. rufescensW2178001217Cattle Egret Bubulcus ibis16771296552823175P21Little Egret Egretta garzettaW19111118P22Yellow-billed Egret E. intermediaW6423Great White Egret E. albaR-VUW111625Grey Heron Ardea cinereaR-NTW421595126Black-headed Heron A. melanocephalaw1127Goliath Heron A. goliathR-NTW1128Hamerhop Scopus umbrettaw2131268ALKALINE CRATER LAKESFRESH WATER LAKESpecies of conservation concern⟨sup⟩a⟨/sup⟩Water- birds⟨sup⟩b⟨/sup⟩Lakes with many flamingosLakes with few flamingosNo flamingosMasecheBagusaNshenyiMunyanyangeKatweNyamunukaKikorongoKasenyiKitagataMusumuliChibwera29Yellow-billed Stork Mycteria ibisW3221221271230Open-billed Stork Anastomus lamelligerusw314034White Stork Ciconia ciconia135Saddle-billed Stork Ephippiorhynchus senegalensisR-VUW32036Marabou Stork Leptoptilos crumeniferusW3145015773598038Glossy Ibis Plegadis falcinellusW34039Hadada Bostrychia hagedashw113642Sacred Ibis Threskiornis aethiopicaW663621144African Spoonbill Platalea albaW16445Greater Flamingo Phoenicopterus ruberW2246Lesser Flamingo P. minorG-NT, R-RR, R-NTW60,000⟨sup⟩c⟨/sup⟩12- 15,00020,0004000400753112035047Fulvous Whistling Duck Dendrocygna bicolorw1748White-faced Whistling Duck D. viduataw6550Egyptian Goose Alopochen aegyptiacusw1328521551280353Knob-billed Duck Sarkidiornis melanotosW4410157Yellow-billed Duck Anas undulataW560Red-billed Teal A. erythrorhynchaW4961Hottentot Teal A. hottentotaW1362Garganey A. querquedulaW2169Osprey Pandion haliaetusW4276Fish Eagle Haliaeetus vociferW231537293African Marsh Harrier Circus ranivorusR-VUW1294Eurasian Marsh Harrier C. aeruginosasw211178Black Crake Amaurornis flavirostrisW1185Grey Crowned Crane Balearica regulorumR-NTW32186African Finfoot Podica senegalensisR-VUW1197Black-winged Stilt Himantopus himantopusW30001000400060015073260L198Avocet Recurvirostra avosettaW67201Water Thicknee Burhinus vermiculatusw1523637207Common Pratincole Glareola pratincolaw141211Ringed Plover Charadrius hiaticulaw12556212Kittlitz's Plover C. pecuariusw2400653720213Three-banded Plover C. tricollarisw22215Kentish Plover Charadrius alexandrinusw1216White-fronted Sandplover C. marginatusw13219Caspian Plover C. asiaticus93ALKALINE CRATER LAKESFRESH WATER LAKESpecies of conservation concern⟨sup⟩a⟨/sup⟩Water- birds⟨sup⟩b⟨/sup⟩Lakes with many flamingosLakes with few flamingosNo flamingosMasecheBagusaNshenyiMunyanyangeKatweNyamunukaKikorongoKasenyiKitagataMusumuliChibwera220Grey Plover Pluvialis squatarolaW1221Wattled Plover Vanellus senegallusW2225223Spur-winged Plover V. spinosusw536148052274429225Senegal Plover V. lugubrisW18229Little Stint Calidris minutaW3541090501152530231Curlew Sandpiper Calidris ferrugineaW140185234Ruff Philomachus pugnaxW25090080370253310236Common Snipe Gallinago gallinagoW1239Black-tailed Godwit Limosa limosaW71241Whimbrel Numenius phaeopusw6242Curlew N. arquataw2243Spotted Redshank Tringa erythropusw12244Redshank T. totanusw11245Marsh Sandpiper T. stagnatalisw21304246Greenshank T. nebulariaW3166113247Green Sandpiper T. ochropusW1248Wood Sandpiper T. glareolaW241358001250Common Sandpiper Actitis hypoleucosW1362132254Grey-headed Gull Larus cirrocephalusW102255Black-headed Gull L ridibundusW1257Lesser Black-backed Gull Larus fuscusW1555258Herring Gull L heugliniW2259Gull-billed Tern Gelochelidon niloticaW427802040264White-winged Black Tern Chlidonias leucopterusW75030002015002502406200L10265African Skimmer Rynchops flavirostrisG-NT.R- VU.R-RRW2003290Water Thick-knee Psittacus