Photo by NPS Photo/ Tim Rains originally posted to https://www.flickr.com/photos/denalinps/5728164052
Introduction
Order: Charadriiformes
Family: Laridae
Genus: Larus
Species: Larus canus
The Mew Gull formerly known, and still sometimes classified as the Short-billed Gull, is the smallest of the “white headed gulls” measuring a length of only 41-46 cm and weighing 360 to 415 grams (Hoffman 1927). Mostly found on beaches and river estuaries, it is also the only “white-headed” gull known to regularly use trees for nesting. Regionally the Mew Gull exists exclusively along the west coast, with breeding regions confined to the far northwest. A well populated species at over 1 million pairs worldwide, the Mew Gull appears widely across Eurasia as well where it is referred to as the Common Gull, causing debate over the inconsistent terminology. Vocalizations and genetic testing is very sparse and has since remained generally unstudied between North American and Eurasian Mew Gulls.(Moskoff and Bevier 2002).
Max Pixel CC0
Their most distinguishing taxonomic features are the ruby colored orbital ring and gape, that stand out in contrast with the pure white of breeding males. Plumage characteristic to the Mew Gull are the the black tips along the outermost primaries, that have pure white spotting towards the most anterior point (Moskoff 2002).
Mew Gulls can be particularly difficult to identify, considering the several variations of melanin and carotenoid concentrations, that can cause both deeper grays and brighter whites. Coincidentally some of these abnormalities replicate the specific identifiers of the Ring-billed Gull (Davis, J.N., and Blumin, L. 2012).
Some subtle differences in a appearance can be difficult to properly identify as their traits aslo vary geographically. Considering the already difficult task of identifying hybridizing gulls, in and out of 4 year molts, these identifiers can be helpful (Moskoff 2002).
The Mew Gull has a dull greenish bill, that is shorter than most gulls, and comes to a pointed slight hook near the tip of the maxilla. The iris is a dull yellow with a greenish tint, and appear almost entirely dark from a distance. Leading up to winter the Mew Gull has a pinkish colored tarsus, however when wintering the coloration changes to an olive gray as they acquire their alternate 1 plumage (Vermeer and Devito 1986)
Basic plumage in breeding males is consistent with an entirely pure white head, gray colored mantle, back, scapulars, and wing coverts.
Definitive Basic plumage in winter showing largely grayish-brown mottling and brushed bown on head and neck. Eyes change to a dark amber or deep olive usually darker in breeding conditions.
Alternative Plumage during February to April when grays become deeper and more solidly gray through the back and scapulars contrasting with paler white wing coverts. The head and ventral torso reach a pure whiter through molt and wear (Moskoff 2002).
Pixabay Photo originally posted by skeeze
Distribution
Mew Gulls are facultative migrants, breeding in a specific area of the northern most portion of Alaska in early May, and distributing along coastal Washington during their non breeding seasons, arriving from July to September (Wahl and Paulson 1991). As shown in the data from previous years of CBC results there have been large variations in populations in an around Olympia over the past 20 years.
This type of population variation is representative of the facultative migrational behavior of the Mew Gull, migration begins along the Washington coast from early March through early May (Campbell 1990).
As shown from the data cross section between Grays Harbor and Olympia, WA, much of the change in population within both counties can be attributed to the exchange between one another.
This graph below represents both counties population of Mew Gulls over time, showing that they are moving more inland on an almost biennial pattern. This can be due to resource availability, climate change, or competition.
Colonial distribution can be in large or small numbers, with as little as one pair to several hundred pairs in a population (Moskoff 2002). They migrate inland, but vary in how far they travel based on climate and resource availability. However the highest concentration of observed Mew Gull population in and along the Puget sound is in the Carr Inlet near Gig Harbor and Tacoma (Jones, Pearson, and Parish 2018). Studies done on the Mew Gulls distribution over time, show that as far North as the Katmai Coast in Alaska, the Mew Gull once belonged to a larger group of diverse bird taxa of various ecological niches, that acted as a substantial food and fashion resource for native Bay Ocean peoples for over 2600 years (Casperson 2012).
version 2.0. In The Birds of North America
Habitat
Mew Gulls are often found in submerged fields and grass pastures, and are well known to be found around sewage-treatment facilities, and storm water retention ponds in coastal environments. Usually in medium to large colonies up to 100 on beaches, estuaries, mudflats. Concentrations consisting of as many as several thousand have been observed off the coast of British Columbia (Campbell 1990)
In and around the Puget Sound, WA, Mew Gull feed exclusively on beach regions, except at low tide, and will defend small patches of territories when food is more limited, however as the Mew Gull is a smaller and less dominant species than a Glaucous-winged Gull, they are not always successful (Tangren 1982)
In a study observing 172 seabird species dependance on year round marine environments, the Mew Gull appear more consistently and widespread than any other species (Gaydos, and Pearson, 2011). This can possibly be a result of their exclusively northwestern leaning habitat, unable or unnecessary to move more inland.
