SynopsisA large water surface, suitable islands for nesting, extensive shallows, rich adjoining farmland and comparative peace help to make Loch Leven internationally important for waterfowl. It has long held the largest concentration of breeding ducks in Britain, consisting in 1966–72 mainly of tufted duck (500–600 pairs) and mallard (400–450 pairs), but also of gadwall (20–30 pairs), wigeon (25–30 pairs), shelduck (5–18 pairs), shoveller (up to 10 pairs) and teal (up to 10 pairs). In winter, it was important for mallard, teal, pochard and in some years for shoveler, and held good numbers of wigeon and goldeneye. These various species differed in the proportion of their food which they obtained from the loch itself. The loch also acted as a winter roost for up to 5000 greylag geese, up to 12 500 pinkfeet and up to 430 whooper swans, all of which fed entirely in nearby fields. The numbers of most species underwent regular seasonal fluctuations, with peaks and troughs in the same months each year; but different species reached peak numbers in different months. In general, waterfowl numbers were greatest in autumn, when the loch held up to 20 000 birds.The status of several species at the loch has changed markedly during the last 100 years. Some such changes were linked with general changes in the ranges and status of the species concerned, but other (more recent) ones with the reduction in macrophytes following eutrophication.
Models to predict the distribution and abundance of breeding ducks in Canada
