From Opus

Revision as of 20:49, 17 August 2012

Photo by scottishdude
Clearwater Florida, March 2006

Larus delawarensis

Identification

L. 49 cm (17.5")
A fairly small white-headed gull, with gray back, thick bill, very narrow white crescents on back, a few white primary tips showing when standing, and pale yellow eye.

Juveniles have contrasting white belly, pale rump with black tail band, and black primaries.

1st summer
Photo by bobsofpa
Honeymoon Island State Park, Florida, USA, April 2008

Similar Species

• Mew Gull is slightly smaller with slightly darker back, dark eye, much thinner bill (sometimes with very thin ring), broad white crescents on back, and more white primary tips. Juveniles have uniform black-brown upperparts. Juvenile to 1st summer have brownish primaries.
  
• California Gull is larger with slightly darker back, dark eye, red and black marks on slightly longer bill. 2nd winter similar to 1st winter Ring-billed but back darker gray, dark eye, and blueish legs.
  
• Herring Gull is much larger Adult similar but with larger bill, pink legs, more extensive streaking on neck. 3rd winter similar to 1st winter Ring-billed but much larger with pink legs, and much more streaking to neck and head.

Distribution

1st winter
Photo by Urban Wildlife DFW Urban Wildlife
Dallas, Texas, February 2012

In breeding season found in Canada and the northern United States. Winters south to Mexico. Rare but regular vagrant to the UK with records annually. Accidental to France, Germany, The Netherlands, Portugal, Spain, Hungary, Italy, Sweden, Norway, Denmark, Morocco, South Africa, and Japan.

Taxonomy

This is a monotypic species^[1].

Habitat

Lakes, rivers and the coast.

Behaviour

Breeding

Photo by Screech
Island Beach State Park, New Jersey, USA, January 2011

They build their nests on the ground. They tend to return to breed at the colony where they hatched. Once they have bred, they are likely to return to the same breeding spot each year, often nesting within a few meters of the last year's nest site.

Diet

Includes insects, fish, grain, eggs, earthworms and rodents.

References

1. Clements, JF. 2010. The Clements Checklist of Birds of the World. 6th ed., with updates to December 2010. Ithaca: Cornell Univ. Press. ISBN 978-0801445019. Spreadsheet available at http://www.birds.cornell.edu/clementschecklist/Clements%206.5.xls/view

• List of references

External Links