Sabine's Gull
The Sabine's Gull (Xema sabini) is a small, distinctive, Arctic-breeding seabird known for its unique tricolored wing pattern and long-distance migratory behaviour, wintering in productive ocean waters in the Southern Hemisphere. It is the only species in the genus Xema.
Identification:
Distribution and Habitat:
Diet and Behaviour:
Identification:
- The most notable feature of the Sabine's gull in all plumages is its striking, geometric upperwing pattern, which forms alternating triangles of black (outer primaries), white (inner primaries and secondaries), and grey (back and wing coverts).
- Breeding Adult: Has a dark grey (charcoal) hood that is bordered by a narrow black collar, a black bill with a yellow tip, and a slightly forked white tail.
- Non-breeding Adult: The dark hood is replaced by a smudgy grey partial hood or dusky patches on the nape and sides of the neck; the rest of the head is white. The bill retains the black with a yellow tip, and the tail is all white.
- Juvenile: Features a brownish-grey, scaly-patterned back and neck. They have the same general wing pattern as adults, but the grey areas are replaced with brown, and the tail has a broad black terminal band. Juveniles have an all-black bill.
Distribution and Habitat:
- Breeding Grounds: The Sabine's gull breeds in colonies on marshy coastal tundra wetlands in the high Arctic regions of North America and Eurasia (including Greenland and Svalbard). They prefer areas with numerous freshwater pools and lakes for foraging.
- Wintering Grounds: Outside of the breeding season, the species is pelagic, meaning it lives on the open ocean. The populations from the East Atlantic winter in the cold waters off the south-west coast of Africa (Benguela Current), while most from western North America and Siberia winter in the southeast Pacific Ocean (Humboldt Current).
- Migration: It is a long-distance migrant, often seen as a scarce passage migrant along western coasts of Europe and North America during the autumn, particularly following strong south-westerly gales.
Diet and Behaviour:
- Diet: The gull is an opportunistic feeder. During the breeding season, its diet mainly consists of terrestrial and aquatic insects and their larvae (such as beetles, craneflies, and mosquitoes), small crustaceans, and sometimes the eggs or young of other birds. In winter and during migration, they primarily eat marine invertebrates and small fish from the ocean's surface, often in areas of cold water upwelling.
- Behaviour: They forage using various methods, including surface-seizing prey while flying or swimming, marching in shallow water to flush out food, or occasionally "hawking" insects in the air. They are often social during migration and winter, forming flocks, but usually nest in smaller colonies (around 6-15 pairs) or sometimes singly, often among Arctic terns for protection from predators.