Tracking Greater horseshoe bats in the Forest of Dean

25/11/2009 14:25:43 Natural England has sponsored a survey to discover the activity patterns of Greater Horseshoe bat, Rhinolophus ferrumequinum whilst at their summer breeding roost at Dean Hall. The roost is situated to the SE of Littledean in the Forest of Dean, Gloucestershire. A total of 10 bats were radio tagged and they were then tracked for a period of five days in June 2008 a similar study was carried out during August 2007 (Billington 2007).

Bats regularly commuted at least 10 kilometres to foraging areas. The total area bats were recorded foraging in covered at least 34 different 1km squares.

Foraging habitat
Bats were recorded foraging primarily around field systems with high hedges or along woodland edge/clearings in the forest. Seven out of the 10 bats were recorded heading into the Forest of Dean though most roamed from site to site rarely spending more than a few minutes in each location. This was conjectured to be the result of lack of insects to eat on account of the poor weather in spring/ early summer.

A total of 11 foraging areas were identified. The three most important areas found during this study period were at Soudley - mainly in clearings/ woodland edge in Smeyd, Foundry, Wallsprings and Dry Woods north of Soudley; along hedgerows at Denny Hill, and Farleys End (hedgerows).

Bat roosts
Three night roosts were identified during the study, two at Denny Hill and another at Blakeney. The Blakeney roost was also found to be a day roost for both Greater horseshoe, Rhinolophus ferrumequinum and Lesser horseshoe bats, Rhinolophus hipposideros; it had not previously been recorded.

No other day roosts were recorded being used by tagged bats but up to 5 bats (10-50%) were absent each day from Dean Hall. Radio tracked bats were recorded near at least two known underground hibernation sites it is likely some bats day roosted in them.

Bats came back late in spring
This year the bats came back to Dean Hall several weeks later than in other years, and gave birth about two weeks later than in 2007 (David Priddis pers. com.) This is believed to be a result mainly of poor weather and lack of insects in early 2008.

The main commuting routes used by the bats leaving the roost during this study from Dean Hall were identified as a track to the east of the Hall and south from the roost.