Distributions of the Galápagos (Buteo galapagoensis) and Swainson's hawks (B. swainsoni). The Galápagos Islands (inset) are located on the equator about 1000 km off the coast of South America. The archipelago is volcanic in origin and there is no evidence that it has ever been connected to the mainland. The Galápagos hawk has breeding populations on all the gray-filled islands; breeding populations have been extirpated from Santa Cruz, San Cristóbal, and Floreana. The Swainson's hawk distribution is from . While the majority of Swainson's hawks overwinter in Argentina, some winter in the southern United States and Mexico.
Bollmer et al. BMC Evolutionary Biology 2011 11:143 doi:10.1186/1471-2148-11-143