Tuesday, 7 March 2006

Early nesting proves risky

There has been rather a lot of noise coming from the river over recent days. Two pairs of Egyptian geese are attempting to lay claim to the same stretch of river, no doubt because of the nesting opportunities that it provides. The loud braying call can best be described as ‘donkey-like’, nasal in quality and of great volume. There can be little doubt that these birds mean business.

The Egyptian goose is something of a Norfolk speciality within Britain. An introduced species, native to large parts of Africa, it became a favourite addition to many estates during the 18th and 19th centuries. The oldest breeding record that I can find for Norfolk is for 1808 but by the end of the 19th Century, it was well established at Blickling, Gunton and Holkham. Unlike many other introduced wildfowl, for example the Canada goose, the Egyptian goose has failed to become established over large parts of the country, the small population in Norfolk expanding very slowly and populations elsewhere going extinct. The most recent survey suggests a population of about 900 birds, about 90% of which are to be found in Norfolk. The highly territorial nature of this species is one possible reason for the low rate of increase; another is the exacting nesting requirements. Egyptian geese typically nest in very large tree cavities, although they may also nest in the bowl created where a large branch arises from the main trunk or in the thick of a gorse bush. It is the ownership of a tree cavity over which my two local pairs seem to be arguing. Perhaps the most important factor in the slow rate of spread is that each pair will only manage to raise an average of 1.6 chicks per year. This may have something to do with the fact that these birds start nesting early in the year. With nests recorded as early as December, it is little wonder that nesting pairs often lose out to periods of bad weather.

Despite its name, the Egyptian goose is not a true goose. Instead it is more closely related to the familiar shelduck, a species with which it shares its hole-nesting habit. Both species undertake a moult migration after the breeding season has ended. While most of our shelduck fly to secure moulting sites off the north coast of Germany (an area known as the Heligoland Bight), Egyptian geese make shorter movements, typically remaining within the county. One of the best known of these sites is at Holkham Park, where 200 birds may gather during July and August each year. However, it is the sight of pairs engaged in territorial display that shows these birds off to their best.

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