Nest site selection, management and breeding success of crested tits Parus Cristatus at Abernethy forest, Strathspey

Crested Tits at Abernethy Forest RSPB nature reserve selected broad stumps and dead trees of Scots Pine in which they excavated nest chambers in the rotten sapwood of the trunks. Given the size requirements for nest chambers, only frees with a diameter greater than about 20 cm are suitable, as sapwood depth is correlated with trunk diameter. There was avoidance of the south-west quadrant of dead trees and stumps, despite the greater depth of soft sapwood on the west side of dead trees. Prevailing weather or sunlight may affect aspect selection. Nests occurred in old open forest and plantations where the density of the surrounding frees averaged 290 per ha. Mean clutch size was 5.5 eggs and nest success was 50%. The provision of potential nest sites by cutting 'high' stumps has shown that it takes about nine years for the sapwood to rot sufficiently for excavation. However, none has been used to date, perhaps because of the small trunk diameters. It is recommended that future stumps should be cut at least 2 m from the ground and have a trunk diameter of over 30 cm.