Spatio-temporal segregation of facultative avian scavengers at ungulate carcasses

摘要

Spatial and/or temporal segregation of resource use are mechanisms that may allow coexistence betweenpotential competitors. Spatial and temporal patterns of carrion use were studied in the main avianscavengers of Sierra Espuna Natural Park (SE, Spain). We monitored the use of ungulate carcassesprovided by hunting during winter and summer of 2005-2006. Non-breeding ravens exploited aggre-gated carcasses and depleted the resource in a few days while golden eagles used scattered carcassesover a longer consumption period. Moreover, non-breeding ravens exploited carcasses when goldeneagles were less active. Almost all available hunter kills were exploited by golden eagles and/or ravensduring winter whereas a high number of carcasses were not used during the breeding season, suggestingstrong competition in a period of low food availability. Thus carrion arrangement, seasonal behaviourand competitive interactions could be affecting the foraging patterns of these two species. Interestingly,intraspecific aggregation of the smaller species and dominance of the larger one may act on the use ofshared resources and trigger segregation mechanisms. Our results support that differences in the spatialand temporal patterns of resource use may allow resource partitioning between two species, thusfacilitating their coexistence in sympatric areas.