erithacusW1323616383Pied Kingfisher Ceryle rudisW611Number of counts12141358232510915114Number of species21242056916373024506Notes:a - Global (G-) species from BirdLife International (2000); Regional (R-) species from Bennun & Njoroge (1996); VU = vulnerable, NT = Near-threatened, RR =Species of regional responsibilityb - Waterbirds as classified by Wilson (1995); W = Waterbird specialists, w = non-specialist species associated with waterc - 19 July 99 (M.Wilson)P - present L - 'large numbers'Figure 2. Seasonality in maximum numbers of several species, thus: a) Lesser Flamingo at Lake Munyanyange (LM); b) Lesser Flamingo, combined totals of KWR lakes (N = no count); c) Avocet at LM; d) Lesser Black-backed Gull at LM; e) Gull-billed Tern at LM; f) White-winged Black Tern at LM; g) Relative mean water levels at LM, on a 0-5 scale.Table 3. Maximum counts* for Lake Katwe, 1984-1999, arranged seasonally.Jan-MarApr-JuneJuly-SeptOct-Dec17Cattle Egret Bubulcus ibis652021Little Egret Egretta garzetta125Grey Heron Ardea cinerea236Marabou Stork Leptoptilos crumeniferus146Lesser Flamingo Phoeniconaias minor33540031017550Egyptian Goose Alopochen aegyptiacus2201Water Thicknee Burhinus vermiculatus2223Spur-Winged Plover Vanellus spinosus5257Lesser Black-Backed Gull Larus fuscus51120264White-Winged Black Tern Chlidonias leucopterus21Number of counts10274Water levels- fairly high at all times -* No total counts, except for Lesser FlamingoConservation valuesSome of the species recorded are of global conservation importance (BirdLife International, 2000), and others are on the East African Red Data List (Bennun and Njoroge, 1996). Both Lesser Flamingo and African Skimmer are globally-listed as near- threatened, and five additional species are considered to be regionally vulnerable (table 2). Four more species, including the White Pelican, are listed as being of lesser concern, regionally. (There is also an unconfirmed record of 1,800 White Pelicans on Lake Kasenyi (Byaruhanga et al., 2001)). Several of these species have been recorded in significant numbers, with the Lesser Flamingo and White Pelican, together with the non- threatened Black-winged Stilt and Gull-bulled Tern, exceeding the Wetland International's threshold numbers for congregatory species (Dodman et al., 1997). Today, the Kyambura craters are by far the most important site in Uganda for Lesser Flamingos. Because of their attractive, partly-forested setting, these craters also have considerable potential for tourism development. For quite different reasons, Lakes Kasenyi and Munyanyange could also become important tourist sites. Kasenyi is close to the most popular lion-viewing area in the QECA, whilst Munyanyange is only a 15- minute drive from the park headquarters at Mweya. It is a sanctuary, within the park, and can readily be circumnavigated by car or on foot, making bird-watching very easy. Fifty-three waterbird species (W and w) have been recorded from this small lake, indicating a remarkably high level of diversity.Table 4. Maximum counts for Lake Munyanyange, 1984-1999, arranged seasonally.Jan-MarApr-JuneJuly-SeptOct-Dec2Little Grebe Tachybaptus ruficollis4528738White Pelican Pelecanus onocrotalus39Pink-Backed Pelican Pelecanus rufescens117Cattle Egret Bubulcus ibis42577012921Little Egret Egretta garzetta31123Great White Egret Egretta alba425Grey Heron Ardea cinerea141126Black-Headed Heron Ardea melanocephala111128Hamerkop Scopus