Food sources and foraging tactics in tropical rain pools

Pools on exposed rocks are common over much of Africa. Based on dimensions and position, those examined are of three types. Each type is inhabited by larvae of virtually a single dipteran species at high densities (over two million larvae m−2). Location of the pools suggests that food might be a limiting factor. However, events, including defecation in pools by civets and genets, fruit fall and wind-bornepollen, apparentlyensure that this is not the case. In this environment of superabundance animals are presumably free to choose favoured items of food. Each aninial species does, indeed, take a characteristic assemblage of food items. However, each species is shown to eat whatever it can swallow, differences in gut contents being due to differences in tlic clratactctisric food iterns available in each type of pool. Most algae are excluded because they are too largc or inaccessible, which means that the pool food chains are based largely on allochthonous detritus. There is no reason to believe that food type, perse, has any influence in determining which of the three dipteran species is present.