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. !!

Surveying White Memorial's Bat Population

 

 This summer, White Memorial adds its efforts to an ongoing survey of Connecticut's bat species. Begun in 2010 by the Department of Energy and Environmental Protection, the survey uses sound recordings to monitor bat activity. Starting a half-hour after sunset and continuing until late at night, White Memorial's research technicians drive a 24-mile route through the woods roads of the property, using a truck-mounted microphone to record high-pitched sounds. The microphone is sensitive to sounds well above the range of human hearing, and records the calls of bats as they seek out insects for food, along with any high-pitched background noise from nearby telephone wires, insects, and radio transmissions. We'll pass these recordings on to the DEEP, where computer analysis will distinguish the bat calls from surrounding noise and identify the bats by species based on their unique sound patterns. We'll likely find evidence of big brown bats (Eptesicus fuscus), little brown bats (Myotis lucifugus), and northern long-eared bats (Myotis septentrionalis), all known to inhabit White Memorial's property.


     Relying on acoustic recordings of bats allows us to form a much more detailed picture of bat populations, distributions, and activity than do older methods such as counting bats caught in mist nets. Furthermore, as white nose syndrome continues to decimate bat populations in the eastern United States, bat monitoring has become increasingly important. The white nose fungus (Pseudogymnoascus destructans) has been present in Connecticut since the winter of 2007-2008, when it was found among hibernating bats in northern Litchfield county. Bats affected by the fungus exhaust their fat reserves and die during their winter hibernation. Monitoring efforts at White Memorial and in towns around Connecticut will help measure surviving bat populations, determine which species are affected and not affected, and provide long-term data against which management efforts can be judged.

West Nile Virus Continues Killing Bird Species Commonly Observed At White Memorial

West Nile Virus was first documented in Connecticut and North America in 1999.  The mosquito-borne disease has spread throughout the continent, meanwhile killing millions of birds as it spread.  American Crow, Common Raven, and Blue Jay were the first birds observed dying in Connecticut.  Fortunately, these populations were able to recover since then, but many other bird species have not faired as well, including Purple Finch and Tufted Titmouse.  A brief article that outlines the major findings of this paper can be found here.  

The original publication is an important examination of how emerging infectious diseases are impacting and will continue to impact many bird species.  This lesson is not a new one for us in Connecticut.  We've observed how White Nose Syndrome has severely decimated several bat species that were regarded to as common a decade ago.  We are learning about new pathogens that are spreading around the world and could have devistating impacts to very important species we conserve.    Our best course of action for the long-term conservation of our natural resources is to prevent the introduction of these pathogens and pests from entering the continent.  

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.

Post-Volant Emergence Count of Bat Colony at the Green Barn

On July 25^th a second count of the bat colony in the Green Barn yielded a total of 167 Big Brown bats. The previous bat survey took place May 30^th when James Fischer and I counted 127 bats. The May count represents the number of bats before the pups begin to fly (pre-volant) and the July count represents the number of bats after the pups begin flying (post-volant). Therefore, the comparison of this data gives us reliable information about reproduction rate, as well as population growth. It is always a positive sign to see the number of bats increase, although we would have liked to have seen an even higher count, such as in 2010, when 286 bats were counted at the Green Barn. Since White Nose Syndrome is still spreading and devastating bat colonies, the data that is collected is critical in helping researchers measure the fallout of this disease and further explore other possible factors affecting bat population. We have observed that weather conditions greatly affect whether or not bats leave their roost at sunset. On July 18^th we attempted to do a post-volant count after a very hot and humid day with late afternoon thunderstorms. We were able to count only 105 bats emerging from the Green Barn and afterwards concluded that the data was inaccurate due to weather. In my opinion, bats will always be a unique and mystifying species. Their imperative role in our ecosystem should always be appreciated and we need to continue to protect these creatures as much as possible.


Two of Gerri Griswold's Big Brown bats.

Bat Maternity Colony Monitoring

A bat maternity colony monitoring project was held Wednesday, May 30^th at White Memorial. The survey’s purpose is to identify and evaluate the size of bat maternity roosts. This is achieved by conducting an emergence count of a specific roost before the pups begin to fly and an additional count after the pups begin to fly (sometime during the month of July). The emergence count started at 7:30 pm right before dusk, when the bats start to leave their den to feed. James Fischer and I, the surveyors, stood on either side of the barn and counted all of the bats that emerge.

The site that we decided would be most appropriate to monitor a bat colony is the two-story, open barn, known as the Green Barn, that holds White Memorial’s truck, van, and miscellaneous landscaping tools. There is a well-known roost of Big Brown bats (Eptesicus fuscus) that occupy the ceiling of the barn. From 7:30 to 9:09 pm we counted a total of 127 bats emerging from gaps at the top edge of the barn. Big Brown bats have black wings with a brown furry back and paler fur below. They are a very common bat in Connecticut, and typically are found in forests, but they can also live in crevices of buildings and caves.

Green Barn where bat survey took place.

Big Brown Bat
Photo by Jim White
http://02b93fb.netsolhost.com/

Opening from which most of the bats emerged.