umbretta129Yellow-Billed Stork Mycteria ibis102134White Stork Ciconia ciconia135Saddle-Billed Stork Ephippiorhynchus senegalensis336Marabou Stork Leptoptilos crumeniferus10219045020038Glossy Ibis Plegadis falcinellus4021139Hadada Bostrychia hagedash2642Sacred Ibis Threskiornis aethiopica121492144African Spoonbill Platalea alba145Greater Flamingo Phoenicopterus ruber4246Lesser Flamingo⟨sup⟩a⟨/sup⟩ Phoeniconaias minor30004902000400050Egyptian Goose Alopochen aegyptiacus332238553Knob-billed Duck Sarkidiornis melanotos24157Yellow-billed Duck Anas undulata560Red-billed Teal Anas erythrorhyncha154961Hottentot Teal Anas hottentota1321262Garganey Anas querquedula2176Fish Eagle Haliaeetus vocifer1193African Marsh Harrier Circus ranivorus2185Grey-Crowned Crane Balearica regulorum3197Black-winged Stilt Himantopus himantopus600250120260198Avocet Recurvirostra avosetta6792020201Water Thicknee Burhinus vermiculatus25211Ringed Plover Charadrius hiaticula51251212Kittlitz's Sandplover Charadrius pecuarius60400304213Three-banded Plover Charadrius tricollaris1219Caspian Plover Charadrius asiaticus9220Grey Plover Pluvialis squatarola1221Wattled Plover Vanellus senegallus1025102223Spur-winged Plover Vanellus spinosus36801263225Senegal Plover Vanellus lugubris18229Little Stint Calidris minuta50020451090231Curlew Sandpiper Calidris ferruginea6514022234Ruff Philomachus pugna10030300370239Black-tailed Godwit Limosa limosa47241Whimbrel Numenius phaeopus6242Curlew Numenius arquata12243Spotted Redshank Tringa erythropus11244Redshank Tringa totanus1245Marsh Sandpiper Tringa stagnatalis25147246Greenshank Tringa nebularia66145247Green Sandpiper Tringa ochropus11248Wood Sandpiper Tringa glareola8004410250Common Sandpiper Actitis hypoleucos12Jan-MarApr-JuneJuly-SeptOct-Dec254Grey-headed Gull Larus cirrocephalus5710255Black-headed Gull Larus ridibundus1257Lesser Black-backed Gull⟨sup⟩b⟨/sup⟩ Larus fuscus1555120447258Herring Gull Larus heuglini2259Gull-billed Tern Gelochelidon nilotica650150780264White-winged Black Tern⟨sup⟩c⟨/sup⟩ Chlidonias leucopterus50015002530Number of counts⟨sup⟩d⟨/sup⟩19121115Average water level⟨sup⟩e⟨/sup⟩2.13.01.63.9NOTESa most pre-1990 maxima were ⟨1000bonly singles to 1987cmainly pre-1988dnot all were 'complete'efrom 0 = dry to 5 = full; the lake could be full at any time, in different years, but most frequently between October and MarchTable 5. Maximum counts⟨sup⟩a⟨/sup⟩ for Lake Nyamunuka, 1985-1999, arranged seasonally.Jan-MarApr-JuneJuly-SeptOct-Dec17Cattle Egret Bubulcus ibis525Grey Heron Ardea cinerea129Yellow-billed Stork Mycteria ibis236Marabou Stork Leptoptilos crumeniferus457146Lesser Flamingo Phoeniconaias minor4565757050Egyptian Goose Alopochen aegyptiacus15253Knob-billed Duck Sarkidiornis melanotos294Eurasian Marsh Harrier Circus aeruginosus1197Black-winged Stilt Himantopus himantopus1505030211Ringed Plover Charadrius hiaticula54223Spur-Winged Plover Vanellus spinosus1229Little Stint Calidris minuta5015234Ruff Philomachus pugnax2025246Greenshank Tringa nebularia1250Common Sandpiper Actitis hypoleucos51264White-Winged Black Tern Chlidonias leucopterus505050Number of counts11474Average water level⟨sup⟩b⟨/sup⟩2.94.03.04.7⟨sup⟩a⟨/sup⟩ No total counts, except Lesser Flamingo⟨sup⟩b⟨/sup⟩ Scored as in Table 4The alkaline lakes have other conservation values. These include salt licks for large mammals, and a number of rare salt-tolerant plants that occur around the edges of the lakes (A.B. Katende, pers. comm.).Species richness (the total numbers of species) was higher in lakes with intermediate alkalinity (table 1) and especially on those that are shallow with large areas of exposed mud. Lake Munyanyange is so shallow that the larger species can often be seen wading hundreds of metres from the shore.The congregations of Gull-billed Terns at Lake Munyanyange, Great White Pelicans at Kasenyi, and Lesser Flamingos in the KWR, all meet the criteria for Important Bird Areas. Clearly these crater lakes, like those to the south of Fort Portal (Pomeroy and Seavy, 2003), are of value for conservation, as well as for their physical attractions as landscape features, and economically for the salt.Table 6. Maximum counts for Lake Kikorongo, 1984-1999, arranged seasonally. The lake was brackish prior to 1993, when floods from Lake George diluted the water. The two data sets are therefore shown separately.1984-19921993-2000Jan-MarApr-JuneJuly-SeptOct-DecJan-MarApril-JuneJuly-SeptOct-Dec2Little Grebe Tachybaptus ruficollis8104414428White Pelican Pelecanus onocrotalus1414009Pink-Backed Pelican Pelecanus rufescens71780017Cattle Egret Bubulcus ibis202813323121Little Egret Egretta garzetta1113823Great White Egret Egretta alba21625Grey Heron Ardea cinerea5911812415126Black-headed Heron Ardea melanocephala127Goliath Heron Ardea goliath128Hamerkop Scopus umbretta113129Yellow-Billed Stork Mycteria ibis1222911272330Open-billed Stork Anastomus lamelligerus3235Saddle-billed Stork Ephippiorhynchus senegalensis122036Marabou Stork Leptoptilos crumeniferus732359542Sacred Ibis Threskiornis aethiopica144African Spoonbill Platalea alba614245Greater Flamingo Phoenicopterus ruber246Lesser Flamingo Phoeniconaias minor311010712048White-faced Whistling Duck Dendrocygna viduata12350Egyptian Goose Alopochen aegyptiacus4051322322728053Knob-billed Duck Sarkidiornis melanotos169Osprey Pandion haliaetus412176Fish Eagle Haliaeetus vocifer2523794Eurasian Marsh Harrier Circus aeruginosus1185Grey-Crowned Crane Balearica regulorum22197Black-winged Stilt Himantopus himantopu4732201Water Thicknee Burhinus vermiculatis361614207Common Pratincole Glareola pratincola14211Ringed Plover Charadrius hiaticula64212Kittlitz's Sandplover Charadrius pecuarius6545371237213Three-banded Plover Charadrius tricollaris2215Kentish Plover Charadrius alexandrinus1223Spur-winged Plover Vanellus spinosus222713944229Little Stint Calidris minuta1151925231Curlew Sandpiper Calidris ferruginea18539234Ruff Philomachus pugna332239Black-tailed Godwit Limosa limosa1242Curlew Numenius arquata2243Spotted Redshank Tringa erythropus1245Marsh Sandpiper Tringa stagnatalis44246Greenshank Tringa nebularia713250Common Sandpiper Actitis hypoleucos333251Turnstone Arenaria interpres2254Grey-headed Gull Larus cirrocephalus2259Gull-billed Tern Gelochelidon nilotica20264White-winged Black Tern Chlidonias leucopterus24040276265African Skimmer Rynchops flavirostris2005043383Pied Kingfisher Ceryle rudis6121Number of counts4132322(2)Table 7. Maximum counts* for Lake Kasenyi, 1984-2000, arranged seasonally.Jan-MarApr-JuneJuly-SeptOct-Dec8White Pelican Pelecanus onocrotalus75709Pink-backed Pelican Pelecanus rufescens1217Cattle Egret Bubulcus ibis27528Hamerkop Scopus umbretta229Yellow-billed Stork Mycteria ibis312130Open-billed Stork Anastomus lamelligerus2140196036Marabou Stork Leptoptilos crumeniferus518046Lesser Flamingo Phoeniconaias minor2003501706550Egyptian Goose Alopochen