The red fox Vulpes vulpes as a scavenger and predator of sheep in west Scotland
This thesis considers the role of the fox as a scavenger and predator, the management and performance of hill sheep, methods of controlling foxes and their effectiveness, and trends in fox populations. Sheep carrion was abundant in April and May on two study areas, but scarce in July-August and January-February. It predominated in the food of foxes during the first half-year, but field voles were more important in the second half. Fluctuations in numbers of foxes were associated with vole peeks, but carrion may support more foxes than could otherwise subsist on the scanty live prey. Foxes killed about 1% of the estimated lamb crop during three years but 2% in a year when foxes were numerous. Golden eagles killed up to 1% of the lamb crop. Both predators killed lambs aged 1-5 days, in good condition with aieauate fat reserves. More foxes were killed each winter from 1973-74 to 1976-77 on twenty-five estates throughout Scotland but the number or breeding dens remained the same. It follows that killing foxes in winter, as widely practised, is ineffective in reducing the breeding population. Dens were not randomly spaced. They were commonest on agricultural land and fewest in deer forest. No known change in land use or control methods can account for the increase in foxes in Scotland during the last thirty years. New methods of controlling foxes, such as aversion therapy or chemosterilants, are unlikely to appear within the next few years. Meantime an improvement in the management of hill sheep is more likely to increase the production of lambs than bigger efforts to kill foxes.