Decline in bats could have adverse ecological impact, SCSU professor says
NEW HAVEN — While Miranda Dunbar, an associate professor of biology at Southern Connecticut State University, studies the physiology and ecology of mammals, bats stick out to her for “doing everything wrong” as mammals — such as exhibiting reciprocal altruism and the ability to adapt to virtually any structure or habitat.
In fact, according to Dunbar, while humans tend to create negative connotations for nocturnal animals as creepy or evil, bats are not just clever, they also have some traits that humanity could stand to emulate, Dunbar said.
“We’re finding that bats have an enormous vocabulary of sorts, and it speaks volumes to their intelligence,” she said in reference to the specific calls bats make.
“They have calls only their friends recognize, calls only their family recognize and calls between parent and offspring that we liken to lullabies,” she said.
But within the last decade, a fungus called Pseudogymnoascus destructans has rapidly spread among the bat population in New England, cuasing an infection called white-nose syndrome. According to Dunbar, the effects leave a clump of white fuzz on bats’ muzzles and wings, which deteriorates the quality of their skin.
“It’s a devastating epidemic,” she said.
Because the effects of white-nose syndrome often take place while bats are hibernating, Dunbar said bats are often awakened from their slumber during the winter so the immune system can take care of the infection, but they are subsequently “emaciated” when their fat reserves are spent during the hibernation period.
Rising global temperatures have created an atmosphere for the fungus to survive in colder months in cave settings, Dunbar said. Additionally, the fungus can often be transported into caves through human contact.
According to the state Department of Energy and Environmental Protection, little brown bats and big brown bats are the two most common species in the state, and are much more populous than the other six species native to Connecticut.
The DEEP says a little brown bat’s wingspan is about 8-10 inches, whereas a big brown bat’s wingspan is about 1 foot.
Although the little brown bat species population has been destroyed by the white-nose syndrome infection, Dunbar said the research community has shifted to focus on positives: big brown bats appear to be surviving, she said. She anticipates that much of the research this winter will focus on what is unique about the survivors of white-nose syndrome.
“There’s been a shift in the field,” she said.
Although many people may hold a position of ambivalence, annoyance or fear toward bats, Dunbar said the animal is a major boon to Connecticut’s ecosystem.
“Bats provide more ecosystem services than so many other mammals,” she said. “Bats worldwide are pollinators and seed dispersers. Locally in Connecticut, they are nature’s best pesticide.”
Bats feed on pests that pose a threat to summer recreation activities and crops and livestock. Dunbar said that, as the insect population increases, farmers are using more pesticides and the overall crop yield is falling. A “A Citizen’s Guide to Creating Pollinator Habitat in Connecticut” by Dr. Kimberly Stoner, of the Connecticut Agricultural Experiment Station. notes that bats also serve as pollinators of some plant species.
The U.S. Fish and Wildlife Service announced in an online post in September about $1 million in grants to 39 states and the District of Columbia to support the “fight against the bat-killing fungal disease white-nose syndrome,” noting that the disease “has killed millions of North American bats in recent years, decimating many populations and putting several species at additional risk of extinction.”
“Bats are crucial to our nation’s farmers and foresters, helping control pest insects such as beetles and locusts and significantly reducing the amount of toxic pesticides that would otherwise be needed,” according to the service. “Studies estimate bats save farmers at least $3.7 billion per year in lost crop revenue and pesticide savings.”
The “funds will help states support a national strategy for the disease, which includes increasing bat survival rates, preventing further spread and preparing for the potential arrival of the disease in new areas,” the wildlife service noted.
According to the DEEP, one little brown bat can eat 1,200 mosquitoes in an hour, which Dunbar said is two to three times the bat’s weight.
Additionally, while global warming appears to have led to the sustained viability of the white-nose syndrome fungus, it also increases the life span of the pests that bats ordinarily feed on, increasing the risk for a pandemic.
“It begs the question of malaria and other mosquito-borne illnesses that could require attention in the future,” she said. “It’ll be interesting to look at bat decline and whether there’s an increase in West Nile Virus.”
The DEEP Wildlife Division has been actively engaged in studying WNS at the state, regional and national levels since 2007, officials said.
“This issue is extremely important and has significant impacts to both ecosystem health and economics,” DEEP spokesman Chris Collibee said. “It continues to be one of our major research and management priorities. We are always happy to see that other partners have an interest in and concern for this devastating wildlife disease.”
Dunbar said ecologists are showing interest in researching global health risks under global warming, and she expects there may be answers soon.
Even if people don’t often see the nocturnal creatures, Dunbar said she suspects people may begin to notice bats’ absence if white-nose syndrome doesn’t slow down.