PREY DIVERSITY AND SELECTIVITY OF THE AFRICAN FISH EAGLE - DATA FROM A ROOST IN NORTHERN KENYA

A total of 1872 bones from a fish eagle roost at Lake Turkana, Kenya w as identified and analysed to provide data on fish eagle prey and diet , The approach of this study complements field observation studies in that it provides a long-term analysis and quantification of the diet, rather than short qualitative observations, The study found that, at l east where fish is relatively abundant, fish eagles are both selective and opportunistic: selective in taking preferred fish in much greater proportions than natural availability, and also in avoiding unwanted fish regardless of abundance, but opportunistic in taking certain othe r species in proportion to their availability. They also show consider able selection in size and habitat preferences of prey, Non-fish prey forms a considerable proportion of the diet, and probably represents b oth opportunistic hunting, possibly when conditions for fishing are po or, and killing of other predators robbing fish eagle nests, As well a s describing and quantifying the fish eagle diet at Lake Turkana, data from this study suggest that further study is needed to quantify the impact of fish eagle predation on Clarias lazera, a rare, but valuable species to the Lake Turkana fishery. The study of bird roost prey rem ains also provides baseline data for studies of fossil microfaunal acc umulations. Scatters of bones under fish eagle roosts are common in ea stern Africa, and undoubtedly contribute to many of the fossil bone ac cumulations recovered, One of us (DM) has noted that the taxonomic and skeletal composition of the Koobi Fora roost bears a great resemblanc e to some of the clusters she is analysing from Olduvai Gorge, Further similar studies will provide additional data on bird roost accumulati ons.