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Naturalised Goose Survey 2000

The jointly organised BTO and Wildfowl and Wetlands Trust (WWT) survey of naturalised geese and swans was undertaken during the spring and summer 2000. The BTO volunteers counted breeding geese and swans, while WWT independently organised counts at recognised summer moulting sites. These two surveys have allowed us to revise estimates of the numbers and distribution of the birds, especially the naturalised geese. Comparing have been made between these results with those obtained by the 1998-91 New Breeding Atlas and the 1991 moult survey organised by WWT.

We were particularly interested in counting Canada and Greylag Goose. However, we were also very keen to learn more about the populations of all "naturalised" species of geese and swans, i.e. descended from escaped or deliberately released birds rather than birds having arrived naturally. Species such as Pink-footed Goose and Barnacle Goose are examples of other commonly observed "feral" species.

The BTO survey recorded geese and swans from 1500 tetrads randomly scattered around the British Isles. The survey indicated that numbers of Canada Geese and Greylag Geese have increased substantially during the period since the New Breeding Atlas such that in 2000 we estimated at about 80,000 and 30,000 birds respectively. In the case of Canada Geese, in addition to a spread in distribution, much of this increase had occurred away from larger waterbodies, including areas where water barely shows up on the map such as on drainage ditches and farm ponds - one observer even found a family of Canada Geese on a grouse moor, miles from any known water. This spread into less obvious goose habitat means that the increase had not been picked up previously by Wetland Bird Survey counts (because few of these small water features are monitored) and counts of moulting flocks (because many successful breeders would not be able to reach these flocks with their unfledged young). If the number of Canada Geese has continued to increase at this rate since the 2000 survey then the population will have exceeded 100,000 birds by the time of the next Atlas (if it hasn't already).