Decline of Raptors over a Three-Year Period in Laikipia, Central Kenya

Abstract

Raptors were monitored monthly over a three-year period in a protected area in central Kenya. The number of raptors declined more than 40% per year. Scavenging birds accounted for most of the decline; sightings decreased by 70% during our surveys, although these declines were not statistically significant. During the time of the study, the overall populations of large wild herbivores showed little change, whereas domestic herbivores, particularly sheep and goats, increased markedly, suggesting that food limitation was not the cause of the vulture declines at the study site. Possible causes of raptor decline include the consumption of poisoned baits, which are placed by pastoralists to kill large predators that attack livestock. Scavenging birds provide one of the most important yet underappreciated ecosystem services of any avian group. The rapid decline of scavenging birds, especially vultures, in central Kenya warrants additional population monitoring to understand whether declines are local or regional, and to elucidate causes of population decreases.