The adaptations of the Rough-legged Hawk (Buteo lagopus) are as helpful as they are mysterious. Named for the feathers that keep their legs warm all the way to their toes (lagos is Greek for rabbit and pes is Latin for foot), this hawk is properly prepared for life in the north. Rough-legged Hawks migrate from the arctic to the northern plains for winter months and are often seen soaring above open grasslands looking for small mammals to eat, their wings and tails spread wide. This pose, captured by Dennis Lingohr in the photo above, also showcases their dark feather “fingers” reaching for the sky – a strategy to help the birds reduce speed and stay afloat when scouting for meals.

So what’s the mystery? Like only a few other bird species (such as Swainson’s and Ferruginous Hawks), Rough-legged Hawks are known for their plumage polymorphism. This means that the birds can range in color from light to almost completely black because of genetic mutations. The different categories of colors are called morphs, and no one really knows why or when these morphs began. Rough-legged Hawks have eight color variations between males and females and adults and juveniles, making identification very tricky! With its bright eyes, lack of underwing markings and smudgy gray tail band, the light-morph in this month’s photo is likely a juvenile.

You can observe hundreds of other birds on the prairie over the course of a year. Download our simple birding checklist to get started: American Prairie Birding Checklist.