It is important to document colony declines and losses to accurately track population change, especially to monitor the effects of White-Nose Syndrome, which since 2006, has killed over 5.7 million bats in Eastern North America. Bats play a crucial role in maintaining an ecosystem balance and consume thousands of mosquitoes and other insects every night.

This project is hosted by Connecticut DEEP Wildlife Division, who encourage volunteers to make counts wherever a bat colony is known to exist. Researching a wildlife disease is expensive, therefore more committed volunteers will help DEEP retain and use grant money to help combat this destructive disease.  

Bat Maternity Roost Microclimate Monitoring

(l to r) Ethan Toczko and Brian Blais (CT DEEP, Wildlife Division)
download data collected by datalogger.  

The datalogger is located in rafters of White Memorial's Green Barn
 and collects temperature and relative humidity reading periodically.  

Ethan Toczko and Brian Blais (CT DEEP, Wildlife Diversity Unit Technicians) downloaded some information that has been steadily collected for the past summer season.  Jenny Dickson (CT DEEP, Supervising Wildlife Biologist) is studying the microclimate of Big Brown Bat maternity roosts and associating this information with prevalence of White Nose Syndrome.  White Nose Syndrome (WNS) is an emerging infectious disease that kills bats primarily during the winter season while they are hibernating but has been observed in young animals who are dispersing from the roosts where they were born.  Recently, the disease causing agent was verified as a fungus that is native to Europe and brought to North America.  This invasive species has caused as much as 90% of the bats to die each year while hibernating in Connecticut's underground cave-like structures.  Fortunately, Big Brown Bats are the only hibernating bat species in CT not experiencing this level of mortality but some animals do die from WNS each year.  The datalogger is located in the rafters of White Memorial's Green Barn and collects temperature and relative humidity readings.  Although the data is collected continuously and culminates in thousands of data points, we only have to pull out our tallest extension ladder to download the data once a year!  Finally, technology that creates less work!

Big Brown Bat censusing

Big Brown Bats roosting

photo from http://www.bu.edu/


Big Brown Bat in flight

photo from http://www.uwgb.edu/

White Memorial's Green Barn, which is located in the Main Area right behind the Museum, has hosted a Big Brown Bat colony for as long as anyone can remember. Since 1999, we have conducted sporadic censuses of this colony, usually as they exit in the evening to feed. This work has become increasingly important in the past few years with White Nose Syndrome decimating bat populations. Little Brown Bats are now greatly diminshed in numbers around this area because of this disease, but Big Brown Bats are still holding on in good numbers. They may not be affected by this disease quite as badly as other bats, or it is just a matter of time before it hits them hard, too. This year they had problems dealing with prolonged cold, wet weather in June. We found a total of 22 dead pups on the floor of the barn during this time period. Our censusing has also been adversely impacted by persistant lousy weather this year. Bats are not inclined to fly in the rain, so we don't try to census them under those conditions. With many other tasks to perform, it has been hard to find time on nice evenings to count the bats. On one such evening in early July I counted 193 bats exiting the barn. I didn't have another opportunity until Saturday, 8/6, when the bat census was supposed to be a major component of our "Serenade for the Bats" program for the public. However, heavy rain descended upon us about 5 minutes into the count after 70 bats had emerged. Not only did bats cease to come out, but the bats that had just come out went right back in. We quit counting them at that point. The rain didn't quit until the next day. I was a lot luckier the following Saturday, 8/13. The weather was mostly clear and warm with a light breeze. I parked myself on the northwest side of the barn where I could see the primary exit point under the peak of the roof on the west side and the secondary exit out through the front doors on the north side. I started watching for bats at 7:35 p.m., but didn't see the first one emerge until 7:47. The peak action occurred between 7:55 and 8:05. The last bat exited the building at 8:17. I went into the barn at 8:25 to see if any bats were still there, and didn't see any. The total that night was 164 bats, with all but 13 exiting from the west side. Almost all of them flew toward the Lake Trail and Ongley Field. The weather this past Saturday evening, 8/20, was also perfect for the bats and for us to count them. This time it was part of our "Things That Go Bump In The Night" program for the public. Twenty people participated in this walk which wound up at the Green Barn at 7:40 p.m. We postioned ourselves to see the west and north sides easily, and were rewarded with a total count of 149 bats between 7:45 and 8:20 p.m. Just like last week, the peak activity occurred around 8 p.m. When we went into the barn at 8:25 to check for remaining bats we didn't see any. All but 9 of the bats had exited from the west side of the building. We can't account for the decrease in bats with any certainty. We could have missed seeing bats exit the east or south sides of the building, or they may have been roosting in a different building, or they may have left the area, or they may have been eaten by an owl or other predator, or they may have died from some other cause. We did look for dead bodies in the barn and didn't see any. It is interesting to note that I saw a Great Horned Owl perched on the barn's roof right over the exit hole on Tuesday, 8/9, and we heard a Barred Owl hooting from the Interpretive Trail on Thursday, 8/11. We'll see what the rest of the summer brings for bat numbers as we continue to try to count them on a weekly basis. The more people helping to count, the better, so come on out.