Plumage is extremely variable, ranging from very light forms to very dark forms. The "typical" color phase is dark brown above and white below, with a band of dark speckling across the belly (belly band), and a rusty-red tail (paler underneath). Flying birds are white with brown barring underneath, dark brown edges around the wings, and dark brown shoulder patches. The dark belly band is easiest to see in flying birds. The western race of Red-tailed Hawks is darker with more streaking than the typical phase. Krider's Red-tailed Hawk is a very pale race found in the Great Plains, including eastern Montana. These are light mottled brown above and nearly pure white below. The belly band is often indistinct or absent, and the tail is usually light rust above and creamy below with faint barring. Harlan's Red-tailed Hawk (formerly considered a distinct species) is dark mottled brown above, and light brown and white streaked below, with a brown barred tail. They breed in northern Canada and Alaska, and are seen in Montana only during migration. All of these races can have light and dark individuals (color phases). The dark (melanistic) color phase is much less common than the light color phase. Melanistic Red-tailed Hawks have a dark brown belly, and dark brown wing "arms," with light flight feathers, giving their wings a two-toned appearance from underneath. The immature Red-tailed Hawks of all color phases and races look similar to the adults, except they have brown barred tails and more brown streaking over the rest of their bodies. Red-tailed Hawks range in length from 19 to 25 inches, and have a wingspan of 46 to 58 inches.
For a comprehensive review of the conservation status, habitat use, and ecology of this and other Montana bird species, please see Marks et al. 2016, Birds of Montana.
Krider's Red-tailed Hawks are easily mistaken for Ferruginous Hawks, but they have white feathering on the legs (Ferruginous Hawks have dark feathering on the legs). Rough-legged Hawks of all ages and color phases have a white tail with a black terminal band, instead of the rust or brown tail of the Red-tailed Hawk. Swainson's Hawks have a chestnut-brown bib, but no belly band, and have dark-colored flight feathers instead of light ones.
Western Hemisphere Range
Red-tailed Hawks migrate to the southern United States for the winter, although some winter in Montana. Bozeman area: March 20 to May 10 and August 28 to October 25. Harlani and kriderii occur mainly as migrants.
Red-tailed Hawks nest in trees and on cliffs, and hunt over grasslands, open woodlands, and agricultural areas.
Red-tailed Hawks eat primarily ground squirrels and other small rodents, but also feed on a wide variety of other animals. Red-tailed Hawks often eat snakes, including rattlesnakes.
Numbers decreasing in Fortine area. Light phase reported most often. In Gallatin valley, 11.6% of pairs non-breeding; territories ranged from 2.6 to 4.6 sq.km.
One to three eggs are laid in April. Incubation lasts about a month. The young fly in June or July when 6 to 7 weeks old. Incubation seen April 19; hatching late June; young still in nest late July. In Gallatin valley, 53% of nests successful, average 2.34 young fledged. Infertility loss = 3.7%; nesting mortality = 5.9%.