Geographic information system-based modelling of vulture response to carcass appearance in the Caucasus


A. Gavashelishvili. Current address: 3420, 16th St. NW#404, Washington, DC 20010, USA.


Factors influencing the response of griffon Gyps fulvus, cinereous Aegypius monachus and bearded Gypaetus barbatus vultures to carcass appearance were studied in the Republic of Georgia by observing 100 new carcasses for 10 days. It was observed that 92–97% of the time cinereous (n=25) and griffon (n=47) vultures fed on carcasses within 4 days of their appearance, whereas 97% of bearded vultures fed within 6 days (n=32). In cases where all three species fed at a carcass, cinereous vultures were the first to arrive, followed by griffon vultures and then bearded vultures. The probability that all three species would eat a carcass was positively correlated with visibility within 100 m of the carcass and mean distance to roads within 5 km. The probability that griffon and cinereous vultures would feed increased with extent of open areas within 5 km of a carcass. Griffon and bearded vultures' response to carcass appearance was positively related to mean slope within 5 km of a carcass. In addition, the probability that griffon vultures would feed was negatively correlated with the distance to the nearest populated area from the carcass. The heavier the carcass and farther it was from roads, the sooner griffon vultures landed at it, and the presence of ravens Corvus corax at a carcass appeared to be a signal to the vultures of relative security. The probability that cinereous vultures would feed on a carcass was negatively correlated with mean annual rainfall within 5 km of the carcass. Cinereous vultures landed sooner at carcasses that were farther from populated areas. Bearded vultures landed sooner at smaller carcasses that were farther from populated areas and from bearded vulture nests. These models can be used to help identify foraging areas important to vultures in the Caucasus and elsewhere, and thus help focus conservation efforts and avoid conflicts between vulture conservation and other activities.