The southwestern red-tailed hawk (Buteo jamaicensis fuertesi) Website based on / supplement to book, is a subspecies of red-tailed hawk that breeds from northern Chihuahua to southern Texas. It winters in Arizona, New Mexico and southern Louisiana. This seems to be a particularly large subspecies, although its size is not drastically different from the western red-tailed hawk (B. j. calurus), and, going on average wing size and tarsal length, this appears to be the largest race of red-tailed hawk. The wing chord of males can range from , averaging , and, in females, it ranges from , averaging . Additionally, males and females average in tail length, in tarsal length and in culmen length.Preston, C. R. & Beane, R. D. (2009). "Red-tailed Hawk (Buteo jamaicensis)". The Birds of North America. .Ridgway, R. & Friedmann, H. (1919). The Birds of North and Middle America: A Descriptive Catalogue of the Higher Groups, Genera, Species, and Subspecies of Birds Known to Occur in North America, from the Arctic Lands to the Isthmus of Panama, the West Indies and Other Islands of the Caribbean Sea, and the Galapagos Archipelago. Vol. 50, No. 8. Govt. Print. Hybridization seems to occur in eastern Texas with the eastern red-tailed hawk (B. j. borealis), broadly to the west with B. j. calurus and, possibly, in Nuevo León and Chihuahua with the Mexican Highlands red-tailed hawk (B. j. hadropus).Palmer, R. S. ed. (1988). Handbook of North American Birds. Volume 5 Diurnal Raptors (Part 2). This race combines the darker back of B. j. calurus with the paler underside of B. j. borealis, with the belly band either entirely absent or only manifesting in light streaking. The tail is variable but relatively pale, with some individuals showing almost no dark subterminal band, others having quite a broad subterminal band and some showing extensively barring on top like darker morphs of B. j. calurus.
