Ancient murrelet

Ancient Murrelet
Scientific classification
Kingdom Information
Domain	Eukaryota
Kingdom	Animalia
Subkingdom	Bilateria
Branch	Deuterostomia
Phylum Information
Phylum	Chordata
Sub-phylum	Vertebrata
Infraphylum	Gnathostomata
Class Information
Superclass	Tetrapoda
Class	Aves
Sub-class	Neornithes
Infra-class	Neoaves
Order Information
Superorder	Passerimorphae
Order	Charadriiformes
Infraorder	Charadriides
Family Information
Superfamily	Laroidea
Family	Alcidae
Sub-family	Alcinae
Tribe Information
Tribe	Synthliboramphini
Genus Information
Genus	Synthliboramphus
Species Information
Species	S. antiquus
Population statistics
Population	2,000,000+ (1996 est)
Conservation status	Least concern

The ancient murrelet (Synthliboramphus antiquus) is a species of bird of the family Alcidae, and found in the coastlines and adjacent waters of the northern Pacific Ocean.

Description

The ancient murrelet is a small alcid, with a body length of 7.9-9.4 inches, a wingspan of 17.7-18.1 inches, and a body weight of 5.4-8.8 ounces. The neck is short and the body is round. The head is black with a white neck and belly, gray-black back and wings. Its summer plumage bears a pair of white to light-grey streaks on the back of the head. The English word "ancient" is an adjective of "old" in reference to this particular color, a reminder of the grey hair on the head of an old man. Non-breeding adults and juveniles do not bear these streaks. The color of the beak is light yellow, with the top and base darkened.

In flight these birds flap their short wings frequently, and often bank from side to side.

Subspecies

• Synthliboramphus antiquus antiquus; eastern Asian mainland, Aleutians and southern Alaska; winters to California
• Synthliboramphus antiquus microrhynchos; eastern Russia (Commander Islands); winters to Japan (Ryukyu Islands)

Range

The ancient murrelet is found mainly in the cold temperate zone in the northern Pacific; in Asia, however, it also extends further south to subtropical waters off the coast of China. During the winter, these birds make a striking migratory movement to the south. Among other things, they can also be observed off the coast of California. Their breeding colonies lie on islands between the 52nd and 60th north latitude in the eastern Pacific and between the 35th and 62nd northern latitude on the Asian coast. They are frequent birds within their range, and usually observed in large numbers. There are 13 breeding colonies on the Queen Charlotte Islands, each with well over 10,000 breeding birds. Prolific fliers despite their size, they have been recorded as making a transit across the main body of the Pacific Ocean, and one bird has been recorded landing on the coast of Great Britain, some 10,000 from where it normally was, and it returned twice.

During the winter months, some birds remain in their breeding area, while others go south. Off the coast of the US state of Oregon, for example, they can be seen between October and November and again in March.

Diet

Ancient murrelets seek their food in swarms of up to fifty individuals that dive more or less simultaneously. They are often associated with swarms of other species of birds, typically kittiwakes, rhinoceros auklets and other krill-eating seabirds, and are usually found on the fringes of such swarms. They attract seagulls because they bring small shoaling fish to the surface through their dives. How deep they dive is not yet known, but they have been observed to stay underwater for less than 45 seconds, suggesting a depth of 45 to 90 feet. Their main food is young sand eels and krill, herring and other species of juvenile fish of other species.

Breeding

Ancient murrelets breed in colonies, with nests dug into the earth up to 1,200 feet from the coastline. In temperate climates, the colonies are often found in forests where the alks dig their burrows up to six feet long under trees. Where there are no trees, as in the Aleutian Islands, they prefer to breed in dense vegetation and build their burrows under high tufts of grass. They also use rock crevices and cavities under boulders. In British Columbia, these colonies can be mixed with similar seabird colonies, such as rhinoceros auklets and petrels.

Nest

The actual nest is a hollow that is sparse with small twigs, leaves and dry grass. The corridors of the burrows are usually slightly curved, so that brooding birds and chicks are not visible from the entrance. In nests where the entry is too short, the breeding birds occasionally pull vegetation to conceal the entry, so that the nest hole looks unused from the outside. As a rule, ancient murrelets prefer fresh-dug burrows, so that in a breeding colony there are often many unused ones.

Egg laying and chicks

The beginning of egg laying varies depending on the respective distribution area. In China, the peak of egg laying around March 15; on the Kamchatka peninsula it usually takes place from the end of June to the beginning of July. Typically, the waters near the breeding colony at the time of egg laying have a surface temperature of between six and eleven degrees Celsius. The females usually lay two eggs, with the brooding period between 28 and 37 days. Unusual for a bird, the eggs are insensitive to brood interruptions, and offspring that have been abandoned for 24 hours still successfully hatch. Young birds are fed by their parents for up to a month, and are the only known bird species in which parental care and rearing is done entirely at sea. The success in time between egg laying and adulthood is unusually high in largely undisturbed breeding colonies. Eggs that have been incubated for at least 30 days hatch 96 percent of the young.

Threats

Predators of ancient murrelets include deer mice, which are native to many islands off British Columbia, preferring to eat eggs shortly before hatching or kill newly hatched chicks if the parent birds are not present. Ravens, eagles, seagulls, and owls, as well as foxes, raccoons, and rats, if found on the islands with breeding colonies, feed on chicks and adults as well as eggs. One of the main predators is the peregrine falcon, whose own food intake can consist of up to fifty percent of ancient murrelets when found near breeding colonies.

The population of ancient murrelets has been estimated at one to two million individual birds. As with many other alcids, ancient murrelets are threatened by the introduction of mammals on the islands where their breeding colonies are found, and the ICUN has noted a slight decline in overall numbers as a result. It is believed that this resulted in population drop in the Aleutian Islands of more than 80 percent and on the Queen Charlotte Islands by more than 50 percent; in one such colony in Canada it was discovered that this bird was reduced to 10,000 breeding pairs, from a high of 200,000, by rats alone. Also threatened are the breeding colonies off Korea, Japan and China, where the stock is generally smaller and these birds are not subject to any protective measures.