Two volunteers pause at a predetermined spot in their nighttime walk along a riverbank in rural Ireland. Suddenly, the bat detector one carries comes to life, clicking with the echolocation calls of a Daubenton's myotis on the hunt for aquatic insects. As the clicks accelerate into a "feeding buzz," the second person scans the water's smooth surface with the beam of her flashlight until the bat is spotlighted as it dips to the water and snags an insect with its feet. The pair record the event in their log, then resume their walk.
Similar scenes have been occurring each August alongside waterways throughout much of the country since 2006, when Bat Conservation Ireland launched its very popular Daubenton's myotis monitoring program with a call for volunteers. Nearly 400 people participate, surveying more than 200 sites for these impressive bats. Myotis daubentonii are sometimes called water bats because of their habit of flying low over the water and gaffing insects with their large feet.
"I have now been assisting in the surveys for four years," says volunteer Brigid Geoghegan. "I find myself experiencing rising concern if I notice lower numbers than previous years. It's always interesting to get the end-of-year feedback and [see] the patterns that are emerging. I'm a small cog in a big wheel, but happy to be able to do my bit."
Trained volunteers are an essential part of bat conservation and research in Ireland, which is home to nine bat species (all of them insect eaters), but relatively few bat scientists. Accurate information about Irish bats and their benefits has been rare and misconceptions are common.
Bat Conservation Ireland, founded in 2003, is dedicated exclusively to the conservation of Ireland's bats. We develop and disseminate educational materials, give presentations and lead bat walks. We also conduct nationwide surveys to monitor bat populations, provide a central repository for bat data and serve as an umbrella organization for local bat groups.
Under domestic and European Union legislation, all Irish bat species are protected and we are obliged to monitor them. In 2003, Ireland's Heritage Council commissioned the Bat Conservation Trust (BCT) of the United Kingdom to develop our first nationwide bat-monitoring plan. Key objectives were that non-specialists should be able to conduct the surveys and that the methods would be standardized, repeatable and cost efficient. So BCT conceived an innovative car-based monitoring system. Volunteers drive mapped routes at a set speed at night and record bat passes using time-expansion bat detectors. This system makes it possible to sample bat activity from large areas and varied landscapes in a single evening.
Bat Conservation Ireland has managed this monitoring program since 2004. Volunteers are trained in how to use the equipment during a two-hour training session prior to the survey. Our specially trained volunteers include wildlife rangers, local residents and members of BCIreland.
Each team of two or three people in a single vehicle, with a flashing beacon mounted on top, follows a set route for each survey. One person drives while the others navigate and handle the equipment. They clamp the detector to the passenger-door windows and record the output onto a minidisc. The volunteers drive at 15 miles (24 kilometers) per hour, starting 45 minutes after sunset. The trip takes about two and a half hours. Surveys are conducted once in July and again in August. The recorded sound files are sent back to Bat Conservation Ireland.
We analyze the data, identifying and counting the bat passes in the recorded sound files. With nine years of analyses, we are able to derive robust trends for three of our most common species: the common pipistrelle (Pipistrellus pipistrellus), soprano pipistrelle (P. pygmaeus) and Leisler's bat (Nyctalus leisleri). Based on our data up to 2011, it seems that the pipistrelles are stable or slightly increasing, while the Leisler's bat is increasing.
The two pipistrelles are probably the most common Irish bats and are found across a broad spectrum of habitat types. The Leisler's bat is typically the third most frequently encountered species during the car surveys, although activity levels among species are not, strictly speaking, comparable since they echolocate at different frequencies and different intensities. Monitoring Leisler's bats is particularly important because the species is rare or infrequent in the rest of Europe.
Sixty to 70 volunteers participate in the surveys each year and complete two surveys in a total of 28 locations, each covering almost 350 square miles (900 square kilometers).
"We have done a number of surveys for Bat Conservation Ireland," says Áine Fenner. "The satisfaction comes afterwards, when you see what showed up during the transect. It's good to know that you are contributing information that might not have been available otherwise. Sometimes we have seen live owls and foxes on the route, but mostly we see domestic cats on the prowl. As we come to one particular hot spot for Leisler's on the route, I tend to get anxious to find out if they are still here each year. So far, I have not been disappointed."
Building on the success of the car-monitoring program, we started the Daubenton's myotis waterways project. This is also based on methodology developed by the Bat Conservation Trust. We've been astonished by the enthusiastic response.
After training, our volunteers (in teams of two) each walk 0.6 mile (1 kilometer) along a river or canal bank. They count the number of bat passes for four minutes at each of 10 locations. Each bat pass recorded on the bat detector must be visually confirmed as a Daubenton's myotis with the flashlight, since some Myotis bat species have similar-sounding echolocation calls. We've done quality-control studies and find that our volunteers are accurately identifying these bats. Our statistical analysis suggests a fairly stable trend in Daubenton's bat populations since 2006, although more surveys are needed to confirm this.
Both the waterways and the car-based bat surveys are now cross-border projects that include both the Republic of Ireland and Northern Ireland, with funding from the National Parks and Wildlife Service and the Northern Ireland Environment Agency. Bats, of course, pay no heed to the borders drawn by humans, so our all-island approach is ideal.
When we began this work, Ireland had no central authority for collecting bat-survey data. We began developing our online database for bat records in 2004, and it now contains more than 17,000 bat records, which, for the first time, gives us a good idea of species' distributions and ranges.
By combining our volunteer-based monitoring programs with extensive public education and outreach, Bat Conservation Ireland is producing and disseminating a wealth of new knowledge and understanding about bats. We're also seeing real changes in public attitudes about Irish bats and the benefits they provide to our island. We are committed to continuing our efforts into the future.
NIAMH ROCHE, along with Tina Aughney, coordinates Bat Conservation Ireland's bat-monitoring programs.