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Synthliboramphus antiquus - Ancient Murrelet

Ancient Murrelet image

Geographic range:

Alaska to southern California (along the eastern Pacific)

Key features:

The white patches on the sides of the neck of this small, slate-gray backed alcid make identification, even at a distance, easy. It is the only murrelet with a small, pale bill.

Similar species:

Synthliboramphus hypoleucus -- Xantus Murrelet

Habitat(s):

bay (rocky shore), bay (sandy shore), Continental shelf
 

Primary common name:

Ancient Murrelet

General grouping:

Seabirds and shorebirds

ITIS code:

177008
 

Geographic Range

Range Description:

The Ancient Murrelet is the most widespread and abundant murrelet, all of which are in the genus Synthliboramphus. The Ancient Murrelet is native to China, Canada, Korea, Russia, United States, Taiwan, and Mexico, with a global range of up to 1 million square kilometers. They can occur well inland, as far south as Nevada and New Mexico and as far east as Quebec and Pennsylvania. These inland observations may be associated with Pacific coast storms. They are common around the northern Pacific Rim and abundant in the eastern part. They are moderately common in the Aleutian Islands and the Gulf of Alaska, and abundant on St. Lazaria and Forrester islands. In the winter the North American breeders disperse as far south as central California.

Subtidal depth notes:

Ancient Murrelets can dive to 165 ft deep in pursuit of prey.

Habitats

bay (rocky shore), bay (sandy shore), Continental shelf

Habitat notes:

Occurs mostly at sea.

Abundance

Relative abundance:

Uncommon October-March, but irregular

Species Description

General description:

The Ancient Murrelet is a small, cold water auk that is heavier-bodied and shorter billed than other murrelets. The white patch on the sides of its neck makes identification, even at a distance, easy. Its pale bill is also diagnostic. Breeding adults have a uniform gray back, upper wing, and upper tail coverts. The head, throat, and sides to the breast are black. The rest of the underparts are white except for a sooty brown line dividing the belly from the underwing. Tail feathers are dark slate. A fringe of long, filamentous, white feathers, which form a crest at the back of the neck, rings the crown and there is a small white barred band at the side of the neck. Many are in breeding plumage by December.

The non-breeding adult is similar to the breeding plumage but lacks the black throat, chin, and sides to the upper neck, which become a sooty gray. The white filamentous plumes are greatly reduced. Juveniles and first-winter birds are similar to their parents non-breeding plumage but with a shorter, darker, and more slender bill, and little to no white trim at the crown. The pale blue legs and webbed feet are set back on the body much like a murre, thus they do not stand upright on land but lie forward on their belly. The toes, tarsus (ankle bone) and claws are black. To run on land they flap their wings to keep upright. The cream-colored to yellowish bill is short (about 2 cm), rather thick, and somewhat laterally compressed. There can be variable amounts of black along the top of the upper mandible, with the external nostrils slightly raised. Eye color is dark brown. Ancient Murrelet flight is swift, direct and low.

Distinctive features:

The Ancient Murrelet is a small, heavy-bodied auk with a uniform slate-gray back, black head, throat, and sides, and the rest is white. A distinctive and diagnostic white patch runs up the sides of the neck from the white breast during breeding. The small yellowish bill is distinctive, as other murrelets have black bills.

Size:

Length: 7.9 -9.4 in (20 -24 cm) Wingspan: 17.7 – 18.1 in (45 -46 cm) Weight: 5.4 – 8.8 oz (153 – 250 g)

Natural History

General natural history:

Ancient Murrelets spend most of their time on cold-water seas. They forage over the edge of the continental shelf, and also closer to shore, especially where tidal currents bring food up to the surface. They nest on islands or inland in dense forests with thick moss but little underbrush. Successful mating leads to two comparatively enormous eggs. They are unique among seabirds in rearing their chicks entirely at sea. They do most of their moving to and from land at twilight, which helps them avoid predators, except for the Peregrine Falcon.

In MBNMS the Ancient Murrelet is an irregular but sometimes common visitor from October to March. It is sometimes visible from shore, especially along the rocky shore of Pacific Grove.

The world population is estimated at 1-2 million birds. It is the most abundant and widespread murrelet in the genus Synthliboramphus. British Columbia has about 500,000 breeding birds, while Alaska has about 300,000 breeding birds found in about 90 colonies. Asia has several tens of thousands. It is believed that throughout their range numbers have diminished with the introduction of mammalian predators.

Predator(s):

Peregrine Falcons, rats, raccoons, and foxes.

Prey:

The Ancient Murrelet mainstay is planktonic crustaceans, especially euphausiids, and sand eels during the breeding season. Later in the season, small fishes (often juvenile shiner perch and rockfishes), krill, and shrimp are consumed. Change in diet is due to change in prey availability. They forage offshore (up to 12 miles) and dive as deep as 165 ft. Because they are only on shore during the breeding season and the chicks are fed at sea, very little detail is actually known about their diet.

Feeding behavior

Carnivore

Feeding behavior notes:

The Ancient Murrelet is agile in flight and will often plunge directly from their flight into water to forage. They swim, using their wings as flippers and catch most of their food within 60 feet of the surface, and will also sometimes head-bob for prey when sitting on the surface of the water. They forage mainly near the continental shelf or slope waters with surface temperatures from 4 to 20 C.

