The gyrfalcon is the largest falcon in the world, and gyrfalcons live in the far north, in the Arctic, where they are top predators. No living subspecies of the gyrfalcon are currently accepted.

As of November 2026, a study of falcon genetics suggests gyrfalcons may have evolved from eastern saker falcons.

Gyrfalcons come in white, gray, and dark forms, called morphs, and gyrfalcon plumage color is associated with the melanocortin 1 receptor gene. In Greenland, a demographic study suggested that white gyrfalcons and white pairs laid eggs earlier in the breeding season and produced more offspring. White gyrfalcons are found mainly in Greenland.

A study of 48 gyrfalcons tagged with satellite transmitters in Greenland from 2000 to 2004 found a winter behavior not known before: birds winter on sea ice far from land. A satellite-tracked young female gyrfalcon travelled over 4,548 kilometers in about 200 days of winter, spending over half that time over the ocean between Greenland and Iceland. Winter home ranges of gyrfalcons tagged in Greenland were 383 to 6,657 square kilometers on the west coast and 26,810 to 63,647 square kilometers on the east coast.

Animal Diversity Web gives an average total length of 53 centimeters for male gyrfalcons and 56 centimeters for females. A large female gyrfalcon from eastern Siberia was found to weigh 2,600 grams.

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

The gyrfalcon feeds mainly on ptarmigan, especially early in the breeding season, and its distribution is closely connected with where ptarmigan live. Researchers believe the local supply of ptarmigan plays an important role in the dispersal and survival of gyrfalcons. Prey numbers strongly influence the breeding success and density of gyrfalcons. On the Yukon-Kuskokwim Delta, ptarmigan made up 58 percent of the prey items at 15 nest sites in the Askinuk Mountains.

The Peregrine Fund says gyrfalcons have been studied in isolated pockets for centuries, in part because falconers have prized them.

Alaska biologists fly slowly past mapped nest cliffs by helicopter and check whether raptors are using them, without landing, and they had two observers each survey historic nest sites to estimate how well different observers see nests. In July 2012, biologists collected 854 molted gyrfalcon feathers from 58 nest cliffs on the Seward Peninsula for genetic analysis.

On the Yukon-Kuskokwim Delta, between 2000 and 2004 at least 71 to 80 percent of monitored gyrfalcon territories were occupied each year, and researchers know of 79 nesting territories in a region of 130,000 square kilometers as of January 2011. On the Seward Peninsula, about 70 to 80 pairs of gyrfalcons nest, about one-tenth of Alaska's total, as reported in 2020. Gyrfalcon territories on the Yukon-Kuskokwim Delta were 3.70 to 5.49 kilometers from their nearest neighbors on average in three study areas.

A 2020 summary of 24 Arctic falcon monitoring sites found that peregrine falcon and gyrfalcon populations are generally stable, and also found gaps in coverage. Biologist Travis Booms said in 2020 that gyrfalcons may be declining locally in western Alaska and the Yukon Territory. 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.

The gyrfalcon has been less affected by DDT and other pesticides than the peregrine falcon.

The mean size of 100 clutches of gyrfalcon eggs on the Yukon-Kuskokwim Delta was 3.43 eggs, and 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. Tracked young gyrfalcons in Sweden stayed near the nest until late August, and juvenile gyrfalcons tagged with satellite transmitters in the Swedish mountains had a median pre-dispersal home range of 266 square kilometers, which varied greatly.

Words to know

• morphs: color forms
• plumage: feather coat
• transmitters: tracking tags
• dispersal: spreading out
• raptors: birds of prey