Alaska's Peregrine Falcons: What Their Genes Say About Subspecies

A peregrine falcon on the nest with chicks. Image from the National Park Service's page.

How the peregrine falcon (Falco peregrinus) should be split into subspecies has long been argued over. The subspecies are defined partly by plumage colour, which varies a great deal, and local groups may drift apart because birds tend to return to breed where they were raised. In North America the picture is muddied further by the captive-bred peregrines, some from non-native stock, released to restore populations after the mid-20th-century crash caused by organochlorine pollution.

Why Alaska

Alaska holds all three named North American subspecies, broadly by habitat:

And unlike elsewhere, Alaska's peregrines were never supplemented with captive-bred birds during the late-20th-century recovery, so their genes reflect natural history.

What the study found

A 2017 study in PLOS ONE compared mitochondrial DNA sequences and microsatellite markers from Alaskan peregrines:

• Arctic and boreal birds could not be told apart genetically.
• Coastal pealei birds were distinct from both, and split into eastern and western populations.
• Gene flow between anatum and tundrius was generally higher than between pealei and either of them.
• Genes also flowed between Canada's supplemented populations and Alaska's unsupplemented ones.

Without formally revising the taxonomy, the authors suggest that peregrines in Alaska and along the North Pacific coast form two regional groupings, a coastal one (pealei) and a boreal-and-Arctic one (now anatum and tundrius), each made up of separate populations connected to one another to varying degrees.

Sources

• National Park Service, Yukon-Charley Rivers National Preserve, "High-latitude Peregrine Falcons." https://www.nps.gov/articles/hilatpefa.htm
• Talbot, S. L., G. K. Sage, S. A. Sonsthagen, M. C. Gravley, T. Swem, J. C. Williams, J. L. Longmire, S. Ambrose, M. J. Flamme, S. B. Lewis, L. Phillips, C. Anderson, and C. M. White. 2017. Intraspecific evolutionary relationships among peregrine falcons in western North American high latitudes. PLOS ONE 12(11): e0188185.
• Corrected: "organochloride" to "organochlorine".
• Words on this page from people and organisations outside the federal government are paraphrased; rewritten in hubnx's own words.