Birding Alaska

Often when a species has an obvious and diagnostic field mark the tendency is to quickly identify the bird, ignore its other marks, and move on.  Identifying a Red-legged Kittiwake is easy if you see the field mark for which the bird is named, and if you travel to the Pribilof Islands during the breeding season you’ll have that opportunity.  However, on a flying bird or a bird seen at sea the red legs are difficult to see, so to pick out an out of range Red-legged Kittiwake you’ll need to focus on other identifying marks.  Once learned, these marks help to make the identification of a flying Red-legged Kittiwake straight forward even at a distance.

Red-legged Kittiwake and the similar and more widespread Black-legged Kittiwake are the only gulls in the genus Rissa. Both are small, cliff-nesting gulls that spend the non-breeding season primarily at sea.  Unlike the Black-legged Kittiwake which is circumpolar in distribution the Red-legged is endemic to the Bering Sea region, nesting at the Pribilof Islands and a few islands in the Aleutians, most notably Bogoslof and Buldir Island.  The species also breeds at the Commander Islands, in the waters of the Russian Bering Sea (Gibson and Byrd 2007).  Red-legged Kittiwake is rarely seen at sea away from its colonies and its winter distribution is poorly studied.  There are records of Red-legged Kittiwake for the Gulf of Alaska (Iseib and Kessel 1973) and even as far south as southern California (Cambell et al. 2008).

Red-legged Kittiwake Rissa brevirostris, St. Paul Island, Pribilofs, 5 July 2006.

Black-legged Kittiwake Rissa trydactyla, Eastern Bering Sea, 25 July 2009.

On the above pictures you can see that Red-legged Kittiwake is smaller, more compact, and slightly shorter legged than Black-legged.  On this bird note the short bill–for which it’s named brevirostris–and the large, round eye.  This imparts a gentle dove-like and “cute” expression that is lacking on the longer-billed Black-legged Kittiwake.

Red-legged Kittiwake (top) and Black-legged Kittiwake (bottom) in flight, Bering Sea, 4 October 2009.

These next two photos show the upperwing of both species in flight.  On the Red-legged Kittiwake the upperwing is uniformly slaty gray.  On the Black-legged Kittiwake the upperwing is light gray, especially on the outer wing, or “hand”, which is paler gray than the inner wing.  Even at a distance this two-toned appearance to the wing is evident.  Because of the paler wing on the Black-legged Kittiwake, the white trailing edge to the secondaries contrasts less with the upperwing coverts and there is no striking trailing edge to the primaries.  On the Red-legged Kittiwake upperwing note the strong contrast between the trailing edge and the upperwing coverts.  This contrast is evident on both the secondaries and the primaries.  Red-legged Kittiwake also appears more compact in flight with smoother wingbeats.  The small bill and large eye of the Red-legged Kittiwake are also evident in these flight shots.

Red-legged Kittiwake (top) and Black-legged Kittiwake (bottom) in flight, Bering Sea, 4 October 2009.

The underwing pattern of the two species differs as well.  On the Black-legged the underwing is gleaming white.  On the Red-legged the underwing is grayish on the innerwing and darker gray on the outerwing.  This makes for much less contrast between the primary tips and the rest of the primaries on the underwing of the Red-legged Kittiwake.

Red-legged Kittiwake, Bering Sea, 4 October 2009.

This shot shows all the features of the Red-legged Kittiwake: uniform slaty upperwing with contrasting white trailing edge; grayish underwing; the small billed, large-eyed, “cute” face; and the red legs (barely visible underwater). See Howell and Dunn (2007) for more information and photos of Red-legged and Black-legged Kittiwakes.

• Cambell, W. R., Sealy, S. G., Wahl, T. R., and Walker, R. P. 2008. Status of Red-legged Kittiwake (Rissa Brevirostris) in British Columbia with notes on its occurrence in Canada and the Continental United States. Wildlife Afield 5: 3-11.
• Gibson, D. D., and Byrd, G. V. 2007. Birds of the Aleutian Islands, Alaska. Nuttall Ornithological Club and the American Ornithologists’ Union. Series in Ornithology 1.
• Howell, Steven N.G., and Dunn, J. 2007. Gulls of the Americas. Houghton Mifflin.
• Isleib, M. E., and Kessel, B. 1973. Birds of the North Gulf Coast-Prince William Sound region, Alaska. Biol. Papers Univ. Alaska 14.