Mycobacterium avium-related epizootic in free-ranging lesser flamingos in Kenya

An epizootic in free-ranging lesser flamingos (Phoeniconaias minor) in Kenya resulted in more than 18,500 deaths from August through mid-November 1993. Disease was concentrated along the shores of Rift Valley Lakes Bogoria and Nakuru (Kenya) and did not involve any of the other avian or mammalian species frequenting the lakes. Coincidental to the outbreak was a bloom of algae on Lake Bogoria, toxins from which were first suspected to be causative. Discrete necrotic and granulomatous lesions were often noted in spleen and liver, and Mycobacterium avium serovar I was isolated from both organs. Escherichia coli and Pseudomonas aeruginosa also were often recovered in pure culture from liver. Gross and histopathological evaluation of the cases disclosed signs of acute sepsis and also chronic, potentially life-threatening lesions of mycobacteriosis, primarily involving the spleen and liver. Lesions typical for algae toxicosis were not seen in any birds. Deaths were attributed to septicemia complicated in those affected, by mycobacteriosis.     

Trends in waterbird numbers in the southern Rift Valley of Kenya

Bennun, L. & Nasirwa, O. 2000. Trends in waterbird numbers in the southern Rift Valley of Kenya. Ostrich 71 (1 & 2): 220–226.

Each January since 1991, volunteer teams have counted waterbirds at major wetlands in the southern Kenyan Rift Valley. There has been consistent coverage at Lakes Naivasha, Elmenteita, Nakuru and (since 1992) Bogoria. These lakes are shallow and, except for Bogoria, fluctuate greatly in extent; all but Naivasha are saline. Lake levels were moderately high in 1991–1993 but have been generally low since. Flamingo totals for the three saline lakes combined were more than one million from 1992–1994, but roughly halved each year since then. Greater Flamingos Phoenicopterus ruber made up between 0.7 and 4.1% of total flamingo numbers; other waterbirds made up between 2.7 and 10.2% of the overall total. Lakes Naivasha, Elmenteita and Nakuru together hold most of the non-flamingo waterbirds in the southern Rift; to compare trends for other species, we pooled totals for these sites. Significant, or near-significant, declines were evident for grebes, pelicans, cormorants, storks, gulls, rallids, kingfishers, terns and raptors. No group showed an overall increasing trend. At Dandora, a smaller site with stable water levels, these groups showed large annual fluctuations but no obvious declines. In most waterbird groups where numbers decreased, the probable cause was sustained low lake levels at Lake Nakuru; numbers at Lake Naivasha remained stable. Exceptions were rallids, kingfishers and raptors, where numbers steadily declined at Naivasha. There is a need to investigate local environmental causes of these changes for kingfishers and raptors, and to assess possible loss of breeding sites for rallids.     

The flamingo and pelican populations of the Rift Valley Lakes in 1968-69

Aerial photographic sample censuses of the flamingoes and pelicans on Lakes Nakuru and Hannington were carried out on four occasions between October 1968 and March 1969. On Lake Nakuru the estimated numbers of flamingoes varied between 172 000 and 401 000, and the pelicans between 6800 and 27 900. There were no pelicans on Lake Hannington, but the number of flamingoes varied between 507 000 and 634 000. It was not possible to distinguish between greater and lesser flamingoes, or between white and pink-backed pelicans on the aerial photographs. On 28–30 March 1969 a census was carried out on twenty-four lakes, between Lake Hannington in the north and the Singida lakes in the south. The total number of flamingoes seen was just over one million, with 22 000 pelicans. About 100 000 lesser flamingo nests were counted from aerial photographs taken over Lake Natron in November 1969.     

