Winter Bats

05 March 2021 | Posted in Barry Yates , Rye Harbour , mammals
Winter Bats

In our efforts to identify and understand the wildlife that lives in Sussex, bats have always been tricky to identify and an area for experts. But now there is technology to help us - although experts will always needed for some tricky species.

Sound data logger

The technology is in in two parts 

  • Sound loggers like the one above that sit waiting and then turn on when wildlife makes a noise and then records it,
  • a new online analysis tool give us the confidence that only experts previously had to identify bats, small mammals and some crickets - the BTO Acoustic Pipeline

One of the bats we have been focusing on at Rye Harbour Nature Reserve is the rare Nathusius' Pipistrelle bat, it overwinters in Sussex and some of them spend the summer as far away as Latvia! We know this because of a few ringing recoveries. Find out more about Nathusius' Pipistrelle bats by clicking here.

Nathusius migration

In 2015 we left the bat loggers out from 10th December until 4th January 2016. But we didn't determine what was in the sound files. Now we have been able to analyse them and for all those nights the sound loggers sat listening and recorded Nathusius' bats on just three occasions when the nights were warm.

15th December at 7am when the temperature was 12.5 deg C

16th December at 6pm when the temperature was 14.3 deg C

21st December at 11pm when the temperature was 13.0 deg C

So, this February, when the BTO Acoustic Pipeline became available, we analysed the files from five years ago AND we put the loggers out again once the snow had gone. We were amazed that five species of bat were tempted out for a few mild nights when the temperature was above 11.5 deg C, and when there were quite a few midges flying. 

Winter Bats at Rye Harbour

21st February 2021 – 2 Soprano, 2 Nathusius’ Pipistrelle @ 6.00 - 6.20pm

23rd – 1 Daubenton's @ 7.49pm

25th - 5 Soprano, 7 Nathusius’ and 5 Common Pipistrelle and 2 Noctule @ 6.20 - 6.51pm

There are some new and affordable data loggers available, so combined with the analysis tool, this gives the possibility of landscape scale citizen science projects. We are thinking how best to develop the idea. In the meantime we will try some more sound logging when the evening temperatures get back above 11 deg C - it's too cold now in the forecast for the next two weeks!

PS - The data loggers referred to above are called AudioMoth and details are here - BUT it's not yet clear which is the best combination of logger - microphone - case to keep dry, so we haven't got immediate plans... but we are working on it.

Comments

  • Peter Fairclough:

    10 Mar 2021 14:19:00

    Please send me info about the affordable sound loggers. Thanks.

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