In the quest to study bats on Long Island

Last year, biologists at Long Island National Wildlife Refuge Complex in New York conducted a survey to determine which bat species call Long Island home. 

As the summer sun set and people wound down from a long day of work, a team of biologists from the Long Island National Wildlife Refuge Complex and the Biodiversity Research Institute were only just beginning their workday. They walked quietly down refuge roads and trails carrying ropes, poles, and reams of mesh as fine as a hair net. The only light came from their bright headlamps. The biologists were on an important 10-day mission: catching bats.

The health of every bat species is important, but biologists were specifically interested in confirming the presence of the federally threatened northern long-eared bat. “We wanted to locate potential maternity colonies and roost sites on the refuges so we can protect them and appropriately manage the habitats they use,” said Camille Sims, the wildlife technician.

To survey bats, refuge staff and BRI scientists used a technique known as mist netting. Camille Sims, the wildlife technician, describes the mist net as as undetectable, fine netting that acts like an invisible volley ball net, gently capturing bats while they search for food. The nets are monitored continuously from dusk until midnight.

Here you can see what a mist net looks like. Photo by: Dyan Bone, Credit: U.S. Forest Service

“We checked the nets every 10 minutes for bats that may have been captured,” Sims said. “As bats fly down roads and trails where the nets are set up, they hit the net and drop into a small pocket. When we find a bat, we lower the net and gently untangle the bat to retrieve it from the net.”

The biologists weighed the bats, measured their forearms and ears, determined their gender, age, species and reproductive status.  Each bat was also fitted with an identification band and wings were examined for signs of white-nose syndrome, a deadly fungal disease that has devastated bat populations across North America.

Upon completions, bats were safely released back into the night sky.

This little brown bat may look uncomfortable but using a net is a safe and effective way for biologists to catch passing bats. Credit: Ann Froschauer/USFWS

During the 10-day mist netting surveys at two refuges within the Complex — Wertheim and Elizabeth A. Morton — the team of scientists caught 5 eastern red bats and 26 big brown bats at Wertheim National Wildlife Refuge and one eastern red bat and one northern long-eared bat at Elizabeth A. Morton National Wildlife Refuge. The northern long-eared bat also received a radio transmitter to track its location.

The female northern long-eared bats caught during the survey, Credit: USFWS

One of the female eastern red bats caught during the survey, Credit: USFWS

The biological team found no evidence of white-nose syndrome during the summer surveys, but they remained alert for signs of the disease. The fungus that causes white-nose syndrome mostly affects bats during the winter, but scarring on the wings and remnant traces of the fungus can be detected in the summer. The team at the Complex doesn’t know where their bats hibernate, but northern long-eared bats have been found overwintering on Long Island in crawl spaces under buildings.

In 2015 the U.S. Fish and Wildlife Service listed the northern long-eared bat as threatened, primarily due to the threat of white-nose syndrome. In the Northeast region alone, the species has declined by up to 99 percent from pre-white-nose syndrome levels at many hibernation sites.

“As someone who cares about wildlife, I am concerned about it [white-nose syndrome] and I wouldn’t want the disease to spread to the bat populations here on Long Island, so I think it’s great news that we haven’t found signs of the disease here,” said Sims.

After many long nights, the summer surveys were completed and the team could catch up on some much needed sleep – knowing that no evidence of white-nose syndrome was found in the bats they documented on Long Island.

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The surveys mentioned in the blog were conducted from June to July 2017 at Wertheim and Elizabeth Morton National Wildlife Refugess. The Long Island National Wildlife Refuge Complex uses information gathered during the surveys to determine which bat species call the refuge home and identify habitat-use during migration and breeding seasons. This information is important for species protection and best habitat management practices.

To learn more:

U.S. Fish and Wildlife Service, Midwest Region Endangered Species profile on Northern long-eared bat: https://www.fws.gov/midwest/endangered/mammals/nleb/index.html

White-nose syndrome: https://www.whitenosesyndrome.org

Is the coast clear for tricolored bats?

Tricolored bat with visible symptoms of WNS from Chickamauga and Chattanooga National Military Park, Georgia. Photo credit: National Park Service

This winter two scientists will set out to learn  whether tricolored bats that use winter roosts other than caves and mines are susceptible to a deadly bat disease in the coastal plains and forests of North and South Carolina — two of 38 states in the bats’ range.

In the winter of 2016, Dr. Susan Loeb of the U.S. Forest Service and Clemson University and Assistant Professor David Jachowski of Clemson did a pilot study of tricolored bats roosting under two bridges in the upper coastal plain of South Carolina. They found that some bats left the bridge for several days and returned, suggesting that they were using alternate roosts. However, because the researchers did not track bats to these roosts, where the bats were going was unknown.

Now the researchers are expanding their study to find out what alternative roosting sites tricolored bats use and if the behavior of bats and environmental conditions there can protect them from the disease white-nose syndrome (WNS).

