This winter’s Gray-crowned Rosy-Finches flock on the Homer Spit has numbered about 40-50 since they first arrived in November. If you look carefully through the flock you might pick out one bird that is a bit different from the rest. The race of Gray-crowned Rosy-Finch that regularly winters on the Homer Spit is the Kenai Peninsula breeding littoralis, however, this winter there is also one finch of the interior Alaska breeding race tephrocotis in the flock. Last winter there were no reports of tephrocotis on the Spit. While during the winter of 2008-2009 there were at least 15 tephrocotis in the flock.
Four subspecies of Gray-crowned Rosy-Finch Leucosticte tephrocotis occur in Alaska (Gibson and Kessel 1997). These four subspecies can be grouped into two easily identifiable forms or types–coastal “gray-cheeked” and interior “brown-cheeked” forms. Two of the four subspecies, littoralis and tephrocotis are regularly found in Homer in the winter, and we should be on the lookout for the Aleutian Gray-crowned Rosy-Finch, griseonucha, which might rarely occur.
Interior form:
L. t. tephrocotis: In Alaska the interior form is comprised of just one subspecies, nominate tephrocotis. It is known as the “Interior” Gray-Crowned Rosy-Finch or “Cassin’s” Gray-crowned Rosy-Finch. In Alaska it breeds in the Brooks Range, in the mountains between the Yukon and the Tanana Rivers, and in the White Mountains (Gabrielson and Lincoln 1959). It winters from southern British Columbia, central Alberta, southern Saskatchewan, and southwestern Manitoba south through the Rocky Mountains and Great Basin (AOU 1957). It is sometimes found wintering in small numbers in coastal Alaska, where small numbers are usually mixed in the larger flocks of littoralis Rosy-Finches.
Coastal form:
The Coastal form is comprised of three subspecies in Alaska, all of which have an entirely gray crown and cheek.
L. t. littoralis: Is variably called the “Coastal,” “Hepburn’s,” or “Gray-cheeked” Rosy-Finch. In Alaska it breeds in the mountains of Central, Southcoastal, and Southeast Alaska. Wintering flocks can be encountered at feeders and beaches throughout coastal Alaska from the Kenai Peninsula south through Southeast Alaska. The Homer spit usually hosts a winter flock of 100+ birds.
L. t. griseonucha: Is known as the “Aleutian” Rosy-Finch. It occurs from the Kodiak Archipelago and the outer end of the Alaskan Peninsula west through the Aleutian Islands. The Aleutian Rosy-Finch is primarily non-migratory, but winter movements to lower elevations occur as well as occasional wanderings further east, possibly the Kenai Peninsula where it should be looked for in winter (especially on the Homer Spit). Gibson and Kessel (1997) include ‘kadiaka’ in the subspecies griseonucha. ‘Kadiaka’ is resident on Kodiak Island and is intermediate in size between littoralis and griseonucha. Gabrielson and Lincoln (1959) considered it a separate race.
L. t. umbrina: Is known as the “Pribilofs” Rosy-Finch and is a year-round resident on the Pribilof Islands and St. Matthew Island. It is the largest and darkest of all of the subspecies.
Distinguishing the three subspecies from each other is less straight forward than telling an interior bird from a coastal bird. The main differences between the three coastal subspecies include: size, darkness of brown breast, amount of contrast between the breast and the throat, extent of black streaking on the back, and bill shape. Distinguishing littoralis from griseonucha where their winter ranges come together may not be possible in the field.
See the photos below for information on how to identify the races of Gray-crowned Rosy-Finch. Click on any photo to enlarge.
Gray-crowned Rosy-Finch L. t. littoralis and tephrocotis (center), Homer Spit, Homer, 20 December 2010.
The bird in the center of the flock (looking straight at the camera) is an interior tephrocotis. It is identified primarily by its brown cheeks; the gray on the head is limited to a broad supercilia that reaches around to the back of the head. Also, the brown breast is slightly paler brown than that of the littoralis finches which surround it.
“Hepburn’s” Gray-crowned Rosy-Finch L. t. littoralis, Homer Spit, Homer, 20 December 2010.
On all three subspecies that comprise the coastal form the entire sides of the face, including the cheek, is gray. The breast on these littoralis Gray-crowned Rosy-Finches is dark brown which contrasts with the black throat. Since Gray-crowned Rosy-Finches nest in extremely cold and rugged environments we can’t assume from the snow that it’s winter. However, the yellow bills give the season away. Breeding plumaged birds of all subspecies have black bills.
“Interior” Gray-crowned Rosy-Finch L. t. tephrocotis, Homer Spit, Homer, 20 December 2010.
Note the brown cheeks, lighter brown breast than a littoralis, and stout bill.
Gray-crowned Rosy-Finch L. t. littoralis and tephrocotis, Homer Spit, Homer, 20 December 2010.
The flash of their silvery underwings as a flock takes flight is one of my favorite field marks of a Rosy-Finch.
“Aleutian” Gray-crowned Rosy-Finch L. t. griseonucha, Adak Island, 14 May 2010.
Aleutian breeding Gray-crowned Rosy-Finches are larger, darker breasted and longer billed than littoralis. The bills of all Rosy-Finches are black during the breeding season.
“Aleutian” Gray-crowned Rosy-Finch L. t. griseonucha, Adak Island, 17 May 2010.
The very dark brown breast of this griseonucha only slightly contrasts with its black throat. Compare the photos of littoralis above.
“Aleutian” Gray-crowned Rosy-Finch L. t. griseonucha, Unalaska, 10 October 2009.
If an Aleutian griseonucha were to find itself in a flock of littoralis and tephrocotis on the Homer Spit or elsewhere in Southcoastal Alaska it might be separated by its larger size, darker brown breast contrasting less with the black throat, and slightly longer more slender bill. This would be a subtle and difficult identification for sure, especially since the resident griseonucha on Kodiak appear to be intermediate in size and plumage between griseonucha farther west and littoralis. In this case an unequivocal identification to subspecies in the field may not be possible.
Sources:
- American Ornithologists’ Union. 1957. Check-list of North American Birds, 5th ed. Lord Baltimore Press, Baltimore, MD.
- Gabrielson, I. N., and Lincoln, F. C. 1959. The Birds of Alaska. Stackpole, Harrisburg, PA.
- Gibson, D. D., and Kessel, B. 1997. Inventory of the species and subspecies of Alaska birds. Western Birds 28:45-95.
