The 100 mile Bat - An Unexpected Discovery
Our Ecologist Martin Roche took part in another bat hibernation check on 15th February 2020, this time of two disused railway tunnels in Sussex with the Sussex Bat Group. During the inspection, a greater horseshoe bat (Rhinolophus ferrumequinum) was discovered, which was a surprising find!
The tunnels once formed part of a railway that stretched from the South Downs to Chichester and have been classified as a Site of Special Scientific Interest (SSSI) for their importance as hibernation sites for bats in the UK. The tunnels have gaps in the brickwork and bat boards, which provide roosting opportunities for bats, all of which, were inspected. As well as the greater horseshoe, Daubenton’s, Natterer’s, whiskered and Brandt’s were all recorded.
The greater horseshoe bat is a rare and restricted species in the UK, whose population has declined by 90% in the last 100 years. The greater horseshoes in the tunnels have identification rings and Sussex Bat Group obtained a special licence to handle them so that their ring numbers could be noted.
Sussex Bat Group records showed that one of the male greater horseshoe bats was born and ringed in June 2015 at Woodchester Mansion, Gloucestershire. The young male had not been recorded since August 2015. This means the young greater horseshoe had travelled 137 km (85 miles)! Greater horseshoe bats are generally a sedentary species, travelling up to 50 km on average to find a hibernation roost, with the longest distances recorded being 180 km in Spain in the 1980’s and 320 km in Hungary in the 1990’s. Only a handful of greater horseshoe bats travelling long distances have been recorded in the UK, possibly the longest being a female ringed at Woodchester Mansion in August 2006, travelling over 200 km to Purbeck, Dorset and the Isle of White the following summer.
Woodchester Mansion, Gloucestershire is a Grade I listed building, regarded as an unfinished masterpiece. The Victorian Gothic style house has never been inhabited by humans but has been the home to a colony of greater horseshoe bats for decades. Dr. Roger Ransome has been studying the colony since the 1950s, the longest individual study of a bat colony. Dr. Ransome knows every bat born in the mansion since 1993 and even knows the parentage for many of them. Research (https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2699.2010.02411.x) conducted by Steve Rossiter and Jon Flanders indicates that the greater horseshoe bat was regularly wiped out in the UK during the ice ages, but it has managed to survive in refuge areas in southern Iberia and Anatolia. This species has been able to recolonise the UK between ice ages, through long distance movements, similar to that of the young male discovered in the tunnel.