Responses of raptors to habitat fragmentation : from individual responses to population susceptibility
Habitat fragmentation has different effects on species and communities, depending on a suite of life-history and population traits: some species are more vulnerable to the effects of fragmentation than others. Contrasting responses suggest there are particular species' attributes that make an organism more or less susceptible to the effects of fragmentation. Much research has focused on identifying which of these traits are the most useful indicators of a species' fragmentation-linked extinction risk. For example, body size, rarity, ecological specialization, matrix use, range size and turnover rate have all been linked with species extinction risk. Few studies have, however, attempted to explore the traits that predispose raptors to vulnerability from fragmentation. In this study, I compare the responses of two near-sympatric raptors (the Black Harrier Circus maurus and the Black Sparrowhawk Accipiter melanoleucus) to habitat fragmentation. On a broader scale, I use a simple model of susceptibility to fragmentation effects, and a sample of hawks (Accipiter spp) and harriers (Circus spp) in the family Accipitridae, to predict which species attributes are most likely to produce a negative response to habitat fragmentation. I then compare these predictions with the current global threat status of each species to test whether the model can predict threat status with acceptable accuracy.
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Percy FitzPatrick Institute of African Ornithology