Radio tracking Leisler’s bats

In late May and early June Nottinghamshire Bat Group radio-tagged and radio-tracked two Leisler’s bats Nyctalus leisleri in and around Clumber Park with the aim of identifying the first ‘natural’ roosts of this uncommon species in the county as part of our Echolocation Location Project The equipment was funded by the Heritage Lottery Fund or loaned to us by RSK Environment Ltd.

Over ten days our small but dedicated team of volunteer bat conservationists followed the two female Leisler’s bats by day to identify where they roosted, and were also able to follow them for several nights to identify where they commuted and foraged. Our short study established that:

  • The colony – up to 35 bats, presumed females – relied significantly on ‘standard’ wooden bat boxes on trees, such as the one shown below located along woodland edge.

 

  • Some of the colony – a peak count of five bats – also roosted in a cavity at the top of a mature oak Quercus robur tree near the Clumber Park lake, which appeared (from the ground) to comprise a disease and decay feature exploited by woodpeckers – see photos below including the roost being filmed with infra-red ‘night-vision’ equipment. Adjacent to this tree on the ground was also an extensive hollow section of the upper stem of this tree and its associated branches; it seems likely that this may have previously supported this colony of Leisler’s bats but has apparently been torn off in a relatively recent storm – could this explain why the colony is currently so reliant on the bat boxes?

 

  • The two female Leisler’s bats consistently foraged around street-lights and used the same routes to commute to and from them; one bat foraged in an area approximately 3.5 km from the main roost site and the other in an area approximately 6.5 km away. These areas are shown on the maps below.

      

More detail on this study will be provided in a short report in due course. In the meantime Matt Cook, the project lead, would particularly like to thank Marie Athorn for her regular assistance with the fieldwork, along with Ady Orrell, Phil Bych, Julie Straw, Rick Moulds, and the other Nottinghamshire Bat Group volunteers who also helped make these interesting discoveries.

 

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