The distribution of grey squirrel dreys in farm woodland: the influence of wood area, isolation and management.
Sixty-eight deciduous woodlands, ranging in size from 0.2 to 12.5 ha, were surveyed in East Anglia, UK, and the density of grey squirrels (Sciurus carolinensis) estimated from drey counts. Squirrel dreys were more likely to occur in woods that (i) were larger, (ii) were closer to another wood of at least 5 ha in size, (iii) contained oak (Quercus spp.), beech (Fagus sylvatica) or hazel (Corylus avellana), and (iv) were surrounded by a greater density of hedgerows. The overall density of woodland in the vicinity, the distance to a wood of at least 0.5 ha in size, and the presence/absence of five other tree species did not influence squirrel drey distribution between the woods. In woods that contained squirrel dreys, density was higher in woods with a greater density of large trees (diameter in excess of 50 cm) and in woods which were closer to another wood of at least 0.5 ha in size. Since reducing the probability of squirrels inhabiting a plantation will reduce the risk of young trees being bark-stripped, the results of this study have implications for the design of new farm woodlands.