Patterns of variation in waterbird numbers on four Rift Valley lakes in Kenya, 1991–1999

Waterbird populations were censused each January from 1991 to 1999 at Lakes Naivasha, Elmenteita and Nakuru and from 1992 at Lake Bogoria. These shallow lakes in the Kenyan Rift Valley fluctuate greatly in water level and alkalinity. All but Naivasha are usually saline; Nakuru and Elmenteita at times support fish, while Bogoria is fishless. A standardized logarithmic index of relative abundance (value 1.0 for the mean) was calculated for each major waterbird group at each lake, and for Naivasha, Elmenteita and Nakuru combined (combined lakes). Its variance was used to compare levels of variation within and across lakes. For the combined lakes, there was high variance in large piscivores (whether combined or separated into groups), grebes, rallids and flamingos. There was low variance in Palaearctic waders (combined or separated into groups), ibises and spoonbills and birds of prey. However, the lakes generally showed idiosyncratic patterns of variation across the different groups. Variance in the indices for birds of prey and kingfishers were consistently low (max. 0.036 and 0.042, respectively), but no group had consistently high variance across all sites. The variance for all birds (other than flamingos) combined was low (0.018 – 0.085) and similar across all lakes and for combined lakes (0.018). For the combined lakes, the variance for flamingos was five times higher than for all other birds (p<0.05), though the two variances were almost equal for Bogoria. Flamingos were the most variable at Naivasha (variance 0.281) followed by Elmenteita (0.177), Nakuru (0.101) and Bogoria (0.024, and significantly lower than all the rest, p<0.05). This was opposite in order to the mean numbers of flamingos recorded at each site. Large piscivores were relatively stable at Naivasha (variance 0.005) but much more variable at Elmenteita (0.199) and Nakuru (0.269). Patterns of variation within lakes were correlated for some groups, such as waders at Naivasha and large piscivores at Nakuru. These correlations could be related to local ecological conditions. However, there were few large correlations across sites, and these were mainly direct. There was, therefore, no evidence that a fixed population of waterbirds was distributing itself across sites according to conditions. Each lake thus seems to represent and independent entity, while the waterbirds they host evidently move much more widely afield than this portion of the Rift Valley.     

AN ECOLOGICAL SURVEY OF THE BIRDS OF THE CRATER HIGHLANDS AND RIFT LAKES, NORTHERN TANGANYIKA TERRITORY.

Bird-plant communities are described. Moorland: effect of incomplete forest barrier in extending population as compared with Kilimanjaro. Upland grasslands: four subdivisions with distinctive avifauna tabularly compared. Upland bushland: two subdivisions. Evergreen forest. Upland waters. Intermediate scattered-tree grasslands: lodgment of distinctive populations. Ground-water forest. Lake and swamp: comparison between populations of Lakes Natron, Manyara and Embagai; analysis of migrant movements and biotic preferences among waterfowl.
Breeding seasons: contrast between upper and lower zones, in some cases implying biological races of common species.
Evolutionary significance of population; probable recent development of the four or five endemics; very mixed affinities of the remainder, which include forms associated with Kilimanjaro, Chyulu, Kenya Highlands, Lake Victoria basin, Uganda and S.W. Tanganyika, considered to indicate rather recent colonization, but in some instances survival from an earlier epoch.
Systematic notes on 23 species of special interest, including a review of the East African races of Colius striatus , field-notes on newly described races of Pinarochroa sordida and Cisticola hunteri , and a first account of the nesting of Nectarinia johnstoni.     

Satellite tracking Lesser Flamingo movements in the Rift Valley,East Africa: pilot study report

The Lesser Flamingo (Phoeniconaias minor) is thought to be highly nomadic. In East Africa, the number of individuals on a given lake has been shown to double or halve in a period of just two weeks. In general, interlake movements are believed to take place mostly at night. However, movement timing and patterns for individual birds are unknown. Between 12 and 23 October 2002, we affixed two solar-powered and two battery-powered satellite transmitters (PTTs) to four large (>2kg) adult male Lesser Flamingos at Lake Bogoria, Kenya. During the first three months, the four birds exhibited markedly different movement patterns. One moved 687km, making seven visits to four different lakes (mean stay: 11.4d). Another made five visits to only three different lakes (mean stay: 18.5 days), travelling only 263km. On two occasions, it remained on one lake for long periods (34 days and 70 days). A third moved among lakes in Kenya and Tanzania 44 times, visiting nine different lakes, spending an average of only 2.3 days at each and travelling a total of 4 792km in the process. The fourth is believed to have been predated on Lake Bogoria at the end of the first month. During the last six months of the study, the most active bird settled down and the behaviour of the three remaining birds was much more similar. They each spent long periods of time (e.g. 45-137d) at just one or two sites. During the study period, one bird made several short (21-81km) interlake flights during daylight hours. Flight speed was estimated to be approximately 68km h-1 during the only flight when speed could be calculated. Both solar-powered PTTs functioned well; light reaching the solar panels was not impaired by feathers or dried mineral crystals, both initial concerns. The solar-powered PTT with a pre-set 'on/off' duty cycle performed much better than the other with no pre-set duty cycle, indicating that small solar-powered units need substantial 'off' time to recharge their batteries, even in areas with 12h of sunlight daily. The key site network for Lesser Flamingos in East Africa consists of seven alkaline lakes in Kenya and Tanzania (Logipi, Bogoria, Nakuru, Elmenteita, Natron, Manyara and Eyasi) and an ephemeral fresh water wetland in central Tanzania (Bahi Swamp). The conservation status of these eight sites varies from well-protected (lakes Bogoria, Nakuru and Manyara) to completely unprotected (Logipi, Natron, Eyasi and Bahi Swamp), with Elmenteita being partially protected.     