They seldom feed solitarily, more often in flocks of up to 30, sometimes moving in line, abreast. They are sometimes found in mixed species flocks with Black-legged Kittiwakes, Rhinoceros Auklets, and others, usually concentrating on swarms of euphausiids, where the Ancient Murrelets will be found at the perimeter of the flock. They will also feed around the bows of slow moving ships.

June - August

Reproduction:

Ancient Murrelets nest in small colonies on islands that are frequently steep or in coastal forests that may extend inland up to 300 m. In British Columbia they breed in association with Cassin’s and Rhinoceros auklets and storm-petrels. In Alsaka they associate with auklets and puffins.

They nest in colonies of 1,000 to 10, 000 pairs at the base of large trees, in burrows, under roots, or under grass tussocks. They are nocturnal, courting on the surrounding slopes, with the males singing (mostly a rhythmic series of chirrups, chips, trills, and rasps) from tree branches and other high perches. They have strong nest site fidelity and a long-term pair bond. Both sexes dig the burrows, which range from 2 to 5 feet long, ending in a nest chamber lined with twigs, leaves, and grass.

Successful mating results in two very large (2.4 in), buff with light brown to lavender marked eggs, each weighing about 25% of the female parent’s weight. Incubation by both parents lasts from 33 to 36 or more days, with extended shifts on the nest sometimes as long as 2 to 6 days, while food is sought by the absent mate. Within 2 to 4 days of hatching the downy, semiprecocial chicks are called by their parents to climb out of the burrow. The parents then fly to sea and continue to call for their chicks. The chicks run to the shore from their burrow and enter the water, and are able to immediately swim to their parents, which they identify by their voice among the throngs of other Ancient Murrelets. They swim away from shore throughout the night. They can also dive well, using both their feet and wings for propulsion. Once at sea, the chicks receive their first meal. The Ancient Murrelet is unique among seabirds in rearing its young entirely at sea. They remain together for at least a month with the parents feeding the chicks. At sea they make a vocalization like a short, whistled teep. It is thought that nocturnal behavior and rearing chicks at sea may result in the relatively low adult mortality rate. Family groups have been found 30 miles from the colony within 18 hours of departure.

July - September

Migration:

After the young Ancient Murrelets have hatched they disperse with their parents widely at sea. In winter they prefer coastal areas, and may be seen foraging in kelp. They do not have a true migration, although heavy ice in the Arctic will force the birds southward.

September - May

Feeding:

Some Ancient Murrelets remain within their breeding range throughout the year. However there is a general dispersal southward in winter as far as California, where they arrive in numbers by late October. They can be seen regularly south to San Luis Obispo County, where they prefer coastal areas, often foraging within the kelp bed. Christmas Bird Counts show highest numbers off Vancouver Island, Washington, Oregon, and northern California.

Listing Status:

The IUCN lists the Ancient Murrelet of “Least Concern”. It is protected under the Migratory Bird Convention between the U.S. and Canada. In 1993 Canada classified it as “Designated Special Concern.” The Status of the species was re-examined and confirmed as Vulnerable in 2004.

The world population is thought to be around 1 to 2 million. Although still abundant, the population has been declining for many years. They are very sensitive to disturbance when nesting/incubating and more than 20% of burrows will be deserted after any intrusion. Bright lights attract them, which may lead them to fishing boats or offshore wind farms and that presents the risk of flying into the rotor blades.

Oil contamination and loss of habitat are also potential threats. It is one of the commonest birds killed in oil spills in the Sea of Japan.

In Alaska eradication of arctic foxes and rats from some breeding island populations appears to lead to a quick recovery. Raccoons continue to be a problem even on islands where attempts have been made to eradicate them. Control of raccoons is the most urgent issue in British Columbia and probably globally.

Monitoring Trends:

Ancient Murrelet numbers have declined in recent years on breeding islands where introduced predators (e.g., rats, raccoons) have established populations. However, once introduced predators are removed, recovery can be rapid. REGEHR, H.M., RODWAY, M.S., LEMON, M.J.F. & HIPFNER, J.M. 2007. Recovery of the Ancient Murrelet Synthliboramphus antiquus colony on Langara Island, British Columbia, following eradication of invasive rats. Marine Ornithology 35: 137–144.
Ehrlich, P., D.S. Dobkin, and D. Wheye. 1988. The Birders Handbook: A Field Guide to the Natural History of North American Birds. Simon & Schuster Inc., New York. 785 p.
NOAA. 1994. Beached marine birds and mammals of the North American West Coast: a revised guide to their identification. NOAA Sanctuaries and Reserves Division, U.S. Department of Commerce
Regehr, H.M., Rodway, M.S., Lemon, M.J.F. & Hipfner, J.M. 2007. Recovery of the Ancient Murrelet Synthliboramphus antiquus colony on Langara Island, British Columbia, following eradication of invasive rats. Marine Ornithology 35: 137–144.
Roberson, D. 2002. Monterey Birds 2nd edition. Monterey Peninsula Audubon Society, Carmel, CA. 536 p.
Sibley, D.A. 2000. The Sibley Guide to Bird. Alfred A. Knopf, Inc. 545 p.
WWW
Cornell Lab of Ornithology
All About Birds
http://www.allaboutbirds.org/guide/search

WWW
eNature.com. Field Guides.
http://www.enature.com/fieldguides/eNature.com 2007

WWW
Seattle Audubon Society.
http://www.seattleaudubon.org/birdweb/

WWW
WhatBird.com. Field Guide to Birds of North America.
http://www.whatbird.com