Kittlitz's murrelet
| Kittlitz's murrelet | |
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| B. brevirostris | |
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| Species: | B. brevirostris
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| Binomial name | |
| Brachyramphus brevirostris (Vigors, 1829)
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The Kittlitz's murrelet, (Brachyramphus brevirostris) is a small alcid found in the waters off Alaska and Eastern Siberia. This critically endangered species is, like the closely related marbled murrelet, unusual for seabirds in not being colonial, nesting instead in isolated locations on mountain tops, where the nests were known to Native Americans for many years before skeptical ornithologists described and photographed them. It is a poorly known and little studied species, although concern over its status and that of the closely related marbled murrelet has led to a recent increase in research.
The common name of this species commemorates the German zoologist Heinrich von Kittlitz, who first collected this species.
Description and range
The Kittlitz's murrelet is, like the marbled murrelet, a small compact auk, 25 cm long with tiny legs and cryptic plumage during the breeding season. The colour of the breeding plumage, greyish-brown, reflects its habit of breeding on bare ground near snowfields. In the winter it adopts the black and white plumage typical of many seabirds. Its bill is smaller than that of the marbled murrelet.
The Kittlitz's murrelet mostly breeds and lives in the coastal areas of Alaska, both on the mainland around Prince William Sound, the Kenai Peninsula, sparsely up the west coast and along the Aleutian Islands. It also nests in Siberia and possibly Wrangel Island.
Behaviour
The Kittlitz's murrelet feeds close to the shore, in particular in the waters around tidewater glaciers. It feeds on larval fish, krill and other small zooplankton. Chicks are fed with slightly larger fish carried in the bill.
The Kittlitz's murrelet is one of the least known auks, although it is known not to be colonial, nesting instead above the tree line on mountains inland from the sea. The nests are situated on south facing slopes on bare ground, often close to snow. A single egg is laid (and incubated for an unknown amount of time). Chicks are fed throughout the day, and reach fledging weight in around 25 days. The exposed nature of the nesting grounds mean that chicks keep their downy feathers later than most other birds, losing the down 12 hours before they fledge. It is assumed that they fly to sea on fledging, but it has also been suggested that they reach the seas through rivers. After the chick fledges it is thought to receive no further parental care, no chick has ever been seen with an adult at sea.
Threats
The Kittlitz's murrelet is considered to be critically endangered by the World Conservation Union, based on dramatic declines at every site studies, although it is not listed under the Endangered Species Act (it was a Species of Conservation Concern until that category was abolished). It is threatened by habitat loss from global warming (as it is seemingly dependent on retreating glaciers), disturbance by boats and oil spills. An estimated 5-10% of the world population was killed during the Exxon Valdez oil spill.[2] In much of Alaska surveys indicate that the population may have declined by 80–90% in 15 years since the early 1990s. In Prince William Sound the population declined by 84% from a population of 6436 birds in 1989 to 1033 birds in 2000, following a possible longer-term decline in 1972 when the population was estimated at 63000 birds. The rate of decline in Prince William Sound was estimated at 63% between 1989 and 2004 (5% per year). In the Malaspina Forelands the population declined by 38–75% between 1992 and 2002. Total abundance in Icy Bay, Alaska was estimated at 1725–2372 birds in 2002, suggesting a decline of 59% over a three-year period. In Glacier Bay, density estimates declined by 89.1% in 1991–2000, with 2200 estimated there in 1999–2000 and recent data suggesting that an 85–90% decline happened there between 1991 and 2008 with annual decline rates estimated at between -10.7% and -14.4%.[citation needed] In the Lower Cook Inlet, the population declined by 84% (26% per year) between 1993 and 1999. An analysis of data from the Kenai Fjords estimated that a decline of 90% has happened between 1989 and 2002, but this hampered by changing survey methods overtime, few years of survey efforts and low population numbers. The population in Alaska is estimated at 19578 birds. Data from Russia is scarce, but 5100 birds are estimated to occur along the Kamchatka and the Chukotka Peninsula.[citation needed]
External links
References
- Gaston, Anthony; Jones, Ian (1998). The Auks, Alcidae. Oxford University Press, ISBN 0-19-854032-9
- Day, R. H., D. J. Kuletz, and D. A. Nigro. 1999. Kittlitz’s Murrelet (Brachyramphus brevirostris). In The Birds of North America, No. 435 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.