E Bird Map of Field ObservationsEnvironmental changes cause many shorebirds to adapt their nesting strategies to better survive rising sea levels and open-air exposure to predators. The overall nesting strategy of gulls is to avoid avian predation, however in recent years many Mew Gull’s have been observed nesting further inland, having sacrificed one predator for another, as a rise in mammalian predation has increased (Burger, and Gochfeld, 1987)
Surveys done around offshore wind farms in Belgium to better understand impacts of turbines on biodiversity, showed an interesting result of an increased population of Mew Gulls. (Vanermen, Onkelinx, Courtens, Walle, Verstraete, and Stienen 2014) This was speculated to be due to the wind from the turbines causing an upwelling effect at nearshore zones, providing prey that gulls were not originally able to reach on their own (Vanermen 2014).
Accessed from Wikimedia Commons Photo by Guillaume Baviere
The Mew Gull both benefits and shares defensive advantages with various species through interactions. In a study done on nest site locations and proximity to other seabird species the Godwit showed to have a distinct increase in nest success, with closer proximity to Mew Gull colonies, results were shown in in both hatching and post-hatching stages (Swift, Rodewald, and Senner 2018)
Accessed from Wikimedia Commons: Original photo by Elroy Serrao
Studies done on the Mew Gulls distribution over time, show that as far North as the Katmai Coast in Alaska, the Mew Gull once belonged to a larger group of diverse bird taxa of various ecological niches, that acted as a substantial food and fashion resource for native Bay Ocean peoples for over 2600 years (Casperson 2012).
Food Habits
The Mew Gulls diet varies seasonally, but primarily in North America it is consists of
Invertebrates 59%,
Crustaceans (excluding crabs) 12%
crabs 6%
garbage 7%
sewage 16%
(Burger 1988)
During Winter months when food is scarce, they are able to achieve a large portion of their nutrition through algae.
The Mew Gull like most other gulls are well known for their reputation of kleptoparasitism. In many ways this has become a coevolutionary process, for instance in the case of the Mew Gull, the species has been observed migrating in unison with certain benthivorous, frequently joining flocks of Northern Lapwings and European Golden-Plovers ducks who are able to access zebra clams and other shellfish unattainable by the Mew Gulls (Marchowski, Jankowiak, and Wysocki 2016).
Accessed from Wikimedia Commons Photo by Claire Powers
Accessed Wikimedia Commons
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Sounds
Accessed from xeno-canto.org XC448150: Mew Gull (Larus canus) by Patrik Åberg
Call (British Columbia)
Alarm Call
Ian Cruickshank, XC159982. Accessible at www.xeno-canto.org/159982..
Behavior
Breeding Strategy
The Mew Gull is typically a monogamous breeder who can carry a single pair bond for several years. They breed in a wide range of both marine and freshwater habitats, from simple marshes to deep tundras, including the unique strategy of tree nesting, a traditionally uncommon characteristic of other gulls in the Laridae family (Maskoff 2002). Though this unique ability allows for more plasticity in nest options, it also opens them up to a wider range of additional land predators including, coyote’s, cat’s, and foxes (Vermeer and Devito 1986)
Mew Gulls are precocial and give birth to 1 to 5 eggs (67% had 3), sub elliptical eggs which are smooth and slightly glossy (Campbell 1990a). Eggs can hatch in both synchronous and asynchronous fashion with a maximum of 2 days between first and third chick hatching (Whilde 1984).
Accessed from Flickr originally posted by Jukka
The nest is typically made up of vegetation and dry grass formed in a cup structure with a stone placed centrally in the middle to avoid the possibility of spilling over from weather or other environmental activity (Whilde 1984, Burger and Gochfeld). Both sexes of Mew Gulls are able to recognize their nests from previous years, and are known to frequently return to these nests regardless of their condition. In one case a pair was observed returning to the same nest for 23 consecutive years (Bergman 1986)
Hatchling Hierarchy
Studies done on the order of asynchronous chick hatching shows some chemical and behavioral differences between first and third hatchling. Though the third egg in a series receives higher levels of corticosterone and testosterone, they are also smaller and grew faster than the first laid egg (Diaz-Real, Kim, and Velando, 2016). The third hatched chick showed slower breathing rates, signs of needing additional care due to it’s more rapid begging calls, and even less prone to respond to warning calls from parents regarding predators (Diaz-Real 2016).
