From Opus

Alternative name: Band-tailed Gull

Photo by Alastair Rae
Arica, Chile

Larus belcheri

[edit] Identification

Adult breeding

• White head, neck, breast, sides and belly
• Sooty black mantle and wings; in flight shows white tips to secondaries
• Broad black subterminal band on white tail
• White uppertail coverts
• Long bright yellow bill tipped red (different field guides differ in whether black is found proximally of the red in adult or only in subadult)
• Long bright yellow legs and feet
• Eye is dark in all ages

Juvenile
Photo by BirdsPeru
Costa Verde, Lima, Peru, November 2004

Adult non-breeding

• Head shows a blackish hood, neck is pale grey, and bill is yellow with red tip and black subterminally
  

Younger birds

• All ages have darker head than neck (except third summer, which is very similar to adult summer but with sub-terminal black ring on bill). Mostly brown and grey with darker band on tail. Three to four years before full breeding plumage.

[edit] Similar species

Adult breeding and subadult summer are similar to Kelp Gull which has heavier bill (less bright yellow) with yellow at the very tip (red in Belcher's Gull) and overall a larger, chunkier species. Dolphin Gull is unlikely to overlap in range, and adult/subadult birds have red bill and legs while lacking black tail band, but overall similar pattern of hood in winter lacking in summer.

Photo by BirdsPeru
Lima, Peru, December 2005

[edit] Distribution

Humboldt Current of Peru and northern Chile; disperses to more southern areas in Chile and northwards to Ecuador and less commonly Colombia.

vagrant to Panama, most often in el nino years.

[edit] Taxonomy

Monotypic^[1]
Olrog's Gull, the Atlantic counterpart of this species, has in the past been considered a subspecies of Belcher's Gull.

[edit] Habitat

Coasts.

[edit] Behaviour

Middle bird in second alternate plumage, the other two less than two years old Photo by Njlarsen Llute River, Arica, Chile

Bird in second alternate plumage (same as middle bird in previous picture). Notice black middle coverts on otherwise brown wing, all black in adult Photo by Njlarsen Llute River, Arica, Chile

Bird in second basic plumage (about ½ year younger than middle bird in first picture). Photo by Njlarsen Llute River, Arica, Chile

[edit] Diet

They eat fish, crabs and other shellfish, and will also scavenge for carrion.

[edit] References

1. Clements, JF. 2008. The Clements Checklist of Birds of the World. 6th ed., with updates to December 2008. Ithaca: Cornell Univ. Press. ISBN 978-0801445019. Spreadsheet available at http://www.birds.cornell.edu/clementschecklist.
2. Avibase
3. Restall et al. 2006. Birds of Northern South America. Yale University Press. ISBN 9780300124156
4. Alvaro Jaramillo. 2003. Birds of Chile. Princeton Field Guides. ISBN 0-691-11740-3
5. Ridgely & Gwynne 1989. Birds of Panama. Princeton Paperbacks. ISBN 0691025126
6. Arthur Grosset

• List of references

[edit] External Links

• Arthur Grosset's Birds