WatchList Species Account for Ancient Murrelet (Synthliboramphus antiquus) |
Qualifies for the list as a Declining Yellow List Species
|Photo: Ashok Khosla
This colonial-nesting alcid is a member of a genus that rears its young entirely at sea. The parents come to their nest burrow at night, where they incubate their eggs in shifts as long as 2-6 days. When the chicks hatch, the parents do not feed them in the burrow, so the young birds are forced to leave the nest after 1-3 days. The parents and chicks reunite at sea through mutual recognition of calls; the parents then feed the chicks until they are full grown, at least a month after leaving the colony.
Ancient Murrelets nest in colonies of between 1,000-10,000 pairs, smaller than those of other alcids. They breed on islands in the Aleutians and southeastern Alaska and on coastal islands of British Columbia; they also breed on a few islands off Korea, Japan, and eastern Russia. The birds spend the winter in continental shelf waters within their breeding range, and also south to central California, sometimes in large flocks, as well as in the offshore waters of Japan and Korea and as far south as Taiwan.
The bird feeds on small fishes and larger zooplankton. Birds at colony sites suffer heavy predation by Common Ravens and Bald Eagles, and, in some colonies, by rats and raccoons. The murrelet is also a main prey item for the Peregrine Falcon, forming up to 50% of the falcon’s diet during the breeding season.
The total population of the Ancient Murrelet is estimated at 1-2 million. Its numbers have been severely diminished by introduced mammals on colony islands, reducing colony sizes to about 10% of former populations. Colonies in the Aleutians are present only on islands where foxes do not exist. Oil spills have killed many murrelets, especially in the Sea of Japan.
At present there are efforts to remove foxes and rats from islands in British Columbia and Alaska; with the mammalian predators gone, murrelet numbers recover quickly.