Accessed from Wikimedia Commons
Literature Cited
Hoffman, R. (1927). Birds of the Pacific states: containing brief biographies and descriptions of about four hundred species with special references to their appearance in the field. Boston, MA: Houghton-Mifflin Co.
Wahl, T. R. and D. R. Paulson. (1991). A guide to bird finding in Washington. 1991, revised 1994 ed. Bellingham, WA: T. R. Wahl.
Vermeer, K. and K. Devito. (1986). The nesting biology of Mew Gulls (Larus canus) on Kennedy Lake, British Columbia, Canada: comparison with Mew Gulls in northern Europe. Colon. Waterbirds 9:95-103.
Whilde, A. (1984). Some aspects of the ecology of a colony of Common Gulls. Irish Birds 2:466-481.
Bergman, G. (1986). Feeding habits, accommodation to man, breeding success and aspects of coloniality in the Common Gull Larus canus. Ornis Fenn. 63:65-78.
Campbell, R. W., N. K. Dawe, I. McTaggart-Cowan, J. M. Cooper, G. W. Kaiser and M. C. E. McNall (1990). The birds of British Columbia, Vol. 2. Diurnal birds of prey through woodpeckers. Victoria: R. Br. Columbia Mus.
Whilde, A. (1984). Some aspects of the ecology of a colony of Common Gulls. Irish Birds 2:466-481.
Diaz-Real, J., Kim, S., & Velando, A. (2016). Hatching hierarchy but not egg-related effects governs behavioral phenotypes in gull chicks. Behavioral Ecology. doi:10.1093/beheco/arw110
Jones T., Pearson S., Parrish J., Ross T., Hodum P., Ward E., Lang J., and Adam S., (2018) “Some like it hot: using citizen science to identify marine bird hotspots in Puget Sound”. Salish Sea Ecosystem Conference. 24. h ps://cedar.wwu.edu/ssec/2018ssec/allsessions/24
Casperson, M. R. (2012). The Importance of Birds in Ocean Bay Subsistence: Results from the Mink Island Site, Katmai National Park and Preserve, Alaska. Arctic Anthropology,49(1), 18-34. doi:10.1353/arc.2012.0012
Swift, R., Rodewald, A., Senner, N.; (2018)Context-dependent costs and benefits of a heterospecific nesting association, Behavioral Ecology, Volume 29, Issue 4, Pages 974–983, https://doi.org/10.1093/beheco/ary042
Vanermen, N., Onkelinx, T., Courtens, W., Walle, M. V., Verstraete, H., & Stienen, E. W. (2014). Seabird avoidance and attraction at an offshore wind farm in the Belgian part of the North Sea. Hydrobiologia,756(1), 51-61. doi:10.1007/s10750-014-2088-x
Marchowski, D., Jankowiak, Ł, & Wysocki, D. (2016). Newly demonstrated foraging method of Herring Gulls and Mew Gulls with benthivorous diving ducks during the nonbreeding period. The Auk,133(1), 31-40. doi:10.1642/auk-15-62.1
Burger, J., & Gochfeld, M. (1987). Nest-Site Selection by Mew Gulls (Larus canus): A Comparison of Marsh and Dry-Land Colonies. The Wilson Bulletin,99(4), 673-687. Retrieved from http://www.jstor.org.evergreen.idm.oclc.org/stable/4162474
Lee, D. S. (2009). Species Profiles of Western North Atlantic Seabirds. The Pelagic Longline Observer Program,47. doi:10.6027/9789289332422-15-en
Tangren, G. V. (1982). Feeding behavior of crows and gulls on a Puget Sound beach. West. Birds 13:1-12.
Burger, J. (1988a). Foraging behavior in gulls: differences in method, prey, and habitat. Colon. Waterbirds 11:9-23.
Gaydos, J., & Pearson, S. (2011). BIRDS AND MAMMALS THAT DEPEND ON THE SALISH SEA: A COMPILATION. Northwestern Naturalist,92(2), 79-94. Retrieved from http://www.jstor.org.evergreen.idm.oclc.org/stable/41300886
Davis, J. N., & Blumin, L. (2012). Multiple color abnormalities in a wintering Mew Gull. Western Birds,43(3), 193-195.
Population Trends and Conservation Issues
Currently in the Western United States alone there are assumed to be upward of 100,000 pairs, ad over 300,00 pairs in Europe, therefore conservation is not a concern. The species appears to have a healthy and expanding population (Lee 2009).
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