Restoring Natural Biodiversity

Attu Island’s Rock Ptarmigan
Adapted from Steve Ebbert, Alaska Maritime Refuge

Rock ptarmigan (Lagopus mutus) occur throughout Alaska. Fourteen subspecies of rock ptarmigan are found in North America. Seven of the fourteen subspecies occur in the Aleutians, and six of these occur on only one or a few islands.

Official Species of Concern

Evermann's rock ptarmigan (L. m. evermanni) is an endemic subspecies and is recognized as a "species of special management concern" by the U.S. Fish and Wildlife Service. Once occurring throughout the Near Islands (Attu, Agattu, Shemya, Nizki-Alaid), Arctic foxes, introduced for fur production, eliminated ptarmigan on all but Attu. Bering Island, which is 300 miles to the West of Attu, supports another subspecies (L. m. ridgwayi).

Historical Range

Ptarmigan were reported on Agattu Island by the local Aleuts before 1886 but were not found there by Olaus Murie in 1936. Agattu is 27 nautical miles southeast from Attu Island's Massacre Bay, and is second only to Attu in size within the Near Island Group.

Meals for Alien Foxes

Non-native foxes wiped out rock ptarmigan from some Aleutian Islands but not on others. Shortly after arctic foxes were successfully introduced on Agattu in 1924 for fur production, ptarmigan disappeared. Arctic foxes were also released on 223,812-acre Attu, but ptarmigan survived, presumably because of extensive mountainous terrain available to breeding ptarmigan. Arctic foxes seldom use that habitat in the spring and summer. Agattu (55,535 acres), Amukta (12,425 acres) and Semisopochnoi (56,013 acres) are the only large islands where rock ptarmigan were eliminated by foxes in the Aleutians.

Attu Island - Last Stronghold

Today, Evermann's rock ptarmigan is confined to a single island, Attu, with an estimated population of 1,000 birds prior to the eradication of foxes there in 1999. Although nomadic elsewhere in Alaska, ptarmigan in the Aleutians are resident. Apparently birds have not crossed the pass between Attu and Agattu and re-established a population on their own. To restore them to areas once occupied prior to the coming of foxes, a program began in 2003 to capture birds on Attu Island and release them on Agattu island.

Insurance Against Extinction

Successfully establishing a breeding population on Agattu will increase the overall population of Evermann's subspecies and lessen their risk of extinction.