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COSEWIC Assessment and Update Status Report on the Ancient Murrelet in Canada

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COSEWIC
Executive Summary

Ancient Murrelet
Synthliboramphus Antiquus

Species Information

The Ancient Murrelet, Synthliboramphus antiquus, is a seabird in the Alcidae, or auk family. It is most closely related to the Japanese Murrelet, S. wumizusume, but also to two other birds in North America: Xantus’s Murrelet, S. hypoleucus and Craveri’s Murrelet, S. craveri. Ancient Murrelets are about 25 cm long and are grey-bodied with a white throat and cheek, black chin and crown, and a yellow-tipped bill. In breeding plumage they have a distinctive line of white feathers extending back from the eye and fine black-and-white lines on the sides of the nape.

 

Distribution

The Ancient Murrelet breeds from the Sea of Japan to the Queen Charlotte Islands of British Columbia. There are potentially still birds in China, Korea and Japan, but their numbers are unknown, as the colonies are not surveyed on a regular basis. There are two large colonies in the northern Sea of Okhotsk in Russia. In Alaska, Ancient Murrelets breed on the Aleutian chain, the Alaskan Peninsula and the Gulf of Alaska. In Canada, they breed exclusively on small islands in the Queen Charlotte Archipelago.

 

Habitat

Ancient Murrelets breed on islands in areas that are at least 300 to 400 m from shore. They prefer to nest in forested areas, but will use treeless islands if forested ones are not available. They dig their burrows wherever there is sufficient soil depth, generally near trees or other objects for protection.

 

Biology

The Ancient Murrelet is a diving seabird that eats zooplankton and fish. They breed at 3 or 4 years of age, laying 2 eggs in April at a colonial breeding site. Chicks leave the nest with their parents when they are a few days old without ever having been fed. They spend the next month at sea, where their parents feed them until they are full-grown. Birds spend most of the year away from the Queen Charlotte Islands. They do not always return to the same colony where they were born.

 

Population Sizes and Trends

There are an estimated 256 000 pairs (about half the world population) of Ancient Murrelets nesting on 31 colonies in the Queen Charlotte Islands. Only eleven colonies have been surveyed between 1993 and 2004: Reef, Frederick and George showed an increase in number of birds, Lihou and Saunders appear stable, while the numbers on Limestone, Helgesen and Kunghit have decreased, with the population on Kunghit now believed to be extirpated. Populations on Langara and Rankine showed no statistical trend, with Langara showing no signs of recovery after rat extermination. Populations on predator-free islands are increasing by 0.2 – 9.5% annually; populations on islands with introduced mammalian predators are decreasing dramatically (up to 23% annually). Overall, the total population is likely decreasing; data from colonies with censuses in both the 1980s and 1990s show an approximate 18% decline between those decades.

 

Limiting Factors and Threats

The main factor threatening Ancient Murrelet populations around the world is introduced mammals: rats in Asia, foxes in Alaska, and rats and raccoons in British Columbia. Other risks to the Ancient Murrelet include disturbance, oil exploration, oceanographic changes and commercial fisheries.

 

Special Significance of the Species

The Queen Charlotte Islands are home to 50% of the world’s population of Ancient Murrelets. The Ancient Murrelet is the most numerous member of its genus. Its closest relative, the Japanese Murrelet, is severely endangered.

 

Existing Protection or Other Status Designations

The Ancient Murrelet, including its eggs and nest, is protected in Canada under the Migratory Birds Convention Act (1994), the Canada National Marine Conservation Areas Act(2002) and the BC Wildlife Act. Globally it is considered secure. In the United States, it has a National Heritage Status rank of ‘apparently secure’. In Canada, the Ancient Murrelet is Blue-listed (of special concern) by the British Columbia government and designated a species of Special Concern by COSEWIC.