Compiler*: Debra G. Corbett | Nanutset Heritage
(All photos courtesy of the USFWS. *Originally presented in “From the Wildside” USFWS /Alaska Maritime National Wildlife Refuge / Aleutian Islands Unit Newsletter)
Kittlitz’s and Marbled murrelets are among the least-studied seabirds in North America. Both live and breed in the Aleutian Islands and are found primarily around mountainous islands with deep bays. Both species spend the majority of their lives at sea and come ashore only to breed. Unlike most other alcids they do not nest in large colonies, instead they establish isolated nest sites at high elevations. Also unlike other alcids their breeding plumage is cryptic, light colored and mottled which serves to disguise the nesting birds. In winter they sport more dramatic white and dark plumage.
Kittlitz’s murrelets are small, stocky birds with a relatively large head and short bill and tail. Both female and male birds have a light, off-white underside, with brown, gray, and reddish-gold feathers on the back, wings, and head. In winter they have a white underside, throat, and face, with black or dark gray back, wings, cap, and sometimes a distinct black necklace. They forage in turbid nearshore waters for small fish, especially Pacific sandlance, Pacific herring, capelin, and Pacific sandfish, and shrimp-like crustaceans called euphasiids, and amphipods.
All of the North American, and most of the world population of Kittlitz’s Murrelets, breed and winter in Alaska. Total population numbers are unknown but 4,000 birds have been counted in the Aleutians with major concentrations off Unalaska (1500 birds) and Adak (1000 birds). Pairs establish a remote nest site on steep unvegetated mountainsides, or slopes above the timberline near glaciers and cirques. Biologists think they are monogamous and lay one egg in June that hatches in July. The young fledge in August. To get from the nesting site to the sea, up to 40 km away, the fledglings may float down small streams.
As late as 2000 only 17 nests had ever been found. In 2006 a biologist stumbled upon a nest on Kodiak and since about 2010 biologists Robb Kaler and Leah Kenney have been hunting nests on Adak. In 2012 they found nine nests in the mountains of Adak. Their search continues with new nests found each year since.
Marbled murrelets are small, chunky birds with pointed wings and a slender black bill. Non-breeding plumage is white underneath with a black crown, nape, wings, and back. When breeding, both sexes have a brown mottled body and face. They feed primarily on fish and invertebrates in near-shore marine waters, protected bays, and even on rivers and inland lakes. Their main prey include sandeels, herring, capelin and shiner perch, along with euphasiids and amphipods. Marbled murrelets often forage in pairs. Loose aggregations of 500 or more birds occasionally occur in winter.
The total population exceeds 20,000 with about 10,000 in the Aleutian Islands, where 7,000 live and breed around Unalaska. The most common nesting sites for marbled murrelets are on branches of old-growth and mature conifers, as far as 80 km inland. Before 1990 only four marbled murrelet nests had ever been seen. In the non-forested portions of Alaska however, they nest on the ground in a small depression. No marbled murrelet nests have been found in the Aleutian Islands, but recently fledged birds have been seen. Marbled murrelets produce one egg per nest. Incubation by both parents lasts a month then the chick is fed for around 40 days until it is able to fly. It then leaves the nest and flies unaccompanied to the sea. Breeding success is low and chick mortality high.
For more information: Gibson, Daniel D., and G. Vernon Byrd. 2007. Birds of the Aleutian Islands, Alaska. Nuttall Ornithological Club and The American Ornithologists’ Union. AOU Publications Office, Fayetteville, Arkansas