The Greensboro Science Center’s Conservation and Research department is actively involved in saving the seven bat species found right here in the Piedmont. Bats in North Carolina are insectivores, meaning they consume insects. Every night from late spring until early fall, you may see bats swooping through the skies, foraging for insects. They are a great, natural pesticide – which is just one of the endearing qualities that makes us want to protect them!
In 2011, researchers began to see signs of White Nose Syndrome (WNS) on hibernating bats in the mountains. WNS is a fungus that adheres to the bats’ skin, particularly their muzzles and wings. The fungus is an irritant that causes the bats to wake from torpor, or hibernation. The process of waking burns a lot of calories, so the bats are hungry, but in winter, there are no insects to eat to sustain them. Large numbers of bats have perished from WNS by burning up their fat reserves before their spring emergence. Some species of bats are more prone to WNS than others, so some species have seen a much more dramatic decline than others.
Researchers across the country, particularly in states impacted by WNS, want to know the abundance and diversity of bats. Researchers collect this information to help construct a long-term understanding of populations before, during and after WNS. It allows scientists to make more informed decisions to combat the disease.
In order to understand what species live here, we sample the population. Since bats use echolocation, we use ultra-sonic recording devices to record calls. We can then interpret the call to identify the species and discover whether they are foraging or navigating their environment. We also use mist-nets to catch bats and obtain diversity and abundance information. This allows us to not only know what species is present, but also the sex ratio, age, and overall health of our bat populations.
Mist-netting is a technique where you string a mist-net between tall poles mounted in the ground like flag poles. Mist nets range in size from 3 meters to 12meters and can be combined to reach up to 30 meters high. Nets are placed at sundown and remain until 1:00am, with researchers checking them every eight minutes. Bats typically go through two rounds of foraging, one at sundown and one just before the sun rises. Mist nets look and feel like hair nets and they are designed such that bats fly into them and safely fall into a net pouch. Researchers carefully remove the bat from the net and place them into a mesh bag.
Once we have a “bat in hand”, we can collect information, including weight (1), species (2), arm length (3), age (4), gender (5), and wing rating (6). Then, we place an ID band on its wing (7) and release it so it can continue foraging. All data collected from these outings are tracked by the state.
1 – Using a spring scale, we weigh the bat in the bag, then we weigh the bag alone and subtract the two numbers to get the bat’s weight.
2 – Eastern Red Bat – identifiable by its reddish-orange color.
3 – The forearm is measured in millimeters using a ruler.
4 – Holding the wing over a light we look for light showing through the knuckles. Juvenile bats have knuckles that are not fused, so light can penetrate through the joint.
5 – Bats are mammals so we look for male or female organs.
6 – A visual examination of the wings allows us to look for damage, WNS fungus or signs of an old issue like a broken bone or torn wing tissue.
7 – A small, lightweight metal band is loosely secured onto the bat’s arm.
The combination of acoustic recordings and mist-netting gives us an understanding of our bat populations. This data allows us to look at trends over time and see how species diversity and abundance change in response to situations like WNS. From this information we can make informed decisions on maintaining bat roosts, including caves, bridges and forests. Wildlife is wild and we are here to guide decisions that allow wildlife to thrive! Every action has an equal and opposite reaction, so we need as much data as we can gather before we make any decision that could alter the natural behaviors or species composition in a habitat.
It is thanks to years of data collection that we have seen a plateau in the decline of WNS-impacted species. It is encouraging to think the large scale declines are coming to an end. We have also seen juveniles of those impacted species, which gives us hope that species are trying to rebound. Bat work will continue to help researchers understand this unique mammal and to help protect their habitats.