It is no exaggeration to say that the decline of the bat populations across New England is becoming an environmental disaster. In the latest surveys conducted by the Vermont Fish and Wildlife Department this winter, the several species of bats that winter there continue to simply disappear at an alarming rate as a result of the white-nose syndrome, a fungal disease affecting cave-hibernating bats. First detected in New York in 2007, it has now spread from Missouri to Nova Scotia.
The white-nose syndrome is a genus of fungi (Fusarium sp.) that is common in the environment and scientists are unsure as to why it is affecting bats over the last few years. What is also confusing is that this disease is so recent yet is becoming so widespread.
“The first inkling of trouble came in January 2007, when a cave explorer spotted an unusual number of bat carcasses around the mouth of a cave in the hills west of Albany, New York,” said Alan Hicks. Mammal Specialist for the New York Department of Environmental Conservation. “Within a month, people in the area were calling in with reports of bats flying around outside in the middle of the day.”
“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 Scott Darling, a scientist with the Vermont Fish and wildlife Dept. “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.”
“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. Because these animals have very low reproductive rates of only one pup per year, it may take a very long time for these populations to come back. We can only speculate what this might mean for bat populations in the Northeast over the next several years.”
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, which 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.”
The Aelous Cave in Dorset, Vt. is of particular concern because it contains the largest hibernating bat population in all of New England. The bat census conducted in that cave in the winter of 2003 counted over 23,000 animals. That number was really an undercount as there are many places in the cave that cannot be reached by surveyors.
“We observed the classic symptoms of the syndrome – bats flying about outside the cave, bats clustered near the cave entrance, dead bats on the snow, and live bats exhibiting the white fungus on their muzzles, for which the affliction is named,’ said Darling in an interview with me back in 2010.
The find in the Aelous Ave has big implications for Massachusetts as many of the bats found in the summer as far east as Cape Cod come from this cave. White-nose has already been detected in a cave in Chester, Massachusetts. Researchers are working furiously at finding out what is the underlying cause of this disease. Scientists are also questioning whether or not this disease is related to the one that has been killing off large portions of our honey bees over the past few years, another problem that has yet to be answered.
Bats play a very important role in the cycle of nature. 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 New England, 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.
Bats are mammals of the Microchiroptera suborder of which there are over 900 species. They are found all over the world except at the two poles. They are the only mammals that truly fly and the only ones whose knees articulate backward.
They are prolific eaters of night-flying insects. They cruise the warm summer night air all over our area consuming prodigious amount of insects. They catch their prey by finding them through echolocation, sending out supersonic cries that bounce off their intended victims and return to them as an echo. They then swoop in a catch the bugs not with their mouths but in a little sac formed by the membrane between their wings and feet. They then reach down and feed from this sac. They will feed most often just after dark and just before dawn when insects are most active.
They are cute little buggers that, when awake and content, vibrate almost like a cat will purr. They live very long lives, with brown bats reaching as much as 30 years of age. It is in our best interest to find out what is killing these poor little folks and helping them return to a healthy population.