The gyrfalcon is the largest falcon in the world, and it is somewhat larger than a peregrine falcon. Gyrfalcons live in the far north, in the Arctic. They are top predators there. Gyrfalcons are one of four falcon species that breed in Alaska.

Animal Diversity Web gives an average total length of 53 centimeters for male gyrfalcons and 56 centimeters for females. A male gyrfalcon weighs about 800 to 1,350 grams. Alaska Department of Fish and Game gives females as weighing about 1,200 to 2,100 grams. A female is bigger than a male.

A gyrfalcon hunts by scanning from a high rock perch or while flying. While hunting, it uses keen eyesight to spot potential prey. A gyrfalcon often hunts by flying fast and low over the ground. It usually hunts in a level chase rather than a steep dive, and it may chase its prey over long distances.

Gyrfalcons eat mostly other birds. Ptarmigan are the gyrfalcon's main food. A gyrfalcon also eats waterfowl and seabirds, and some small mammals, such as ground squirrels and hares.

Gyrfalcons come in white, gray, and dark forms, called morphs. White gyrfalcons are found mainly in Greenland.

In winter some gyrfalcons move south, and some stay in their territories. In winter a few gyrfalcons come south to the northern edge of the United States.

Male gyrfalcons begin defending a nesting territory in mid-winter. Gyrfalcons often return to the same nest site year after year. A gyrfalcon does not build its own nest and nests on cliffs. Some gyrfalcons use an old nest that another bird, such as a raven, built, and sometimes a gyrfalcon lays its eggs on a bare cliff ledge with no nest.

A gyrfalcon usually lays three or four eggs, and the eggs take about five weeks to hatch. Adult gyrfalcons bring food to the nest for their young. Young gyrfalcons begin short practice flights at about five weeks old and spend the next eight weeks or more honing their flying. At 3 to 4 months old, young gyrfalcons become independent of their parents.

Words to know

• ptarmigan: a bird
• perch: a high seat
• morphs: color forms
• independent: on their own