THE EFFECT ON THE WOODPIGEON (COLUMBA-PALUMBUS) OF THE INTRODUCTION OF OILSEED RAPE INTO BRITAIN

The production of oilseed rape on a large scale in Britain began in 19 73 and the woodpigeon (Columba palumbus) quickly became a major pest o f this crop. This paper uses ringing recovery data to examine the effe cts of the introduction of oilseed rape upon the movements and surviva l of the woodpigeon, and observational data to investigate changes in foraging behaviour. The mean distance travelled between ringing and re covery sites decreased in areas of high oilseed production but increas ed where little oilseed rape was grown. In good arable areas, the intr oduction of oilseed rape did not affect woodpigeon survival but it inc reased woodpigeon mortality in poor arable areas, probably as a result of increased shooting pressure. Oilseed rape is the preferred winter food of woodpigeons and they forage more efficiently on oilseed rape f ields than pastures, the main alternative source of food in winter. Af ter the widespread cultivation of oilseed rape, the average weight los s in a woodpigeon over the winter months became significantly less. Fo llowing the introduction of oilseed rape into Britain, overwinter mort ality from starvation declined and the number of young produced;each s ummer now has a more important effect upon woodpigeon population size.