30 Days Wild - Day 30: Saving the bats til last

Well it's the last day of "30 days wild", what shall I post for our last wild activity of the month?....

Why not go for the obvious, which I've somehow managed to avoid posting until now?!

Tonight we'll be be undertaking a bat survey on a site in the hills above Huddersfield. Bat surveys are the mainstay of our work from the end of June through to the end of September, albeit with a scattering of other surveys and habitat management work in between. We usually get called in to survey a building when someone wants to undertake building work that requires planning permission as the planners need to be satisfied that the favourable conservation status of these European protected species will not be significantly affected by the proposals.

Its a habitat assessment and "emergence survey" tonight. 

First we'll be checking all around and inside the building in question for bats or signs of bat use which might be droppings, staining or even the sound of bat chatter if there is a big roost present - particularly on a hot day like today. We record all of the features that bats might use for roosting which could be anything from a single bit of missing mortar under a ridge tile, up to a large loft where bats could fly up and down until they're ready to come out after dark.

Once on that's done we set ourselves up in suitable positions outside the building, at least 15 minutes before sunset, waiting for any bats roosting in the building to emerge. Different bat species emerge at different stages of darkness starting with the larger bats (noctule and Leisler's bats), which often come out before sunset and can be easily mistaken for birds flying high across the sky. Then the pipistrelle species are next, which are usually all out within 30 minutes of sunset. At the opposite end of the spectrum the long-eared bats might not emerge from their roosts until 1 hour after sunset, when it's almost completely dark. We watch the building until 1 hour and 30 minutes after sunset to make sure we don't miss any emerging bats.

Every site can come up with surprises, sometimes we don't have a single bat, other nights we might have a soprano pipistrelle maternity roost of 200 bats! Who knows that tonight's survey will bring.

We don't often get to see bats this close up - this was taken during one of our bat box checks at Seckar Wood

Well done to everyone else who's being taking part in 30 Days Wild.