The California gull (Larus californicus) is a medium-sized gull, smaller on average than the herring gull, but larger on average than the ring-billed gull (though it may overlap in size with both). It lives not just in California, but up and down the entire Western coast of North America, and has breeding ground inland.
| California gull | |
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| California gull at Palo Alto Duck Pond,[1] Baylands Nature Preserve, Palo Alto, California | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Charadriiformes |
| Family: | Laridae |
| Genus: | Larus |
| Species: | L. californicus
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| Binomial name | |
| Larus californicus Lawrence, 1854
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| Subspecies | |
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| Range of the California gull Breeding Migration Year-round Nonbreeding
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Description
editAdults are similar in appearance to the herring gull, but with brown eyes, yellow legs, and a more rounded head. The body is mainly white with grey back and upper wings. The bill is yellow with a black ring and red spot near the tip. They have black primaries with white tips. Immature birds are also similar in appearance to immature herring gulls, with browner plumage than immature ring-billed gulls. Length can range from 46 to 55 cm (18 to 22 in), the wingspan 122–137 cm (48–54 in)[citation needed] and body mass can vary from 430 to 1,045 g (0.948 to 2.304 lb).[4]
Distribution and habitat
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Their breeding habitat is lakes and marshes in interior western North America from the Northwest Territories, Canada south to eastern California and Colorado.[5] They nest in colonies, sometimes with other birds. The nest is a shallow depression on the ground lined with vegetation and feathers. The female usually lays 2 or 3 eggs. Both parents take turns feeding their chicks.
They are migratory, with most moving to the Pacific coast in winter. It is only then that this bird is regularly found in western California.[5]
Behavior
editThese birds forage in flight or pick up objects while swimming, walking or wading. They mainly eat insects, fish and the eggs and young of other birds, especially ducklings.[6] Opportunistic feeders, they also scavenge at garbage dumps, marinas and docks. They frequently beg for food at public beaches, parks and other locations where people will hand feed them. They have been known to steal food directly from people at picnics and outdoor restaurants. They may follow fishing boats or plows in fields for insects stirred up by this activity.
California gulls are also known to eat various vegetables and fruits, particularly cherries.[6] As a result, in some areas it may be regarded as a crop pest.[7]
State bird
editThis is the state bird of Utah,[8] remembered for assisting Mormon settlers in dealing with a plague of Mormon crickets.[9] A monument in Salt Lake City commemorates this event, known as the "Miracle of the Gulls".[9]
Subspecies
editThere are two subspecies recognized, the nominate from the Great Basin to central Montana and Wyoming, and the slightly larger, paler L. c. albertaensis with a more northerly distribution, ranging from Great Slave Lake onto the Great Plains of western Manitoba and South Dakota.[10] Although these subspecies are not well distinguishable by mtDNA allozyme variation,[11] they breed true and the low genetic divergence can be explained by separation during the Pleistocene and renewed contact in Montana during more recent times.[12]Removed
Status in California
editIn California, the California gull at one time held the protected status California Species of Special Concern due to declining numbers at their historic California breeding colony at Mono Lake. However, in recent decades this species has begun to breed in the southern portion of San Francisco Bay, where it did not historically breed, and has undergone exponential population growth. These California gulls now inhabit large, remote salt-production ponds and levees and have a very large food source provided by nearby landfills from San Francisco, San Jose and other urban areas, all the way up into the Sacramento area. The South Bay California gull population has grown from less than 1,000 breeding birds in 1982 to over 33,000 in 2006. This population boom has resulted in large resident flocks of gulls that will opportunistically prey on other species, particularly the eggs and nestlings of other birds. Seriously threatened birds that share the same South Bay habitat include the snowy plover and California least tern, while less-threatened birds, including black-necked stilts, American avocets, Forster's terns, and Caspian terns, are also preyed upon by the abnormally large flocks of California gulls. Efforts are underway to reduce habitat for this species and find other ways to disperse the large numbers of gulls.[13]
References
edit- ^ "Duck Pond, Palo Alto Yacht Harbor". Palo Alto Historical Association. Retrieved 10 March 2022.
- ^ BirdLife International (2018). "Larus californicus". IUCN Red List of Threatened Species. 2018: e.T22694321A132542511. doi:10.2305/IUCN.UK.2018-2.RLTS.T22694321A132542511.en. Retrieved 14 November 2021.
- ^ "Gulls (Laridae)". The World Birds. Retrieved 10 March 2022.
- ^ CRC Handbook of Avian Body Masses by John B. Dunning Jr. (Editor). CRC Press (1992), ISBN 978-0-8493-4258-5.
- ^ a b Sibley, David Allen (2000): The Sibley Guide to Birds. Alfred A. Knopf, New York. ISBN 0-679-45122-6
- ^ a b Greenhalgh, Clifton M. (1952). "Food Habits of the California Gull in Utah". The Condor. 54 (5): 302–308 – via JSTOR.
- ^ "Larus californicus California gull". Animal Diversity Web. Retrieved 13 October 2021.
- ^ "Utah State Bird". Utah.gov. Archived from the original on 2020-01-22. Retrieved 11 August 2014.
- ^ a b Ryser, Fred A. (1985). Birds of the Great Basin. Reno, NV, USA: University of Nevada Press. p. 203. ISBN 0-87417-080-X. Retrieved 11 August 2014.[permanent dead link]
- ^ Jehl, Joseph R. Jr. (1987). "Geographic variation and evolution in the California Gull (Larus californicus)" (PDF). Auk. 104 (3): 421–428. doi:10.2307/4087540. JSTOR 4087540.
- ^ Karl, S. A.; Zink, R. M.; Jehl, Joseph R. Jr. (1987). "Allozyme analysis of the California Gull (Larus californicus)" (PDF). Auk. 104 (4): 767–769. doi:10.1093/auk/104.4.767. JSTOR 4087291.
- ^ Jehl, Joseph R. Jr.; Francine, J; Bond, S. I. (1990). "Growth patterns of two races of California Gulls raised in a common environment" (PDF). Condor. 92 (3): 732–738. doi:10.2307/1368692. JSTOR 1368692.
- ^ Ackerman, J. T., J. Y. Takekawa, C. Strong, N. Athearn, and A. Rex. (2006) California Gull distribution, abundance, and predation on waterbird eggs and chicks in South San Francisco Bay. Final Report, U. S. Geological Survey, Western Ecological and Research Center, Davis and Vallejo, CA.
External links
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- Patuxent Bird Identification InfoCenter: California gull information and pictures. Archived December 16, 2018, at the Wayback Machine
- California Gull Species Account at Cornell Lab of Ornithology
- California Gull at Animal Diversity Web