28 x 30km squares are surveyed using this survey method in July and August every year. A dedicated network of 70 volunteers carries out the survey work, contributing about 300 hrs of volunteer time per annum. Surveyors are provided with all the survey equipment and given training on how to use it . Routes for the car surveys were first mapped in 2003-2006 and each year survey teams drive the same route using the same method. The surveyors currently use time expansion detectors that record a broad spectrum of ultrasound and record the sounds onto smart phone memory cards. The smart phones also record GPS co-ordinates.
The volunteers then send the data to us and during the winter months we identify and count the number of bats recorded on each survey route.
The scheme provides us with trends in three Irish bat species:
Results for the first 11 years (2003-2013) indicate that Leisler’s bat increased significantly in that time and the soprano pipistrelle also increased, although not to the same extent. The common pipistrelle also increased, although at a slightly lower rate than the other two species. We also collect records for Nathusius’ pipistrelle, along with occasional Myotis bats (which may include a combination of Daubenton’s bat, whiskered bat and Natterer’s bat) and brown long-eared bats.
The scheme has also provided evidence that Leisler’s bats are attracted to white and yellow street lights, since these lamps produce UV wavelengths and in turn attract insect prey for the bats to feed on.
We are currently working on using data collected from the car-based bat monitoring to make predictions for impacts of climate change on Irish bat populations.