Rare Greater Horseshoe Bats found on Skomer Island!

Skomer Island Photo: Leighton Newman

Skomer Island Photo: Leighton Newman

We have had some great news this year with a project confirming that Skomer Island is not only a location for a diverse range of bats but is a regular roost site for the rare Greater Horseshoe Bat.

The study was undertaken by one of the long- term volunteers on Skomer this year, Rob Knott, as his personal project. Rob completed his MSc at Southampton University this year, using acoustics to study bird and bat populations in the tropics so this was a great opportunity for us to find out more about what bat species can be found on the island.

Bats are a species that are important for ecosystem health but unfortunately are highly susceptible to habitat loss and degradation of foraging areas. For this reason there has been a severe decline in some of the 17 bat species in the UK, notably the Greater Horseshoe bat, which has suffered a 90% decline over the past 100 years (Bat Conservation Trust 2010). This species is now only found at a few sites, Pembrokeshire, South West England and more recently in North Wales (Bat Conservation Trust 2018).

Greater Horseshoe Bat

Greater Horseshoe Bat

A bat study was completed on Skomer in the 1990’s and a report produced in 2014 but in both these cases recordings were only obtained in the courtyard at the Farm. This study used the Farm location as well as other sites around the island. Using his experience of picking out potential locations for bats Rob positioned a bat detector in several places on the island including the Farm, Moorey Mere, North Pond and North Haven.

Bat detector on Skomer

Bat detector on Skomer 

During an abseiling excursion for seal monitoring, he was also able to position a bat detector just above the Lantern, which is a large cave looking out from the east side of the island. Visitors to the island may have noticed the bat detector (in his words looking like a NASA moon landing contraption) at the Farm between July and September.

There are six confirmed species of Bat on Skomer

Results of the study found that over the seven recording sites, 380 recordings were obtained with six confirmed species of bat: Common Pipistrelle, Soprano Pipistrelle, Leislers, Noctule, Serotine and Greater Horseshoe. Barbastelle and Greater Long-eared Bats were also suspected but sample sizes were too small for confirmation during this study.

One of the most interesting findings was the presence of the Greater Horseshoe Bat. Rob obtained 58 recordings of this species, which is much higher than in 2014 despite having fewer recording days. Interestingly this species was also found at inland sites, North pond and Moorey Mere as well as at more traditional cave sites at North haven.

One of the factors causing the decline of this species nationally is the use of pesticides which affects the bats’ food source. Skomer is an island free from pesticide use and this may be one of the reasons for the success of Greater Horseshoe bats on the island.

This project has highlighted that Skomer is potentially supporting stable populations of not only a diverse range of bats, but significantly a nationally rare bat species. Hopefully this pilot study will be a justification for further bat study on the island in years to come.

For your chance to see the bats of Skomer Island, why not book a stay in 2020?