Serotine back in Notts?

serotine-in-flight-crop

Serotine in flight / Hugh Clark BCT

The serotine Eptesicus serotinus is one of the UK’s largest bat species. They mainly roost in buildings, particularly old buildings, and are rarely found in trees. They mainly eat flies, moths, beetles and chafers. Serotines are primarily found to the south of the Midlands and in Wales, although a summer roost was recently discovered near Duffield in Derbyshire in 2014 and there are also a handful of bat detector records in Leicestershire – click here for more general info on the serotine.

Way back in November 1986 an adult female serotine was rescued from a house in Dunkirk, Nottingham following re-roofing work. Unfortunately, despite the best rehabilitation efforts of bat carers from the fledgling Nottinghamshire Bat Group, this bat died of its injuries a few weeks later. With no signs of any other bats in this building, and no confirmed bat detector records in the county since then, this remained the only confirmed record of serotine in Nottinghamshire for almost three decades, until recently that is …………..

Since the beginning of our ‘Echolocation Location Project’ in the summer of 2015, we are confident that we have now recorded serotine on at least one occasion, possibly two, during bat surveys completed for this project. On both occasions these bats were recorded in August, in 2015 and 2016, near Norton on the Welbeck Estate in north-west Nottinghamshire. These records may be the most northerly records in England, and possibly Wales.

Both recordings were made by one of our members (Matt Cook) using acoustic bat detecting equipment paid for by the Heritage Lottery Fund. Given the potential significance of these recordings, they were sent for independent ‘blind’ verification by both local and national experts in the acoustic identification of bat species, including Dr Jon Russ. For the first of these records, five out of six of these experienced bat ecologists agreed independently that the recorded bat was serotine. Although the sixth expert was a little less sure, they agreed that serotine could not be ruled out. The call recorded at the second location was very brief and of lower clarity; however, of the four experts that were able to analyse this call, three assessed it as also being serotine.

It should be noted that the echolocation calls of two other bats are quite similar to serotine: noctule Nyctalus noctula and Leisler’s bat N. leisleri, which are also of a similar size to serotine and sometimes found in similar habitat types, such as along woodland edges and over parkland and pasture. This can make the confirmation of a serotine recording difficult in some circumstances, particularly where the bat passed briefly or distantly, was unseen, or the habitat where it was recorded is unknown. It is possible that serotine may have been previously under-recorded in Notts.

One of the recordings is shown below via a sonogram displayed in BatSound v4.03 (Pettersson Elektronik AB).

serotine-sonogram-crop

Although most bats are now hibernating until the Spring, we hope to follow-up these records next year with more bat surveys in this area. This is as well as acquiring more bat detector records across the rest of the county in 2017, all via our ‘Echolocation Location Project’.

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