Wednesday, 14 November 2012

Greater Horseshoe Bat - A Pleasant Surprise

It was an early start this morning as we had to travel to Somerset and survey a site before heading onto Taunton for a meeting. We arrived at the site in plenty of time and did what we had to do before coming across a small cave set in a limestone escarpment.

Small Cave in Limestone Escarpment

The cave itself looked fairly shallow, but on entering, it was possible to see that the cave extended upwards into the limestone. Looking around we located loads of large bat droppings on the cave floor; the droppings were in three parts and measured about 10 millimetres in length and about 2.5 millimetres wide. The size and shape of the droppings looked very reminiscent of greater horseshoe bats, so we investigated further.

Large Bat Droppings on Floor of Cave

Looking up there was the bat, a greater horseshoe, wings wrapped around it and torpid. Greater horseshoe bats are mainly restricted to the South-west of England and South Wales so it was not an unexpected find, but nonetheless still exciting.

Roosting Greater Horseshoe

Horseshoe bats are from the genus Rhinolophus and there are two species resident in the UK, Lesser R. hipposideros and greater R. ferrumequinum. When roosting the two species are readily distinguished since greater horseshoe is tablespoon sized, where as lesser horseshoe is teaspoon sized. The two species habitat preferences include woodlands and linear features such as mature hedgerows and woodland edges. Lesser Horseshoes echolocate at around 110 kilohertz, whereas greater horseshoes at around 82kHz. These are species that we rarely encounter in Hampshire so it is always good to see one when surveying out of the county.

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