Back at the time of the last winter atlas, in the period between 1981 and 1984, Greylag Geese were mostly concentrated in Scotland during the winter months. The map alongside shows the wintering areas of these birds, most of which were of Icelandic provenance at that time. In the eighties, the lowland areas of southern and eastern Scotland held large numbers, with birds first attracted by spilt grain on stubble fields and then taking the new growth of cereals and grazing fields. Although there were economic gains to be made, through the money spent by goose-hunters, there were costs too. Grazing geese can damage the new growth of autumn-sown cereals, both by nibbling and waddling around in muddy conditions, and can also compete with cattle and sheep for spring grass.
The change since the 1980s has been massive. The second map illustrates this clearly, with a spread of wintering birds across most of England, through the west coast of Scotland and into more of the Scottish islands. It’s a complicated story; in Orkney for instance, wintering birds comprise local breeders and Icelandic visitors. A longer grass-growing season may well have suited Greylag Geese. As will be clear in Bird Atlas 2007-11, this is not just a matter of range change; winter densities in parts of England are now little different from the Scottish heartlands. With Icelandic birds wintering more widely across Ireland, where there may be plenty of space for further expansion.
One of the key outputs from Bird Atlas 2007-11 is a much more comprehensive set of data on introduced and invasive species. Our experiences with Canada Geese and Ring-necked Parakeets have taught us the importance of monitoring these populations.
At the time of the 1968-72 Breeding Atlas, Greylag populations in England and southern and eastern Scotland were focused on release sites of youngsters which had been transferred from Scottish breeding populations. These days the situation is complex, in that experts agree that there is no clear distinction between these naturalised (or “feral”) birds and native breeding populations, especially in Scotland. See Mitchell, C, R Hearn & D Stroud. 2012. The merging of populations of Greylag Geese breeding in Britian. British Birds 105: 498-505.
In the 1968-72 Breeding Atlas there was evidence of confirmed/probable breeding in 126 10-km squares in Britain and 7 in Ireland. By 1988-91 the comparable figures were 417 and 14 and this time they are 1508 and 71. The spread of the species is shown in the fourth map, with most of the expansion in England and Wales based around the areas of reintroductions that took place nearly forty years ago. As reported in the Sharrock Atlas, ‘By 1970, WAGBI had released 938 hand-reared Greylags at 333 sites in 13 English and Welsh counties (Ellwood 1971)’. It would be interesting to know exactly how many birds there are now!