Sabine's Gull Life History

Habitat

Habitat Oceans

On their breeding grounds in the tundra, Sabine’s Gulls select low-lying wet areas with freshwater pools or lakes, as well as tidal marshes, often near coasts or on small islands. In North America and Siberia, nesting Sabine’s Gulls seldom venture into saltwater, feeding mostly in the vicinity of the nest, in sedge meadows, freshwater pools, and brackish sloughs. Inland, they nest in complex wetlands that have a mosaic of marshes, ponds, and elevated patches, among water sedge, pendant grass, creeping alkali grass, dwarf willows, mosses, and many flowering plants. After the young hatch, the adults bring them to freshwater ponds or brackish coastal ponds near the nest, where they feed on fly and midge larvae. In Greenland, Sabine’s Gulls often nest in saltwater environments, among terns on islands in fjords, for instance. After the young fledge, Sabine’s Gulls begin moving toward coastal areas, including beaches, estuaries, and mudflats, in preparation for their long migration to the wintering grounds. Migrants appear in a great range of habitats, from lakes and rivers far inland to pack ice edge in the Arctic. The largest flocks of migrants are normally off the West Coast in autumn, where they forage at areas of upwelling, often with other seabirds, along the continental shelf or continental slope. On their wintering grounds, they also use pelagic (deep) water, especially zones of upwelling along the continental slope, from the tropics into the temperate zones. Reports of the species around Greenland and northern Alaska in winter indicate that some may remain all year in the Northern Hemisphere.

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Food

Food Aquatic invertebrates

Sabine’s Gulls eat small fish, crustaceans, insects, and offal such as fishing discards. Migrants arriving to the Arctic in spring sometimes feed on snowbanks, in tidal rips, behind fishing vessels, and along leads and edges in sea ice, where they take small fish, crustaceans, and offal from boats. Once settled into breeding grounds, Sabine’s Gulls and their young feast in freshwater pools on the larvae and adults of beetles, flies, caddisflies, craneflies, midges, springtails, and mosquitoes. They walk along the edges or swim through wetlands, picking tiny insects and spiders much as a shorebird would, gleaning them from the vegetation or water. They sometimes hawk flying insects in flight, wade into shallow water to hunt prey on the bottom (flushing it by stamping or shuffling their feet), or even spin in the water, like a phalarope, to bring prey nearer the water’s surface. Occasionally they eat the eggs or nestlings of other birds or steal fish from nesting Arctic Terns. In Greenland, nesting Sabine’s Gulls often forage in saltwater, especially around strong tidal currents. Additional prey include earthworms, wasps, bristleworms (polychaetes), jellyfish, Arctic cod, threespine stickleback, ninespine stickleback, rainbow smelt, Pacific herring, chum salmon, shrimp, and many sorts of small crustaceans (amphipods, mysids, euphausiids, copepods).

After the breeding season, Sabine’s Gulls gather along shorelines, where they feed on mudflats like a plover, flip over debris like a turnstone, or swim along the water’s edge, picking at tiny prey in the sea foam, much like a Ross’s Gull. They also scavenge small marine organisms that have washed up on beaches. For the rest of the nonbreeding season, most Sabine’s Gulls are birds of the open ocean, seizing prey near the sea surface either while swimming or with a quick dip or plunge while flying. They sometimes hover delicately and patter on the water like a storm-petrel. Where prey is abundant, they often form large flocks of several hundred birds, mixing with many other species of seabird. They also gather around feeding seals and whales to eat zooplankton or scraps from their feeding activity.

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Nesting

Nest Placement

Nest Ground

Nests are set on edges of small ponds, on islands within ponds, or on marshy tundra near shore, in mossy vegetation or on gravel.

Nest Description

Nests are shallow depressions in vegetation or gravel, seldom with lining (grass, algae, twigs, or feathers on occasion). Dimensions of the nest vary, averaging about 5.4 inches across and 0.7 inches deep.

Nesting Facts

Clutch Size:1-4 eggs
Egg Description:

Slightly pointed. Rich olive-green with darker greenish-brown, irregular markings.

Condition at Hatching:

Chicks may leave nest cup at 1 day old but typically stay on the nest platform for several days. Covered in a well-camouflaged coat of down.

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Behavior

Behavior Hovering

Sabine’s Gulls often arrive back in the Arctic before snow and ice have melted, and so they may remain in flocks and forage around coastlines until the tundra thaws. Groups sometimes gather, calling and displaying, around rivermouths and beaches. Sabine’s Gulls form long-term monogamous pair bonds, and so they often return to the previous year's territory with their mate. Here, males bring females prey items one at a time, carrying whole fish in the bill (as terns do; other gull species regurgitate a paste of prey for their mate). To present the prey, males hold their bills upright, and females peck at the partner’s bill where the yellow tip meets the black bill base. A receptive female then tosses her head several times (mirrored by the male) and often rubs her head and body against the male’s breast, an invitation to mate. Both sexes build the nest, incubate the eggs, and feed and defend the young, which are able to fly short distances before their flight feathers are fully grown in, much like terns. After the young have fledged, Sabine’s Gulls move back toward ocean coasts and eventually migrate (often in tight flocks, often at night) southward toward wintering grounds.

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Conservation

Conservation Low Concern

Sabine’s Gull population trends are not known. Partners in Flight estimates a global breeding population of 340,000 and rates the species an 11 out of 20 on the Continental Concern Score, indicating a species of low conservation concern. Although they breed in remote areas far from human disturbance, their pelagic habitat during most of their life cycle makes them vulnerable to pesticide contamination and oil spills. The chief conservation concern in the case of this species is climate change, which is expected to reshape the ecology of both oceans and tundra.

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Credits

Day, Robert H., Iain J. Stenhouse and H. Grant Gilchrist. (2001). Sabine's Gull (Xema sabini), 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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