Bovey Valley Barbastelle Bats – what next?

Back in the summer of 2019, the five-year Lottery funded Moor than meets the eye scheme was brought to a close with a big Legacy Celebration at Manaton. It was reported that over 150 people listened to “presentations from a range of people who have been involved in the scheme from partner organisations to project leaders. One of the common threads that came out of the afternoon was the huge impact we have made on caring for our wild and built and cultural heritage and the impact that it has on all of us who have worked together.”

It is expected that the legacy will live on for some time from now, but what does that mean for the wildlife of East Dartmoor? One of the best examples of a species that will benefit from Moor than meets the eye is the Barbastelle bat. The IUCN Red List classifies this bat as ‘threatened’ and, across its range, its population is decreasing. Supported by Moor than meets the eye, the Woodland Trust, Natural England and other project partners initiated some detailed research into a colony of barbastelles known to live in the woods of the Bovey Valley. Scientists and volunteers worked together to radio track the bats and, during that time, learned so much about this threatened species; where it roosts, what are its food sources and where it forages. These initial stages of the project will be put to good use in the future management of the woods to ensure the roost sites are protected and other suitable sites will be encouraged to develop in the future. In addition, the IUCN states, “Research is underway to establish conservation requirements for this species. Recommendations include adopting forestry practices that maintain old trees in sufficient numbers.” And, that is what the project will continue to do.

 

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Roost trees and old growth woodland will be protected and enhanced

But this work has left us with another, additional legacy. Over the duration of the project, hourly temperature data has been recorded all along the valley, leading to the development of a detailed heat map. Using this information alongside the radio tracking field data, further analysis has led to a new line of investigation.

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Researchers used the heat map in an Ecological Niche Model to predict other suitable roost sites in the valley. In this model, a number of environmental variables were selected. The most useful variables, it transpired, were the distance from the roost to the nearest watercourse and the mean temperatures during the day and night, (though elevation and slope also played a part in the roost site selection of the barbastelle). This work showed that, in another part of the valley, there was a possibility of other barbastelle roosts that should be investigated so, during the summer of 2019, that is what happened.

Top left: SM4 sound recorder (showing the microphone, recorder and battery) Top right: Heat map of data from SM4 recorders at the potential roost sites. Bottom: Heat map showing the existing roosts (in yellow)

Tom Williams, a local naturalist with expertise in the use of remote electronic sensing, installed a series of bat sound recorders along the river in Lustleigh Cleave. Three of these SM4 recorders were installed in the target areas and were set to record the nocturnal calls of bats (see maps above).

During the active summer season, many bat calls were recorded including many common (pipistrelle and soprano pipistrelle) and other scarcer species (including greater horseshoe and lesser horseshoe bats) but, in amongst those calls, barbastelles were detected. Tom explained the implications of this discovery, “The results of this initial survey work are very encouraging in terms of the ecological niche model’s ability to identify areas with high barbastelle roosting habitat potential within the Bovey Valley woodland. Further field work, such as searches for potential roost features and radio tracking of bats in order to locate roost sites, will help to increase our understanding of how the bats are using these high potential areas and further validate the effectiveness of the model.”

So, the legacy of Moor than meets the eye doesn’t stop there. There is more to do to discover how many of this rare species of bat actually roost in Lustleigh Cleave. We need to answer questions about the locations of their roost trees and, most importantly, what can we do to improve their habitat and provide a more certain future for this previously unrecorded part of the woods.

by Matt Parkins

For further information on the Moor than meets the eye Legacy event, visit the Moor than meets the eye website

For more information on the barbastelle see the IUCN – International Union for Conservation of Nature and Natural Resources: Barbastella barbastellus on the IUCN Red List of Threatened Species

Read more about this research in the following case study: 
Scarce bats in a ecological niche Sept 2019

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