Surveys performed this winter by researchers at the Vermont Fish & Wildlife Department indicate that populations of several species of bats in Vermont continue to shrink due to the devastating effects of white-nose syndrome, a fungal disease affecting cave-hibernating bats.
Fish & Wildlife scientists Scott Darling, Joel Flewelling, and Alyssa Bennett spearheaded a statewide survey of Vermont’s cave-hibernating bat species to continue monitoring the disease since it first hit the state. They have witnessed the effects of the disease, which was first detected in eastern New York in 2006 and was confirmed to have infected Vermont’s bats by 2008. The disease has since spread as far away as Missouri and Nova Scotia in Canada.
“We’ve recorded declines as high as 90 percent during our cave surveys, so we feared a continuation of that drastic rate of decline this winter,” said Darling. “While the rate that we’re losing bats each year appears to have slowed a bit, bat numbers were still considerably lower than in previous surveys. Some species, such as northern long-eared bats, are hardly appearing at all in these caves.”
Bats generate an estimated $3.7 billion a year in benefits to North American agriculture through insect pest control and crop pollination, according to the journal Science. In Vermont, they eat insects that damage crops, torment livestock, or are forest pests. “These unique mammals are the principle predator of flying insects in New England,” said Darling.
“The freefall of bat populations due to white-nose syndrome is something that should be on everyone’s radar right now,” said Darling. “We’re observing the most precipitous decline of a group of species in recorded history and it’s happening right here in our region. Several species have virtually disappeared in less than a decade and we are getting increasing skeptical that these bats will ever return.”
Vermont is home to nine bat species; six species spend winters hibernating in caves and three migrate south. While the species of bats that migrate may be threatened by increased ridgeline wind development, population data on this suite of species is very difficult to obtain. Among Vermont’s cave bats, the little brown bat and northern long-eared bat are state endangered species, small-footed bats are state threatened, and Indiana bats are state and federally endangered species.
According to Darling, there are three avenues to prevent these species from becoming completely extirpated in Vermont. The first, and best option, would be for researchers to find a treatment or a cure for white-nose syndrome and a feasible means of applying it in the wild.
Alternatively, these bats may continue to decline until the few that remain happen to be naturally resistant to the disease. The Vermont Fish & Wildlife Department is participating in a regional study to investigate this possibility. Alyssa Bennett, wildlife technician, cites two adult female little brown bats that the team recaptured six years after they were initially captured and banded by researchers, despite the fact that most other bats in their maternity colony had fallen victim to white-nose syndrome in that time. “While these individual bats may be genetically resistant to white-nose syndrome, they may have also survived due to luck or resilience, or by escaping exposure somehow,” said Bennett.
The third option, whhich Darling refers to as the “Noah’s Ark strategy,” involves holding the bats in captivity during the short time period when they are most vulnerable to white-nose syndrome. The department is working with other agencies to determine the feasibility of such a practice.
“The struggle to save Vermont’s bats continues to be a race against time,” said Darling. “If we’re not successful with these efforts, it’s unclear what we’ll turn to next.”
Vermonters can help bat researchers in their effort to save bats by donating to the nongame wildlife fund on line 29 of their tax return or by going to www.vtfishandwildlife.com.