Cyanobacteria blooms—A possible cause of mass mortality of Lesser Flamingos in Lake Manyara and Lake Big Momela, Tanzania

Limnological studies were conducted in three alkaline lakes (Lake Big Momela, Manyara and Embagai) with the aim of investigating the cause of mass mortality of the Lesser Flamingos in Lake Manyara and Lake Big Momela during July–August 2004. High concentrations, up to 150 million filaments per liter of the potentially toxic planktonic cyanobacterium Arthrospira fusiformis were found in surface scum of Lake Big Momela where Lesser Flamingos were dying at a rate of between 15 and 50 individuals per day during the study period. Gut content analyses indicated that A. fusiformis was the main food item in moribund flamingos. Mouse bioassay suggested that the crude microalgal extract dominated by A. fusiformis was toxic with all mice close to death becoming lethargic, with loss of balance, uncoordinated movements, intermittent tremors, dyspnoea with gasping followed by respiratory arrest. This observation gives circumstantial evidence that A. fusiformis at such high concentrations was toxic to the Lesser Flamingo in Lake Big Momela.     

Genetic and morphological analyses indicate high population mixing in the endangered cichlid Alcolapia flock of East Africa

Alcolapia is a minor genus of small-bodied, polymorphic cichlids inhabiting the lagoons and hot springs surrounding the soda lakes Natron (largely in Tanzania) and Magadi (Kenya). Three Alcolapia species are present at Natron (Alcolapia alcalicus, Alcolapia ndalalani and Alcolapia latilabris) and one at Magadi (Alcolapia grahami). All are IUCN Red Listed as either vulnerable or endangered. We performed analyses of morphometric and genetic structure on 13 populations of the Natron Alcolapia flock, and one A. grahami population of Lake Magadi as an out-group. Morphometric analyses revealed significant differentiation in the head and mouth shape of the species at Natron. From a genetic perspective, among 70 mtDNA control region sequences 17 haplotypes were found, showing in the minimum spanning network a star-like pattern around the widespread haplotype 2lat. At Natron, there was limited genetic differentiation between the different populations of A. alcalicus and A. latilabris, despite apparent ecological barriers of extreme alkalinity that suggested their populations were isolated. Instead, there appeared to be some population connectivity, with a rate of 0.5–2.3 migrants per generation suggesting that natural factors, such as intense rains or transmission by large piscivorous birds, facilitate population connectivity and maintain genetic similarity. The outputs of high population connectivity and one genetic unit at the basin level (despite morphological divergence) suggest that any human activities that disrupt the connectivity of the freshwater resources of the Natron catchment could further threaten the integrity and current status of these already threatened fish populations.     

Succession of planktonic rotifer populations in some lakes of the Eastern Rift Valley,Kenya

The quantitative succession of the spring and summer rotifer plankton and its biomass in six lakes of the Eastern Rift Valley of Kenya is discussed. The lakes can be divided into two groups: the low conductivity slightly alkaline lakes Naivasha, Oloidien and the Winam Gulf of Lake Victoria; and the high conductivity, highly alkaline-saline lakes Nakuru, Elmenteita and Bogoria. The former three show a qualitatively rich, typical warmwater rotifer association dominated by Brachionids and Filinia. The saline soda lakes are dominated by several populations of Brachionus dimidiatus, which can reach enormous numbers. The taxonomy and biometry of this species was subjected to statistical analysis. Some interesting and rare species are described: Anuraeopsis coelata, Lepadella triptera f. deconincki, Trichocerca gracilis and T. mus.The chemical limnology of the lakes is discussed and compared with other soda lakes in Central Africa, Europe and North America.     

