Silver gull

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The silver gull (Chroicocephalus novaehollandiae) is a gull in Oceania. It is the most common gull of Australia. It has been found throughout the continent, but particularly at or near coastal areas. It is smaller than the Pacific gull (Larus pacificus), which also lives in Australia.

The silver gull should not be confused with the herring gull, which is called "silver gull" in many other languages (scientific name Larus argentatus, German Template:Lang, French Template:Lang, Dutch Template:Lang), but is a much larger, robust gull with no overlap in range.

Taxonomy

It has traditionally been placed in the genus Larus, as is the case with many gulls, but is now placed in the genus Chroicocephalus. Hartlaub's gull (C. hartlaubii) of South Africa was formerly sometimes considered to be subspecies of the silver gull.<ref>Template:Cite journal</ref>

There are three subspecies:<ref name=ioc>Template:Cite web</ref>

C. n. forsteri (Mathews, 1912) – north and northeast Australia, New Caledonia, Loyalty Islands
C. n. novaehollandiae (Stephens, 1826) – southern Australia and Tasmania
C. n. scopulinus (Forster, JR, 1844) or red-billed gull – New Zealand

Description

Adult

The head, body, and tail of an adult silver gull are white, and the wings are light grey with white-spotted, black tips.<ref name="birdsinbackyards">Template:Cite web</ref> Adults range from Template:Convert in length.<ref name="birdsinbackyards" /> Their wingspan ranges from Template:Convert.<ref name=":0">Template:Cite book</ref> Adults have bright red beaks which gets brighter during breeding or when they get older.<ref name="pizzey" /><ref name=":0" />

Juvenile

Juveniles have brown patterns on their wings, and a dark beak.<ref name=":0" /><ref>Template:Cite web</ref>

Distribution and habitat

Silver gulls are found in all states of Australia,<ref name="pizzey">Template:Cite book</ref> as well as New Zealand and New Caledonia.<ref name="birdsinbackyards" /> It is a common species near human habitations and beaches, having adapted well to urban environments and thriving around shopping centres and garbage dumps. Their successful adaption to urban habitats have seen their population increase in areas of human activity, with the availability of nesting grounds the only limiting factor on population growth.<ref name="birdsinbackyards" />

Silver gulls have twice been recorded in the United States; one bird was shot in August 1947 at the mouth of the Genesee River, Lake Ontario, and another was photographed in Salem County, New Jersey, in autumn 1996. Both are believed to have escaped from captivity.<ref>American Ornithologists' Union (2000): Forty-second supplement to the American Ornithologists' Union Check-list of North American Birds. Auk 117(3): 847–858. DOI: 10.1642/0004-8038(2000)117[0847:FSSTTA]2.0.CO;2.</ref>

Behaviour

The silver gull has a sharp voice consisting of a variety of calls. The most common call is a harsh, high pitched 'kwarwh'.<ref name="birdsinbackyards" />

Feeding

The silver gull naturally feeds on worms, fish, insects and crustaceans. It is a successful scavenger, allowing increased numbers near human settlements. It is known to pester humans for scraps and steal unattended food.<ref name="birdsinbackyards" />

Breeding

Breeding occurs from August to December, typically in large colonies on offshore islands.<ref name="pizzey" /> The nest is located on the ground and consists of seaweed, roots, and plant stems.<ref name="pizzey" /> The nests may be found in low shrubs, rocks and jetties.<ref name="pizzey" /> Typical clutch size is one to three eggs.<ref name="birdsinbackyards" /><ref name="pizzey" /> Often two broods are raised in a year, and both adults share nest-building, incubation and feeding.<ref name="birdsinbackyards" />