WNS, caused by the fungus, Pseudogymnoascus destructans, or Pd, was discovered in New York State in 2007. Now confirmed in 31 states and 5 Canadian provinces, the disease has wiped out some populations of several hibernating bat species, including tricolored bats. At hibernation sites where white-nose syndrome has affected tricolored bats, average overall declines of these bats have been more than 75 percent. As observed by Loeb, these declines have been even higher at some sites in the south.

In their pilot study, Loeb and Jachowski discovered that what sets coastal plain habitats apart is a striking potential difference in temperature tricolored bats encounter at more exposed and warmer sites than at mine and cave habitats.

Temperature is critical to the spread of the WNS fungus because any body temperatures above 64 degrees Fahrenheit might mean a greater chance for the bat’s immune system to fight the fungus over the winter, Loeb said.

She said, however, that such sites might be a double-edged sword. If body temperature remains high, a bat will be less able to enter an extended state of torpor, a short form of hibernation that can last only for a few days. Possibly because of the warmer climate, the coastal plains populations of tricolored  bats might only hibernate on a daily basis to conserve energy.

If bats are able to escape WNS in these alternative habitats but remain more active due to higher outside temperatures, they must forage to survive. Finding available insects in the winter, even in the Carolinas’ warmer coastal plains, might be challenging for the beleaguered bats.

Now, with  $125,925 funding from an FWS research grant, Loeb and Jachowski plan to expand their search for the bat’s winter habitat under bridges and in trees across the coastal plains of the Carolinas. They will be joining the ranks of other FWS-funded researchers such as Dr. Jeremy White in Nebraska and State Biologist Cory Mosby in Maine who have turned their attention to small bat hibernation habitats other than caves and mines.

“The decline of tricolored bats in the southeast is concerning. When the disease first arrived in the region, researchers expected it to not be as bad because the bats could forage.  In some populations, we are seeing 90% declines.” – Susan Loeb

To measure body temperature and foraging, Loeb and Jachowski’s team will outfit temperature-sensitive radio transmitters on the bats at their winter roosts to document body temperatures and activity levels. They will use the transmitters to track bats to what might be an array of winter roosting types in this area free of caves and mines.

When the researchers capture the bats, they will swab and inspect them for the fungus and record data about the roost, such as tree height and cavity depth that might affect temperature. They will also collect fecal samples at the roost site and from the bats to determine whether the bats forage in winter.

Loeb said the study will contribute to a better understanding of bats’ susceptibility to WNS in the southeastern U.S. When the disease was first documented, researchers had hoped the region would host roosts that would be warmer than the northeastern caves and mines where the disease was first found, suggesting that the fungus would not spread to areas where wintering bats’ body temperatures would be higher than the critical 64-degree Fahrenheit threshold. In years since, however, researchers have found that even caves and mines in the southeast are cold enough to allow Pd to thrive.

“The decline of tricolored bats in the southeast is concerning,” Loeb added. “When the disease first arrived in the region, researchers expected it to not be as bad because the bats could forage.  In some populations, we are seeing 90% declines.”

Now with exploration of alternative roosts in the southeast, scientists hope some tricolored bat populations might survive if they can find warm roosts and insects to eat during lean winter months. And in the race to help bats survive WNS, hope is a good place to start.

It’s bat week!

Happy Bat Week!

We’re joining conservation partners across North America this week to celebrate bats. These fascinating animals are vital to a healthy environment, but since 2006 millions of bats have died from a fungal disease called white-nose syndrome.

The U.S. Fish and Wildlife Service leads the nation’s response to this deadly disease, awarding almost $20 million in grants to states, federal agencies and researchers.

One of the projects we funded is a study to determine overwinter survival and behavior of little brown bats and northern long-eared bats at Aeolus Cave in Vermont.

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Researchers from the states of Vermont and New York, along with Vesper Environmental, LLC are using high-tech equipment to study bat movements there.

Tiny passive inducible transponders (PIT tags) glued to the backs of bats emit a unique signal identifying individual bats when they fly through an antenna array at the cave’s entrance.

Data from the research will shed light on whether bats counted in Northeast hibernation sites are survivors of white-nose syndrome and are beginning a population recovery, or remnants of a population that is now slowly declining towards extinction. We hope it’s not the latter!

Last month, we joined the researchers at Aeolus Cave as they captured, banded and tagged bats for the study.

Aeolus Cave is an important hibernation site for little brown bats, which travel from their summer homes around New England and New York to breed there and/or stay for the winter. Bats are long-lived species, often surviving into their teens or twenties, but white-nose syndrome has led to population declines of 90% or more. So it was very exciting to detect a bat in 2014 that was originally PIT-tagged at her New Hampshire summer colony in 2006. This bat has somehow survived through every winter that white-nose syndrome has been documented in North America!

Check out some video of the Aeolus Cave bats in action

Media coverage:

Will some bats survivie white-nose disease long term?

Biologists seek more info on surviving bats

Signs of hope amidst the Northeast’s great bat recession

Bats at Aeolus Cave featured on CBS Sunday Morning!