Thursday 26 June 2008

Lingering Little Gulls bring hope of future breeding


There have been small numbers of little gulls reported from around the coast of Norfolk over recent weeks, a pattern that has become increasingly common throughout the last few years. The little gull is the smallest of our gull species and may be encountered at any time of the year. However, peak numbers are seen during the periods of spring (April to May) and autumn (August to November) passage, as individuals move between the breeding grounds and wintering areas that extend from the southern Irish Sea south to Morocco. There appear to be three distinct breeding populations and it is the westernmost of these, stretching from northwest Russia to southern Scandinavia, that is probably the source of our birds. Interestingly, even though this breeding population has been in decline, it has also shown an expansion westwards (bringing breeding birds into the Netherlands) and this may be why we are increasingly seeing little gulls lingering into the summer months beyond spring passage.

A more detailed examination of these lingering individuals seems to suggest that they are immature birds which presumably do not return to the breeding grounds until they reach maturity. Nevertheless, breeding has been attempted four times in Britain, with one pair getting as far as producing a clutch of three eggs at Rush Hill, Hickling in the summer of 1978. As with the other three nesting attempts, this one failed, most likely through predation. At breeding colonies elsewhere in Europe, little gulls often associate with other gull species, notably black-headed gulls, but they will also associate with marsh terns and avocets. Nesting sites are often alongside shallow freshwater pools, from which the gulls take a range of invertebrate food. Outside of the breeding season, the gulls become essentially coastal or marine in habits, switching to marine invertebrates and small fish.

Most of the birds that are here now will have arrived through the Channel and southern North Sea but observations demonstrate that other birds filter up the west coast of England and then make an overland crossing to bring them into the North Sea. Such overland crossings might seem unusual for a seabird but a number of species are known to use such shortcuts. In the case of the little gull, there are well-documented and annual movements overland, with birds gathering in the Camargue region of southern France before crossing continental Europe to reach the more northerly breeding grounds. The question of whether the species will ever breed here successfully will ultimately be determined by how well the breeding populations in the Netherlands and southern Scandinavia do. If they become well—established then I would expect to see a handful of pairs breed here over the coming decades.

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