naturebriefs
8:40in productionCh. 1 · Size and dimorphism/ 8:40 · ceiling 15 min
Birds · Evolution

Gyrfalcon

The gyrfalcon is not a symbol—it’s a white-to-grey Arctic predator that hunts ptarmigan on sea ice and carries climate change in its genes.

The gyrfalcon is the largest falcon species, a high-latitude resident of Arctic coasts and tundra across northern North America and Siberia, exhibiting marked sexual dimorphism and extreme plumage polymorphism (white to dark grey-brown morphs). It preys on ptarmigan, waterfowl, fish, and small mammals; was formally described by Linnaeus in 1758; and is currently classified by the IUCN as Least Concern. Its size, plumage variation, and ecological niche—including winter use of sea ice and competition with peregrines under climate change—are empirically documented. Molecular work links plumage colour to the MC1R gene, and population genetics reveal clinal allele distributions shaped by long-distance dispersal and local selection pressures like nesting chronology in Greenland.

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Chapters & takeaways4
  1. 1:02
    Size and dimorphism

    It is the largest falcon—and the female is much larger than the male.

  2. 2:15
    Range and movement

    It breeds on Arctic coasts and tundra—but some individuals wander far in winter.

  3. 3:40
    Colour and diet

    Its plumage ranges from all-white to dark grey-brown—and it hunts ptarmigan, waterfowl, fish and small mammals.

  4. 5:09
    Taxonomy and measurement

    Linnaeus named it Falco rusticolus in 1758—and males measure 48–61 cm and weigh 805–1,350 g.

Worth your time?

Yes. See the whole thing.

4.5/ 5
What works
  • links plumage to MC1R gene
  • shows clinal allele distributions shaped by dispersal and local selection
  • confirms size and dimorphism against falconid norms
  • documents winter use of sea ice
What does not
  • establish lifespan
  • specify clutch size
  • give population figures
  • detail predator-prey dynamics beyond prey types
See it if
  • field ornithologists
  • Arctic ecologists
  • geneticists studying adaptation
Skip it if
  • general birdwatchers outside its range
  • conservation practitioners needing urgent intervention data
The written brief1 min read

What the species is and where it came from

The gyrfalcon (Falco rusticolus) is the largest species in the falcon family. Carl Linnaeus formally described it in 1758. It is a high-latitude resident of Arctic coasts and tundra across northern North America and Siberia.

How it works, in terms someone would actually use

It hunts ptarmigan and waterfowl in flight, and also takes fish and small mammals. It breeds on Arctic coasts and tundra, and on islands of northern North America and Siberia. Some individuals disperse widely after breeding or in winter.

What it gets right

It gets right the link between morphology and environment: extreme plumage polymorphism (white to dark grey-brown morphs) matches regional snow cover and substrate; sexual dimorphism (female much larger than male) aligns with falconid norms; size (males 48–61 cm, 805–1,350 g) confirms its status as the largest falcon.

What it does not

It does not establish a lifespan, clutch size, population figure or conservation threat beyond IUCN Least Concern. It does not specify migration routes, winter range limits, or predator-prey dynamics beyond prey types listed.

What it changed

It reveals how plumage colour maps to the MC1R gene, and how clinal allele distributions reflect long-distance dispersal and local selection—such as nesting chronology in Greenland.

Who it is for, and who it is not

It is for field ornithologists, Arctic ecologists, and geneticists studying adaptation. It is not for general birdwatchers outside its range, nor for conservation practitioners needing urgent intervention data.

Is it worth your time

Yes—if you are in the Arctic or sub-Arctic and want to see the largest falcon species hunting over sea ice or tundra. It is not worth seeking elsewhere unless you are tracking vagrants.

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10:16
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