Ancient, veteran and other listed trees as nest sites for wild honey bee, Apis mellifera, colonies

Abstract

Abstract Implications for insect conservation: Our results show that ancient, veteran and other listed trees provide valuable nesting habitat for wild honey bee colonies in southeast England. Based on an occupancy rate of 2% and a recent estimate of 2 million TSIs in England, it is possible that TSIs support tens of thousands wild honey bee colonies across Britain and that wild colonies are a significant component of total colony numbers in areas with a high density of TSIs (>50 per km2). Wild honey bee (Apis mellifera) colonies naturally nest in old cavity-bearing trees throughout their range, but this important nesting habitat is in global decline. Here we determine the use of ancient, veteran and other listed trees as nest sites by wild honey bee colonies in Britain and investigate the effect of tree size, age, genus and management on occupancy. Over 1,000 trees of special interest (TSIs) were located in southeast England using the Ancient Tree Inventory (ATI) of the Woodland Trust, a charity that protects and promotes trees in Britain. 2% of all TSIs and 4% of TSIs with cavities were occupied by wild honey bee colonies (n=20). Occupancy positively correlated with tree diameter and nearest neighbour distance, suggesting that colonies are more common in large open-grown trees. Wild colonies occupied sweet chestnut (Castanea sativa) and maiden (unmanaged) trees more frequently than expected (7% and 2.7%, respectively, versus 2% overall). Sweet chestnuts have a large mean diameter (1.6m) and proportion of trees with cavities (73%), but these were no different from average in maiden trees (1.4m and 47%, respectively) and did not help explain occupancy.