Nesting association of raptors and buff-necked ibis in the Argentinean Patagonia

We observed six species of raptors: Black-chested Buzzard-eagle (Geranoaetus melanoleucus), Cinereous Harrier (Circus cinereus), Red-backed Hawk (Buteo polyosoma), Chimango Caracara (Milvago chimango), Crested Caracara (Polyborus plancus), and Peregrine Falcon (Falco peregrinus), nesting at Buff-necked Ibis (Theristicus caudatus) colonies in northern Argentinean Patagonia. Four out of these six species preyed upon Buff-necked Ibis nestlings and eggs. Ibis breeding success was not different when raptor species were present or absent from colonies. The association between raptors and ibises could be a consequence of generally low availability of colony sites where raptors are absent.