Cladogenesis and endemism in Tanzanian mole‐rats,genus Fukomys: (Rodentia Bathyergidae): a role for tectonics?

African mole‐rats of the family Bathyergidae are subterranean hystricomorph rodents found throughout sub‐Saharan Africa, where the distributional ranges of the most speciose taxa are divided by the African Rift Valley. In particular, mole‐rats of the genera Heliophobius and Fukomys are distributed widely, and their adaptive radiation appears to have been strongly influenced by the geological process of rifting. As a result, virtually all members of the genus Fukomys occur in locations west of the Rift Valley. However, a small number of isolated populations occur east of the Rift Valley in Tanzania, where Heliophobius is widespread and is the predominant bathyergid rodent. Phylogenetic analysis of mitochondrial cytochrome b sequences of previously unstudied Tanzanian mole‐rats (genus Fukomys) and geographically adjacent populations strongly suggests that vicariance in the Western Rift Valley has subdivided populations of mole‐rats and, together with climatic changes, played a role in the isolation of extralimital populations of Fukomys in Tanzania. Together with molecular clock‐based estimates of divergence times, these results offer strong support for the hypothesis that the observed patterns of cladogenesis are consistent with tectonic activity in the ‘Mbeya triple junction’ and Rungwe volcanic province between Lakes Rukwa and Nyasa. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100 , 337–352.     

THE BREEDING BEHAVIOUR OF THE LESSER FLAMINGO PHOENICONAIAS MINOR

This paper summarizes what has been learned about the breeding behaviour of the Lesser Flamingo Phoeniconaias minor from 1954 to 1969, especially at Lake Magadi, Kenya, in 1962. The only known regular breeding site is on soda mudflats at Lake Natron, Tanzania. Lake Magadi, used in 1962 when Lake Natron was full of water, may only have been used once this century. Breeding has been sporadically reported from other lakes, but reports are usually inadequate and in many cases successful breeding was not proven. At Lake Natron the breeding site is in the middle of the lake which is 70 km long by 24 km wide. Breeding conditions are extremely harsh, mid-day temperatures regularly exceeding 50^oC and reaching 70–75^oC. The advantage of the site lies in its complete freedom from predatory mammals. Details of known breeding, obtained by aerial surveys, are given. Lesser Flamingos do not breed annually, and tend to start in the last quarter, October to December, of any year in which they breed. There is no obvious relation between food supply and this breeding date. The last quarter of the year at Lake Natron tends to be rainy and warm. No really large-scale breeding has been observed since 1962. The methods used for estimating adults and young are given. They have shown good correlation with ground counts at Lake Magadi in 1962. The total population is of the order of three to four million, and the largest known breeding colonies were of 1,100,000 pairs at Lake Magadi in 1962 and 570,000 pairs in 1957 at Lake Natron. From 1953 to 1962 inclusive about 275,000 pairs (1/5 to 1 /6 of the population) bred annually on average, but since 1962 the average number breeding per year has been less, reducing the overall average to perhaps 180,000 pairs. At this rate a pair takes 22–24 years to replace itself. The nuptial display of the Lesser Flamingo resembles in many respects that of the Greater Flamingo Phoenicopterus ruber. When displaying, Lesser Flamingos congregate in a tightly-packed flock, rapidly moving, in which various ritual movements are performed. Display normally takes place in certain sites far from known breeding grounds, and may be stimulated by conditions of very dense population. Lesser Flamingos build mud-mound nests similar to but smaller than those of the Greater Flamingo. Measurements, weights, and other details are given. The huge 1962 Magadi colony involved the excavation of some 20,000 metric tons of soda mud. One egg is normally laid. Large numbers of birds tend to lay synchronously in particular parts of the colony. The threshold numbers for breeding may be of the order of 5,000 pairs. Both sexes incubate, for about 28–29 days. Incubating birds are liable to desert en masse when disturbed, e.g. by hyenas. 70–90% of eggs hatch, usually about 85%. Larger colonies are more successful than smaller, and birds that lay out of phase with others tend to desert without hatching. The development of the young resembles that of the Greater Flamingo, but the two are distinguishable at an early age by bill structure. At Lake Natron the fledging period is about 70 days, but at Lake Magadi it was about 90 days, probably because the parents had to fly to Lake Natron for food. Adults attend the chicks closely for the first week of life, but thereafter leave them increasingly. Chicks more than one week old gather in herds, which eventually aggregate to huge numbers, 300,000 or more. Both at Lake Natron and Lake Magadi the chicks moved en masse out of the breeding area to gathering grounds in shallow water, where they remained till able to feed themselves and fly. Both sexes feed the young with regurgigated liquid matter, delivered bill to bill with parent and young both facing forward, as in the Greater Flamingo. Feeding details were not closely observed at Lake Magadi as most feeding took place after dark. Breeding success has varied from 5 to 75%, averaging 41 to 43% of eggs laid. The 1962 Magadi colony had 33 to 38% breeding success. Mass moult to flightlessness is described. It may occur before, during, or after the breeding season, or without breeding, and normally only at Lake Natron. It lasts six to eight weeks, perhaps three weeks for an individual, and may be controllable in that it did not occur at Lake Magadi in 1962 when its effects would have been fatal for the colony. Predation by large mammals (from lions to jackals) and birds, especially Egyptian and other Vultures, is described and roughly quantified. Predation from all causes may have resulted in 5% loss at the Magadi colony, but at Lake Natron is probably less. Eight thousand young Lesser Flamingos and 80 Greater Flamingos were ringed at Lake Magadi in 1962. Ringing methods are described. Recoveries have been meagre, the most distant being from the Awash Valley, Ethiopia. No rings have been observed among the adult population in recent years. The most probable explanation of the poor results is ring loss through chemical action of the water.     

