All birds of prey are unique, but accipiters are unquestionably the Porsches of the raptor world. Sure, falcons are fast, but can they turn on a dime to avoid a branch while flying through thick woods at high speed in pursuit of prey? Not hardly!
Accipiters, or forest hawks, have short, rounded wings and long tails that make them both fast and agile. Their characteristic flight is a series of rapid wing beats alternating with a glide. They fly swift and low through forests, maneuvering through the trees and brushy thickets where they will try to strike smaller birds that they flush from the trees and brush. When prey is spotted—usually other birds—accipiters accelerate with lightning-quick bursts of speed.
There are three species of accipiters in the United States and all three are found in Colorado: sharp-shinned hawks, Cooper’s hawks, and northern goshawks. In each, the females are larger than the males. Accipiters are more secretive than most other hawks. Since they eat mainly birds, one way to know if any are in the vicinity is to look for a "plucking post". This is a log, stump, or other structure upon which forest hawks pluck the feathers off their prey.
The jay-sized sharp-shinned hawk is the smallest of the three. This hawk gets its name from its flattened, thin "shins" or shanks. Birds make up to 90% of the sharp-shinned hawk’s diet, but they may also eat small mammals, frogs, lizards, and insects. The long tail feathers are all the same length, and the bird appears to have a square-tipped tail. Adults are slate-gray above, pale below, with fine rust-colored barring. Immature birds are brown above with whitish spots, creamy-white below with streaks on the breast, and have barring on flanks.
Male and female sharp-shinned hawks show a greater disparity in size than any other American hawk; the female is nearly twice the weight of the male. This can make it difficult to distinguish this bird from the middle-sized accipiters, the Cooper’s hawks. Cooper’s hawk is bigger, closer to the size of a crow, but the size of the male Cooper’s and female sharp-shinned overlap. Since there is great variation in plumage and in size for these two species, these hawks present a significant identification problem for many birders. The outer tail feathers are shorter than the inner feathers on Cooper's hawks, which gives a rounded tail. The Cooper’s legs are much thicker, and its head appears larger in proportion to the body than the sharp-shinned hawks. Cooper's hawks are barrel shaped, with the width of the chest fairly close in size to the width of the hips and the largest portion of the chest about halfway down the body. Sharp-shinned hawks, on the other hand, are widest at the shoulder and get distinctly narrower down to the hips.
There’s no mistaking the northern goshawk, the king of the accipiters. It is a larger, robust hawk, similar in size to a red-tailed hawk, with a wingspan of three-and-a-half to four feet. Renowned for their power and fearlessness, goshawks are tenacious in their pursuit of prey. If its prey seeks cover in a dense thicket, the goshawk often continues the chase on foot. They aggressively defend their nest sites and will dive at and even strike intruders with their talons. The call is a very distinguished, loud Kek-Kek-Kek.