Species Profile
Black-tailed Gull
Larus crassirostris
Quick Facts
Conservation
LCLeast ConcernLength
43–51 cm
Weight
436–650 g
Wingspan
126–128 cm
Migration
Partial migrant
Also known as: Japanese Gull
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Appearance
The Black-tailed Gull is a medium-sized seabird with a distinctive appearance. It has a white head and body, contrasting with slate-grey wings and back. The wingtips are black with small white tips, and a broad black band across the tail gives this species its name.
Adults have yellow legs, a yellow bill with a red spot near the tip, and a black ring. In winter, the white head shows some dark mottling, especially at the back of the neck. Juveniles are predominantly dark brown with lighter edges to their feathers and take about three years to develop adult plumage.
Identification & Characteristics
Colors
- Primary
- White
- Secondary
- Black
- Beak
- Yellow
- Legs
- Yellow
Attributes
Understanding Attributes
Rated 0–100 based on research and observation. A score of 50 is average across all bird species. These attributes are relative and don't necessarily indicate superiority.
Habitat & Distribution
Black-tailed Gulls are primarily found along the coasts of East Asia, including Japan, Korea, and eastern Russia. They inhabit rocky coastlines, offshore islands, and occasionally inland lakes. During the breeding season, they form large colonies on coastal cliffs and flat, rocky areas.
In winter, some populations migrate southward to warmer regions, reaching as far as Southeast Asia. Vagrant individuals have been spotted in North America, particularly along the western coast of the United States and Canada.
Distribution
Diet
Black-tailed Gulls have a varied diet, primarily consisting of fish, squid, and crustaceans. They are opportunistic feeders, also consuming insects, small mammals, and eggs of other seabirds.
These gulls are known to forage in intertidal zones during low tide and often scavenge human food waste in urban areas.
Behaviour
Black-tailed Gulls are highly social birds, often seen in large flocks along coastlines. They are skilled flyers, capable of soaring on air currents and diving into water to catch fish.
These gulls are known for their opportunistic feeding behaviour, often following fishing boats to scavenge discarded fish.
Calls & Sounds
Black-tailed Gulls have a range of vocalisations, including a loud, harsh 'kow-kow-kow' call often heard in breeding colonies.
They also produce a softer, mewing sound during courtship and when communicating with their chicks. In flight, they may emit a sharp, high-pitched 'kee-aw' call.
Nesting & Breeding
Black-tailed Gulls typically breed in large, noisy colonies from April to July. Pairs engage in elaborate courtship displays, including head-tossing and mew-calling, to strengthen their bond. They nest on flat, rocky areas or cliff ledges near the sea.
The nest is a shallow scrape lined with vegetation, feathers, and debris. Females usually lay 2-3 eggs, which are olive-brown with dark spots. Both parents take turns incubating the eggs for about 24 to 26 days.
Chicks are semi-precocial, able to walk soon after hatching but remain in the nest area. They fledge after 35-40 days but continue to be fed by their parents for several more weeks.
Conservation
While the Black-tailed Gull is currently listed as Least Concern by the IUCN, it faces threats from habitat loss due to coastal development and pollution. Climate change and rising sea levels may also impact their breeding sites in the future.
Conservation efforts focus on protecting coastal habitats and reducing marine pollution.
Elevation
Sea level to 100 meters
Additional Details
- Predators:
- Main predators of Black-tailed Gulls include large raptors such as eagles and falcons, as well as mammals like foxes and rats that may prey on eggs and chicks.
Birdwatching Tips
- Look for Black-tailed Gulls along rocky coastlines and in harbours
- Observe their distinctive black tail band in flight
- Listen for their loud, harsh calls, especially in breeding colonies
- Watch for their scavenging behaviour near fishing boats
Did You Know?
- Black-tailed Gulls can drink both fresh and salt water, thanks to special glands that remove excess salt from their bloodstream.
- They have been observed using 'tool-like' behaviour, dropping shellfish onto rocks to break them open.
- In Japan, these gulls are considered a symbol of the seaside and often feature in coastal town emblems.
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