Special areas of conservation

Two Special Areas of Conservation for horseshoe bats have been designated on Mendip. These are the Mells Valley SAC and the North Somerset and Mendip SAC. The former was selected on the basis of its exceptional greater horseshoe maternity roost, which comprises approximately 12% of the national population. Selection of the North Somerset and Mendip SAC was made primarily because of the presence of caves that offer highly suitable hibernation sites for large numbers of both greater and lesser horseshoe bats.

The UK Biodiversity Action Plan recognises that horseshoe bats have undergone a significant decline in their range, and that fragmentation of foraging habitat may have contributed to this. Recently it has been possible to measure the patterns of habitat use and landscape features that are selected by foraging and commuting horseshoe bats, and also reveal their nightly activity patterns, through a method called radio-tracking. This involves attaching a small electronic transmitter to the back of the bat with a skinbond that allows the bat to be tracked for approximately two weeks before the bond becomes weak and the transmitter falls off. Radio-tracking studies of greater horseshoe bats by researchers at the University of Bristol have been instrumental in the development of mechanisms of landscape improvement around maternity roosts funded through Countryside Stewardship schemes. It is likely that such schemes have contributed towards a 58% increase in the number of greater horseshoe bats at maternity sites in Devon since 1995.

English Nature sponsored two major radio-tracking studies of greater horseshoe bats in the Mendip Hills; at Mells Valley in 2000, and at Cheddar in 1999. Both studies found that the bats foraged primarily along tall overgrown hedgerows and scrub, and in and around woodland. Caves, mines, tunnels and barns were used as night-roosts by the bats to feed and rest before resuming foraging or commuting. The radio-tracking studies revealed the importance of high overgrown hedgerows adjacent to meadows and grazed pasture as a key foraging habitat for greater horseshoes. It is thought likely that the lesser horseshoe bat also favours such habitats. Many of the farms on Mendip are not intensively managed and offer such foraging resources to bats, which together with the abundance of caves and mines offering hibernation sites and farm complexes supplying summer roosts, partly explains the high numbers of both species within the area.