aegyptiacus3197Black-winged Stilt Himantopus himantopus412601201Water Thicknee Burhinus vermiculatus82237207Common Pratincole Glareola pratincola1212Kittlitz's Sandplover Charadrius pecuarius2207213Three-banded Plover Charadrius tricollaris12223Spur-winged Plover Vanellus spinosus61629229Little Stint Calidris minuta6305234Ruff Philomachus pugnax10248Wood Sandpiper Tringa glareola1250Common Sandpiper Actitis hypoleucos21259Gull-billed Tern Gelochelidon nilotica40264White-winged Black Tern Chlidonias leucopterus602003383Pied Kingfisher Ceryle rudis1Number of counts1545Average water level**2.03.03.03.7* No total counts, except pelicans and Lesser Flamingo** Scored as in Table 4Lesser FlamingosThere are interesting historical records of Lesser Flamingos at the QECA dating back to 1906 when attempted breeding was first recorded by Pitman (1942). In the 1930s, up to 40,000 Lesser Flamingos attempted to breed, mainly on Lake Kikorongo, but only a few were reported in the 1950s (Din & Eltringham, 1976). These birds were no longer found on Lake Kikorongo after it was diluted by heavy rains and flooding from Lake George in the early 1960s. However in 1968-1970 small numbers were seen on Lake Bagusa (Din & Eltringham, 1970). During that time the Lesser Flamingo was only an occasional visitor, in small numbers, to the QECA. A series of aerial counts over Lake Bagusa gave a peak of 1,121 in April 1969: then in 1974, 20,000 were found in a complete survey of the QECA (Din & Eltringham, 1976). During the 1990s, Lesser Flamingo numbers on Lake Bagusa ranged from 69 to 60,000 (Nature Uganda, unpublished), reflecting a general increase in the QECA.Din & Eltringham (1976) pointed out that the major influxes of Lesser Flamingos in the QE area had been in every third decade: the 1900s, 1930s and 1960s, prompting them to comment ' before a further massive visitation by flamingos in the 1990s is forecast '. Remarkably, the numbers in the 1990s were as high as had ever been reported previously! And of the four decades with high flamingo numbers, breeding was attempted in all but the 1930s: recorded months with nests or eggs are from December to February. So far, however, no breeding attempt has been successful.Alkaline lakes are expected to have a high biomass of algae and flamingos are more-or- less confined to a diet of algae (table 2). The algae are equally numerous on lakes with a conductivity value of only 37,000 µS cm⟨sup⟩-2⟨/sup⟩ as on those where the conductivity is much higher (figure 3). For comparison, values of conductivity on Lake Nakuru, where flamingo numbers can exceed a million, are lower-ranging from 14,000 to 26,000 µS cm⟨sup⟩-2⟨/sup⟩ (Vareschi, 1978). Under these conditions the alga Spirulina platensis, a major food source of the Lesser Flamingo, flourishes.Figure 3. The range of conductivity values for lakes with many flamingos (solid line) is similar to that for lakes with few flamingos (dashed line). But they are absent from the freshwater lakes. The lakes are indicated by their initial letters: Bagusa, Chibwera, Katwe, Kikorongo, Kasenyi (Ks), Maseche, Munyanyange, Nshenyi and Nyamunuka. The two elipses enclose lakes with many and few flamingos: the solid line being the former.Species richness (the total numbers of species) was higher in lakes with intermediate alkalinity (tables 1 and 2) and especially on those that are shallow with large areas of exposed mud. Lake Munyanyange is so shallow