Important Bird Areas in Kenya

Bennun, L. & Njoroge, P. 2000. Important Bird Areas in Kenya. Ostrich 71 (1 & 2): 164–167.

The process of defining Important Bird Areas in Kenya has been underway since January 1995, with financial support from the Royal Society for the Protection of Birds. Literature review has proceeded in parallel with field surveys, which are still ongoing. Some 65 globally Important Bird Areas have so far been identified, and this total is likely to increase. Sites were intitially selected using the criteria of threatened species (37 sites) and congregatory species (15 sites). Additional sites were then identified for biome-restricted and restricted-range species, using information from the Bird Atlas of Kenya; these sites must form part of a regional set. Threatened species sites are concentrated in forests (on the coastal strip, in the central highlands and in western Kenya) and papyrus swamps. Congregatory-species sites are concentrated along the Rift Valley and the coast. The remaining sites are concentrated in semi-arid areas to the immediate north and east of the central plateau, and in highland forest on each side of the Rift Valley. No IBAs have yet been identified in the flat, arid north-eastern sector of the country. A large number of sites require additional protection and/or improved management. Particular priorities include several papyrus IBAs around Lake Victoria, among them Lake Kanyaboli and Yala and Sare Swamps, grassland pockets in Mungatsi and Nambale, Western Province; the Kakamega, South Nandi and North Nandi Forests; the increasingly fragmented coastal forests, including Arabuko-Sokoke Forest; and the Taita Hills. Information on the IBA process and its results is being distributed to decision-makers through a high-level IBA Advisory council, with encouraging intitial results.     

Pelagic zonation of water quality and phytoplankton in the Great Lakes

Analysis of aquatic ecosystem data collected from large water bodies must consider spatial variations. A suite of pelagic survey stations exists for the Laurentian Great Lakes, but little is known about their redundancy. We present a strategy to delineate the lakes into zones based on water quality and phytoplankton biovolume. Water samples were collected from 72 sites in two seasons (spring and summer) from 2007 to 2010 in all five lakes. Integrated samples were analyzed for phytoplankton biovolume and nine water quality parameters. We conducted cluster analysis, principal components analysis and non-metric multidimensional scaling methods for water quality and phytoplankton taxon-specific biovolume for the Great Lakes basin and for each lake separately. There were significant lake-to-lake differences, and based on lake-specific analyses, Lake Superior, Lake Michigan and Lake Erie were each divided into three zones; Lake Huron and Lake Ontario were each grouped into two zones. The zones identified by water quality and phytoplankton provide an understanding of spatial distributions for evaluating monitoring data.     

