Extreme color variation in the Peregrine Falcon (Falco peregrinus) in Patagonia

Abstract

From fieldwork begun in 1979 and continuing intermittently until the present, we show the range in variation in pigmentation of Peregrine Falcons (Falco peregrinus) native to the Patagonian region of South America. This variation nearly equals the full range in Peregrine Falcon color variation for all races worldwide. The pallid morph is paler than any other peregrine, and in extreme southern Patagonia, most dark or normal morph adults are as pale or paler than extremely pale arctic peregrines from northern Asia and North America. In the forests of the southern Andes Mountains, there are richly colored (i.e., with deep red-brown ventral background pigmentation) falcons that approach or equal the darkest peregrines anywhere. Some juvenile peregrines are more deeply red-brown ventrally than any other juveniles worldwide. Most important, we introduce the hypothesis that non-pallid adult color variants are largely segregated by habitat type. By inference, this suggests that adjacent ecotypes may represent different subspecies.