that the larger species can often be seen wading hundreds of metres from the shore.The congregations of Gull-billed Terns at Lake Munyanyange, Great White Pelicans at Kasenyi, and Lesser Flamingos in the KWR, all meet the criteria for Important Bird Areas. Clearly these crater lakes, like those to the south of Fort Portal (Pomeroy and Seavy, in prep.), are of value for conservation, as well as for their physical attractions as landscape features, and economically for the salt.ACKNOWLEDGEMENTSMany people took part in the waterbird counts, particularly those undertaken by Nature Uganda, who also thank the Royal Society for the Protection of Birds (UK) and the Global Environment Facility (through UNDP) for financial support. We are grateful for the data on water chemistry, which come from an unpublished study by Christine Alokait, assisted by Yusuf Kizito; this work was supported by the Grant Management Unit of USAID. We also thank the Uganda Wildlife Authority and the people of Katwe and Kasenyi for tolerating our field activities. Lincoln Fishpool and Eleizer Kateyo kindly commented on the manuscript, much of which was prepared by Betty Lutaaya, assisted by Polycarp Mwima for the figures.REFERENCESBennun, L. & P. Njoroge (eds) (1996). Birds to watch in East Africa: a preliminary Red Data list. Research reports of the Centre for Biodiversity, National Museums of Kenya: Ornithology, 23: 1-16. Nairobi.BirdLife International (2000). Threatened birds of the world. Lynx Edicions, Barcelona, Spain.Britton, P.L. (ed.) (1980). Birds of East Africa. East Africa Natural History Society, Nairobi.Byaruhanga, A., P. Kasoma & D. Pomeroy (2001). Important Bird Areas in Uganda. Nature Uganda, Kampala.Carswell, M., D. Pomeroy, J. Reynolds, & H. Tushabe (in press). The bird atlas of Uganda. British Ornithologists' Club, London.Din, N.A. & S.K. Eltringham (1970). The Lesser Flamingo in western Uganda. East African Wildlife Journal 8: 201.Din, N.A. & S.K. Eltringham (1976). Early records of the lesser flamingo Phoeniconaias minor in western Uganda with a note on its present status. East African Wildlife Journal 14: 171-175.Dodman, T., C. de Vaan, E. Hubert & C. Nivet (1997). African Waterfowl Census 1997. Les Dénombrements Internationaux d'oiseaux d'eau en Afrique, 1997. Wetlands International, Wageningen.Government of Uganda (1967). Atlas of Uganda, 2⟨sup⟩nd⟨/sup⟩ edition. Department of Lands and Surveys, Entebbe.Lewis, A. & D. Pomeroy (1989). A Bird Atlas of Kenya. A.A. Balkema, Rotterdam.Marxmeier U, & H. Duttmann (2002). Reed die-back affects breeding biology of the Great Crested Grebe (Podiceps cristatus) at Lake Dummer (Lower Saxony, Germany). Journal Fur Ornithologie 143 (1): 15-32.Mungoma, S. (1990). Alkaline, saline lakes of Uganda: a review. Hydrobiologia 208: 75-80.Pitman, C.R.S. (1942). A game warden takes stock. Nisbet, London.Pomeroy, D. & N. Seavy (2003). Surveys of Great Crested Grebes Podiceps cristatus and other waterbirds on the Kasenda cluster of crater lakes in wetsern Uganda. Journal of East Africa Natural History 92:49-62.Vareschi, E. (1978). The ecology of Lake Nakuru (Kenya). I. Abundance and feeding of the Lesser Flamingo. Oecologica (Berlin) 32: 11-35.Wilson, S.E. (1995). Bird and Mammal Checklists for Ten National Parks in Uganda. National Parks, Kampala.Zimmerman, D.A., D.A. Turner & D.J. Pearson (1996). Birds of Kenya and Northern Tanzania. Princeton Univ. Press, Princeton, New Jersey.