Changes in pied kingfisher (Ceryle rudis) feeding related to endosulfan pollution from tsetse fly control operations in the Okavango Delta, Botswana.
Abstract
Diet, feeding behaviour and number of pied kingfishers (Ceryle rudis) were monitored on the Mochaba River in Botswana when the area was treated with aerosols of endosulfan at 6--12 g/ha to kill Glossina morsitans Westw. The kingfishers' diet comprised fish of 28--112 mm (mean 62 mm) total length and 0.2--19.1 g (mean 4.1 g) weight. Cichlids predominated, selectivity increasing with length. Kingfishers were attracted to fish kills where they fed faster, eating debilitated fish. The local fish population was substantially reduced by leaking endosulfan at 1 spray; kingfisher feeding rates fell and some birds left the area. The total concentration of endosulfan in the brains of 3 birds shot 2 weeks after the final spray was 0.2 mu g/g wet weight, similar to the levels found in the fish. When spraying ended, feeding rates had fallen from about 13 g/ha to about 6 g/ha, possibly because the availability of fishing perches and open water were reduced. The kingfisher population in the study area had apparently survived, and numbers at a communal roost were steady.