Thick-billed Murre Life History

Habitat

Habitat Oceans

Thick-billed Murres nest on rocky cliffs and headlands, mostly in the High Arctic. During the breeding season, they forage near the edge of sea ice and also in places where a combination of strong seawater currents and topography concentrates prey. When not breeding, they are true seabirds, remaining on the ocean rather than coming ashore to rest or roost. Where their range overlaps with the Common Murre, Thick-billed tends to forage over deeper waters, farther from shore, than Common. In most places, they forage over waters more than 100 feet deep, usually over the continental shelf and continental slope. Unlike Common Murres, Thick-billed sometimes winters in pack ice, where large openings provide access to prey.

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Food

Food Fish

Thick-billed Murres eat mostly small fish, along with squid, shrimp, and small crustaceans. They forage alone or in flocks, often with other seabird species. Like other auks (alcids), Thick-billed Murres capture prey with the bill during deep dives. They “fly” underwater, using their wings for propulsion and their feet for steering. Although these birds seem awkward on land, they are agile, swift, even graceful when pursuing fish underwater. They dives as deep as 689 feet although most prey is taken at depths of around 60 feet. They usually consume their prey while still underwater. A typical dive starts with a rapid descent, then foraging at or near the sea floor, and a rapid ascent back to the surface. Prey include walleye pollock, Arctic cod, Atlantic cod, Atka mackerel, capelin, Pacific herring, daubed shanny, and various species of sandlance, sculpin, blenny, lumpsucker, lanternfish, shrimp, annelid (segmented) worm, and crustaceans (amphipods, decapods, mysids, euphausiids).

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Nesting

Nest Placement

Nest Cliff

Thick-billed Murres lay their single egg directly on a cliff ledge or similar site (sometimes a crevice or cave) at the edge of the ocean.

Nest Description

No nest is constructed, but adults sometimes arrange small pebbles around the site where the egg is laid, and these become cemented by guano (excrement), which perhaps helps the egg to stay on the cliff.

Nesting Facts

Egg Description:

Very pointed at one end. Color variable, ranging from white to tan without markings, to dark green or turquoise with extensive black spots and scrawls.

Condition at Hatching:

Covered in down, able to stand within one day.

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Behavior

Behavior Surface Dive

Thick-billed Murres nest in large colonies on cliffs overlooking saltwater, mostly in the High Arctic, often among Black-legged Kittiwakes, Common Murres, Razorbills, and Northern Fulmars. They perform little in the way of courtship other than perhaps to chase each other across the sea surface, wings flapping, or mutual preening. When descending from a nesting ledge, some use an exaggerated form of flight with slow wingbeats. Male and female often arrive already paired at breeding colonies, and may stay paired for many years. Younger murres (in their first or second nesting seasons) often switch partners between seasons. Although Thick-billed Murres do defend their nest sites against others of their species, conflict is usually brief. They nest very close together in most colonies, even touching their neighbors as they incubate. Both sexes share incubation and chick-feeding duties, with one parent present as the other forages at sea or rests on the sea below the nest ledge. When feeding young, they may travel over 100 miles on foraging flights, usually traveling in groups with a distinct leader, and usually traveling on a direct course to and from the foraging area. Young birds plunge over the nest ledge before they are able to fly, and the male parent guides them to sea and feeds them until they are independent. Females often remain in the colony for several weeks thereafter. Thick-billed Murres usually do not breed until their fourth year of life. Yearlings do not return to nest cliffs, but 2- and 3-year-old birds often return as adults are incubating. During the nonbreeding season, at sea, Thick-billed Murres generally forage on their own, but they gather in flocks where prey is abundant and sometimes congregate on floating ice when not foraging.

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Conservation

Conservation Low Concern

Thick-billed Murres are still numerous but face many conservation challenges. Partners in Flight estimates a global breeding population of 15 million birds and rates the species a 10 out of 20 on the Continental Concern Score, indicating a species of low concern. Among the chief causes of population loss are hunting and egging (particularly in Newfoundland and Labrador, Canada, and Greenland). Other threats include oil spills, heavy metal and pesticide poisoning, and entanglement in fishing gear. The impacts of climate change on ocean conditions and prey resources are likely to cause major changes to their Arctic and marine habitats.

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Credits

Gaston, Anthony J. and J. Mark Hipfner. (2000). Thick-billed Murre (Uria lomvia), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Kushlan, J. A., M. J. Steinkamp, K. C. Parsons, J. Capp, M. A. Cruz, M. Coulter, I. Davidson, L. Dickson, N. Edelson, R. Elliott, R. M. Erwin, S. Hatch, S. Kress, R. Milko, S. Miller, K. Mills, R. Paul, R. Phillips, J. E. Saliva, W. Sydeman, J. Trapp, J. Wheeler and K. Wohl (2002). Waterbird conservation for the Americas: The North American waterbird conservation plan, version 1. Washington, DC, USA.

Lutmerding, J. A. and A. S. Love. (2019). Longevity records of North American birds. Version 1019 Patuxent Wildlife Research Center, Bird Banding Laboratory 2019.

Partners in Flight (2017). Avian Conservation Assessment Database. 2017.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.

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