The gyrfalcon is the largest falcon in the world, and gyrfalcons live in the far north, in the Arctic, where they are top predators. 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, and Alaska Department of Fish and Game gives females as weighing about 1,200 to 2,100 grams. A large female gyrfalcon from eastern Siberia was found to weigh 2,600 grams. Among standard measurements of gyrfalcons, the culmen is 2 to 2.8 centimeters.

In a study in central west Greenland, time-lapse video cameras at three gyrfalcon nests recorded 2,677.25 hours of nestling video. The Peregrine Fund reported that cameras at gyrfalcon nests collected 1.5 million photos over five years, as of 2019. Researchers on the Seward Peninsula use motion-activated cameras at nests to see the prey that is brought back.

Alaska biologists fly slowly past mapped nest cliffs by helicopter and check whether raptors are using them, without landing.

Biologists on the Seward Peninsula band gyrfalcon chicks when they are about 25 days old so the birds can be identified in the future.

In July 2012, biologists collected 854 molted gyrfalcon feathers from 58 nest cliffs on the Seward Peninsula for genetic analysis.

Gyrfalcons eat mostly other birds, and ptarmigan are the gyrfalcon's main food. Prey numbers strongly influence the breeding success and density of gyrfalcons. Cameras at nests on the Seward Peninsula showed that gyrfalcons rely heavily on ptarmigan but also change their diet when ptarmigan numbers drop. A gyrfalcon also eats waterfowl and seabirds, and some small mammals, such as ground squirrels and hares.

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

The gyrfalcon seems to have escaped the severe declines in birds of prey that DDT caused in the last half of the 20th century. Audubon's field guide, read in 2026, says North American gyrfalcon populations are probably stable, though the bird has declined in parts of arctic Europe. As of 2026, the IUCN Red List lists the gyrfalcon as Least Concern.

In European falconry, the gyrfalcon was reserved for kings and nobles. There is evidence of gyrfalcons being tamed in Scandinavia from the seventh century onwards. Falconry is one of the oldest sports, dating back some 4,000 years.

Between about one and five gyrfalcons are taken from nests in Alaska each year for falconry, in a highly regulated way, as of 2020.

The mean size of 100 clutches of gyrfalcon eggs on the Yukon-Kuskokwim Delta was 3.43 eggs. Gyrfalcons often return to the same nest site year after year, and gyrfalcons that nest in the Arctic often start laying eggs while the temperature is still below freezing. The eggs take about five weeks to hatch.

Gyrfalcon chicks hatch at a weight of around 52 grams. 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.

Gyrfalcons cached and re-delivered at least 9.1 percent of the items they brought to nests in a west Greenland study.

Words to know

• culmen: upper beak ridge
• molted: shed
• clutches: sets of eggs
• raptors: birds of prey
• ptarmigan: a bird