We have just completed a study of our Schwegler Irish bat box schemes that have been in place since 1999, thanks to a grant from the Department of Arts, Heritage and the Gaeltacht. We initially erected the boxes in order to verify a bat detector record that had been published for a barbastelle bat in County Galway and, although we never found a barbastelle, the boxes were soon adopted by many Irish bat species, so we continued with the project. It should be noted that the barbastelle bat has never been recorded by any other method in Ireland since the initial record in 1997.
Over the years we have made 153 visits to the boxes in three woods in County Galway, comprising 7,370 box inspections. Leisler’s, brown long-eareds, Pipistrellus spp., Daubenton’s, Natterer’s and whiskered/Brandt’s were recorded in the boxes and we found differences in the way some of the species’ occupied the boxes. For example, brown long-eareds preferred the 2FN boxes, the pipistrelles preferred 1FFs while Leisler’s showed no clear preferences. And, there was evidence for three species using the boxes as maternity roosts, brown long-eared, Natterer’s and Daubenton’s bats, while the pipistrelles and Leisler’s bats used the boxes in autumn as mating roosts.We also ran an Online Survey to seek information from other bat workers and consultants about their experiences of using bat boxes as mitigation measures. This revealed that Schwegler boxes are the most popular box type recommended and are selected over wooden boxes when available, the main reason for mitigation is loss of roosts and all but one contributor to the survey would recommend bat boxes in the future to replace loss of roosts. Bat boxes are considered suitable alternative roosts for loss of tree roosts, but not maternity roosts in buildings. Very little post-erection monitoring is conducted after development work due to lack of funding and calls into question the validity of proposing boxes as a mitigation measure.
For more information please download the full report here.