Seroprevalence of Alphavirus Antibodies in a Cross-Sectional Study in Southwestern Tanzania Suggests Endemic Circulation of Chikungunya

Background

To date, Alphavirus infections and their most prominent member, chikungunya fever, a viral disease which first became apparent in Tanzania in 1953, have been very little investigated in regions without epidemic occurrence. Few data exist on burden of disease and socio-economic and environmental covariates disposing to infection.

Methods

A cross-sectional seroprevalence study was undertaken in 1,215 persons from Mbeya region, South-Western Tanzania, to determine the seroprevalence of anti-Alphavirus IgG antibodies, and to investigate associated risk factors.

Results

18% of 1,215 samples were positive for Alphavirus IgG. Seropositivity was associated with participant age, low to intermediate elevation, flat terrain and with IgG positivity for Rift Valley fever, Flaviviridae, and rickettsiae of the spotted fever group. When comparing the geographical distribution of Alphavirus seropositivity to that of Rift Valley fever, it was obvious that Alphaviruses had spread more widely throughout the study area, while Rift Valley fever was concentrated along the shore of Lake Malawi.

Conclusion

Alphavirus infections may contribute significantly to the febrile disease burden in the study area, and are associated with several arthropod-borne infections. Their spread seems only limited by factors affecting mosquitoes, and seems less restricted than that of Rift Valley fever.     

Mycobacteriosis in the lesser flamingos of Lake Nakuru, Kenya.

In 1974, 51 debilitated lesser flamingos (Phoeniconaias minor) were easily captured at Lake Nakuru, Kenya. Nineteen (37%) of these had extensive mycobacterial lesions. Two years later it was difficult to locate any debilitated flamingos and no evidence of mycobacterial infection was found. Possible reasons for the high prevalence of mycobacteriosis in the 1974 collection are discussed.     

