The Red-tailed Hawk is a common and widespread North American raptor, often spotted silently stationed in a tree searching for unsuspecting prey. You may hear one before you see it – listen for the bird’s signature vocalization (download a Haikubox recording here), described as a “scream” by the Peterson Field Guide to Bird Sounds.
The Red-tailed Hawk call is consistent across their range, unlike their feather coloration which can vary widely. This plumage polymorphism means they have several distinct color variants, even within the subspecies.
Researchers have developed several hypotheses which may explain polymorphism, including apostatic selection (prey will not recognize a less common morph and can be caught more easily), disruptive selection (certain habitats and environments select for a particular morph), and nonrandom mating (individual hawks prefer mates of the same morph).
Looking ahead, The Red-tailed Hawk Project and other researchers hope to better understand Red-tailed Hawks and how plumage coloration impacts the birds’ health and survival.