The fight for our bats

Little Brown Bat with White-Nose Syndrome
Photo by A. Hicks (NYDEC)

White-Nose Syndrome

Bats in Connecticut have found themselves to be the focus of many conservation efforts after White-Nose Syndrome (WNS) spread through the state. WNS gets its name from the white fungus that can be seen growing on the bare skin on the face and wing membranes of affected bats. The fungus, Pseudogymnoascus destructans, infects bats during winter hibernation and causes physiological changes that irritate the bat, and may even cause it to exit the cave during the day. Being awake and active during the winter depletes the fat reserves which should have carried them through to the spring. Because bats are especially vulnerable during hibernation, this disease has a very high kill rate. Some caves in Connecticut have seen up to 95% of hibernating bats killed in one winter. It is estimated that millions of bats across North America have died from WNS since its discovery in 2007. 

Little Brown Bats hibernating in a cave in CT.
White-Nose Syndrome can clearly be seen on the left bat
Photo by P. Fusco

Bats provide an essential ecosystem service which humans value very much: insect control. With the increasing rate of insect-borne diseases affecting people around the country, the value of insectivores (insect eaters) also continues to increase. All of Connecticut's bats are insectivores. One Little-Brown Bat can eat 1,200 mosquitoes in one hour. Connecticut would sorely miss the bat if it were to stop existing in our state, and the Little Brown Bat was one of the species most affected by WNS. The first step to conserving these animals is gathering all the data we can on them. 

Big Brown Bat in flight.
Photo courtesy of Science Magazine and Micheal Durham

What are we doing about WNS?

The research staff at White Memorial have been doing their part to gather data on bats in our area. We participate in three bat-centric surveys: 1. Bat Maternity Counts, 2. Stationary Bat Detecting Microphone, and 3. Mobile Bat Detecting Microphone. 

1. Summer Bat Colony Counts
This survey consists of counting bats as they exit a known roost at dusk. We observe the a colony of Big Brown bats that resides in the storage barn during the summer. These bats exit through the East and West ends of the barn around sunset to hunt for insects. We do this survey twice a year to monitor changes in the population. Once before the pups begin to fly, and once after the pups begin to fly.
This year we counted 193 bats in the initial survey and 363 bats in the second survey.

Intern Abby Wilson sets up the stationary bat detector
over a vernal pool

2. Stationary Bat Detecting Microphone
By using a sophisticated microphone which can detect and record very high frequency noises, we can find spots on the property where bats are using echolocation to hunt for insects at night. We set up this microphone in places we predict bats to be flying; places such as vernal pools, marshes, swamps, etc., and wait a few days. Upon retrieving the device, we read the recorded files through a special software which can analyze the noises and attribute them to species of bat. Each species has a slightly different "call".  
So far over many nights and different locations, we've recorded Big Brown Little Brown, Hoary, Red, and Silver-Haired bats with this microphone.

The white tube contains a microphone (the size
of a smart phone) 

3. Mobile Bat Detecting Microphone
You can probably guess from the name that this survey is similar to the former. It also uses a microphone specially designed to register and record high frequency noise. However, this microphone is much smaller (about the size of a smartphone), and used in a slightly different way. This mobile survey is named such because we use magnets to stick this microphone to the top of the truck, and follow pre-determined transects across all 4,000 acres of the White Memorial property. This method affords us the ability to survey many different habitats in one night, and has yielded some amazing results. We've observed all the same species recorded using the stationary microphone (which took many nights), in one single survey night, which takes about two hours. What an amazing diversity of bats we have here in Connecticut!

The signature sound profile of a Big Brown Bat, Eptesicus fuscus,
labelled Epfu for the first two letters of the genus and species. 

What can you do?

If you want to help the bats, see this website from the CT DEEP: Help CT's Bats 

!!P. destructans spores can last a long time on clothe surfaces, so it is imperative that people exploring caves be mindful to wash all clothes, shoes, and gear before entering a new cave. !!

Bat Count at the Barn

If you like bats, counting, or counting bats, this project may interest you. The Connecticut Department of Energy and Environmental Protection is coordinating with volunteers in order to perform bat colony emergence counts. These counts take place in the later evening and start exactly a half an hour before sunset. In order to do a successful bat count, the temperature can't be too cold and it can't be too windy. 

The goal of the counts is to approximate the size of bat roosts before and after the pups are able to fly. The process of counting the bats is actually very straightforward and simple to do. All you need is a couple of lawn or folding chairs, some bug spray (trust me. You don't want to forget this!) and a means to record the number of bats you see fly out of the roost. Our intern David and myself have already done one bat count at the green barn which yielded an average count of 130 Big Brown Bats. The process will be complete when we do another count after the pups are able to fly (sometime in July). 

The Big Brown Bat roosting area in the barn

The necessity to estimate bat colony size comes from the threat that is currently facing the bat populations of Connecticut: White Nose Syndrome (WNS). WNS is the name given to the disease that is killing off hibernating bats in eastern North America. It has already been documented in 26 states and in 5 Canadian provinces. The disease is named for the white-colored fungus (Pseudogymnoascus destructans) that can appear on the muzzles and wings of affected bats, though it doesn't have to be present in every case. 

Individuals affected by WNS can exhibit erratic behavior in and around their hibernacula (caves where bats hibernate for the winter). WNS causes the bats to become unnecessarily active in the winter, making them lose their fat reserves more quickly. As winter carries on, these bats end up dying off in large numbers. Thus, it's important for us to keep track bat populations to see which ones are at most risk. And because of the high mortality rates seen in other bat populations, being able to save reproducing pairs may be necessary in order to prevent a population collapse.