Effects of drift sprays of endosulfan, applied for Tsetse-fly control, on breeding little bee-eaters in Somalia

Feeding behaviour and breeding success in an insectivorous bird, the little bee-eater Merops pusillus, were monitored in an area of southern Somalia treated five times with drift sprays of the insecticide, endosulfan, applied at 14–41 g ha⁻¹. Birds fed mainly on bees and wasps but flies and beetles were also commonly eaten. After the heaviest spray application day-flying insects virtually disappeared from one area for 24h; the feeding rate fell and breeding failure at three nests followed. However, at the end of the spraying operation, fledging success in the sprayed area was generally the same as outside. Disrupted laying and incubation, and co-operative breeding amongst little bee-eaters in Somalia, may indicate a poor food supply and a population particularly vulnerable to insecticidal treatments.