THE BREEDING OF THE GREATER FLAMINGO AND GREAT WHITE PELICAN IN EAST AFRICA

This paper brings together observations on the breeding of the Greater Flamingo Phoenicopterus ruber and Great White Pelican Pelecanus onocrotalus, mainly at Lake Elmenteita, Kenya, 1951–1971. The Greater Flamingo bred at Lakes Elmenteita and Nakuru in 11/21 observed years and at Lakes Natron and Magadi in 5/12 observed years. On average, it breeds about every second year, but a succession of breeding years is followed by several years in which no breeding occurs. A history of 21 years' breeding at Lakes Nakuru and Elmenteita is given. At Elmenteita three sites have been used, the main site in every breeding year, the others less often. The number of pairs breeding in any year has varied from 500–9,250, but in 1968 flamingos bred three times, involving perhaps 8,500 pairs which made about 15,700 nests, some pairs perhaps laying twice or even thrice in a year. Losses of eggs (38.2% overall) were caused by rising water (16.2%), competition for nest space with Great White Pelicans (6.9%, after 1968 only), human interference (3.5%), Marabou Stork predation (1.8%) and other natural causes (9.8%). Losses among chicks totalled 68.3% overall and were mainly due to Marabou Storks (36.5%), undiagnosed disease (8.6%), and rising water (6.6%). Disease caused serious loss only in 1966, and after 1968 losses from Marabous rose from 2.7% to 76.5%, resulting in an increase in overall mortality from 48.7 to 92%. This was perhaps associated with the establishment of a fish factory at Lake Naivasha. When attacking flamingo colonies Marabous did not actually eat many eggs or chicks, but simply caused wholesale desertion by alarming the flamingos. In 1968 total desertion of a colony of 4,500 pairs was caused between 18 and 26 March by a maximum of 17 Marabous, and similar wholesale desertion was caused in later years. The overall breeding success among Greater Flamingos at Elmenteita was about 19% of eggs laid, but without the excessive post-1968 Marabou predation would have been about 30%. At such a rate Greater Flamingos require at least 24 years of adult life to replace themselves, but if the mortality caused by Marabous since 1968 continues they will require about 58 years, and the population will inevitably decline. Breeding success at Lakes Magadi and Natron has been higher, about 44% of eggs laid; but figures available are much more approximate than at Elmenteita. Some new data on display, nest-site selection, laying dates, clutch-size, hatching and creche behaviour are given for the Greater Flamingo. The Great White Pelican bred at Lake Elmenteita from 1968 to 1971 without a break, some birds laying in every month, but with reduced laying November–December. They bred on the same islands as, and in association with the Greater Flamingo, and caused heavy losses among the latter, not through aggressiveness, but simply because of their superior size and weight. Although food supply must ultimately have controlled the pelican's ability to breed, an adequate food supply was available for 6 years before they did and continued after they had ceased. Their breeding was finally triggered by the Greater Flamingo colonies, with which the pelicans associated. When a flamingo colony was deserted because of Marabou Storks the pelicans, unafraid themselves of the Marabous, also deserted. They also associated with, and wiped out, a colony of Sacred Ibis. From July 1968 to June 1969 about 2,600 pairs of pelicans bred at Elmenteita, rearing about 2,200 young to the flying stage. The breeding colony apparently comprised most of the adults from Lake Nakuru and Lake Naivasha, the main feeding areas. From July 1968 to January 1971 certainly 7,200 and probably 8,000 pairs of pelicans bred at Elmenteita. Some pairs may have bred twice or thrice in this period. Breeding ceased suddenly in January 1971, eggs, and small and large young being alike abandoned for no established reason, although food supply was certainly still plentiful. Additional information on pair formation, incubation and fledging periods, nest-relief, etc. is given. The best available record of the incubation period is 35–36 days. Nest relief takes place on average about once every 48 hrs, and is dependent on thermal activity enabling the pelicans to soar. At Elmenteita large young ate quantities of putrefying matter, including the corpses of other young pelicans. They also ate living young hatching from eggs, and up to 14 days old. Touch probably plays an important part in helping them to locate possible food in opaque water.     

Why do flamingos stand on one leg?

A series of observational studies of captive Caribbean flamingos Phoenicopterus ruber were conducted to determine why flamingos rest on one leg. While frequently asked by the general public, this basic question has remained unanswered by the scientific community. Here we suggest that the latency of flamingos to initiate forward locomotion following resting on one leg is significantly longer than following resting on two, discounting the possibility that unipedal resting reduces muscle fatigue or enhances predatory escape. Additionally, we demonstrate that flamingos do not display lateral preferences at the individual or group levels when resting on one leg, with each bird dividing its resting time across both legs. We show that while flamingos prefer resting on one leg to two regardless of location, the percentage of birds resting on one leg is significantly higher among birds standing in the water than among those on land. Finally, we demonstrate a negative relationship between temperature and the percentage of observed birds resting on one leg, such that resting on one leg decreases as temperature rises. Results strongly suggest that unipedal resting aids flamingos in thermoregulation. Zoo Biol 29:365–374, 2010. © 2009 Wiley‐Liss, Inc.     

A study on an herbivorous fish, Oreochromis niloticus L., diet and its quality in two Ethiopian Rift Valley lakes, Awasa and Zwai

The natural food of Oreochromis niloticus from two Ethiopian Rift Valley lakes, Awasa and Zwai, was studied from the stomach contents. The food was analyzed to determine its chemical composition. The major consumed nutrient by the Awasa population was carbohydrate whereas in the Zwai population it was lipid. Microscopic identification revealed that Microcystis sp. and Botryococcus braunii are the dominant algae present in the food of the fishes from Lakes Zwai and Awasa, respectively. Assimilation efficiency of total organic matter is somewhat low, 28.3% for Awasa and 14.7% for Zwai populations. Both populations assimilated protein to a greater extent than other nutrients. In both lakes the quality of the food, expressed as a ratio of digestible protein to digestible energy, is adequate (>4 mg kJ ⁻¹) for growth, but the Awasa population appears to have higher growth and better condition.