By Tim Tiner
Wind turbines and disease are taking a toll on bat populations here and south of the border. Can a combination of innovative solutions keep these nocturnal mammals off the endangered species list?
In his more than 40 years of studying, teaching and writing about bats, Brock Fenton has never been more gloomy about their prospects in Ontario. “There is not much good news on the horizon,” says the usually amiable, bespectacled professor of biology at the University of Western Ontario (UWO). “It’s very depressing.”
Fenton is distressed by two phenomena simultaneously threatening Ontario’s eight species of bats – one a devastating pandemic, the other the deadly edge of a much-trumpeted green technology. One of Canada’s leading bat authorities, Fenton has made exhaustive studies of the physiology, social behaviour, navigation, diet and habitat of bats. Nevertheless, he maintains that much of bat biology remains a mystery and no one knows the extent of the threats to these species. Bat habitat has been lost, and human intrusion in bat caves is a long-standing problem.
Over the past decade, however, dead bats have also been turning up – sometimes in significant numbers – beneath the roughly 700 wind turbines that have sprouted across the province. Biologists worry that the plan to triple the number of such towers in the next few years could tip a delicate balance for the normally long-lived animals with low reproductive rates.
This past winter delivered another wallop to Ontario’s bats. In March, the province reported its first cases, in the Bancroft-Minden area, of an invasive new fungus that appears most prominently as a white ring around the muzzles of hibernating bats. Though not fully understood, the fungus thrives in the cool, moist conditions inside winter bat caves. It seems to rouse them from hibernation, causing their body temperature to rise from near freezing and burn up the fat reserves they need to survive until spring. Starving, many bats take wing in broad daylight on a futile search for flying insects in subzero weather.
By May, a time when the last bats leave their winter homes, or hibernacula, members of a veterinary organization had found the condition, dubbed “white nose syndrome,” at eight of 12 caves, abandoned mines and other locations they searched, in a band running from just north of Belleville to a little south of Timmins. In most cases, only small numbers of animals were affected, though hundreds died at one location in Timiskaming.
Across the border, the situation is dire. White nose syndrome has killed more than a million bats in the northeastern United States since the fungus was first detected at Howe Cavern, near Albany, in 2006. Of all the bats in affected caves and mines in New York State, Vermont, Massachusetts and Connecticut, approximately 92 percent died. In New York State, the world’s largest known colony of little brown bats (Ontario’s most common species) decreased from almost 200,000 animals to 3,000 in just two years. U.S. experts predict that the syndrome could extirpate the northeastern U.S. population of some 6.5 million little brown bats – representing 85 percent of the region’s hibernating species – within 10 years. As well, inventories in New York State and parts of New England found only 14 northern long-eared bats last winter, down from 742 two years earlier. “They are winning the race to the bottom because they started out at lower numbers,” says Alan Hicks, the mammal specialist with the endangered species unit of New York State’s Department of Environmental Conservation.
The fungus has also been confirmed in Ontario’s northern long-eared bats, the most abundant cave species here. The province’s three other hibernating species, which like long-ears are less concentrated and harder to find in mines and caves than little brown bats, also get white nose syndrome.
Fenton says the pattern is all too clear. “We can predict, with chilling accuracy, that if we go in the caves checked last winter next March, there are going to be thousands of bats dead on the ground.”
Ontario’s largest hibernacula are located in old mines. One near Renfrew has some 30,000 bats.
Another near Barry’s Bay has 20,000. But, according to Fenton, nobody knows how many of the flying nocturnal mammals are in the province or what their effect is on the ecosystem. Although all Ontario bat species catch insects – little browns eat equal to 50 percent and lactating females eat up to 120 percent of their weight in insects per night – as non-game species with no known economic value, bats in the province have never been closely monitored. In the United States, however, white nose syndrome was discovered in New York during an annual, federal and state funded inventory of hibernacula that started 30 years ago with the aim of tracking the threatened Indiana bat, which does not occur in Ontario. “They were able to blow the whistle likely in the first year that the fungus appeared,” says Fenton.
Bats themselves are probably responsible for spreading the spores of the previously unknown fungus (Geomyces destructans), which may have been carried over from Europe by someone, where the fungus was recently found, though its effect there has been less dire than in North America. Each year, about 200,000 people take commercial tours of the Howe Cavern system, where the condition was first discovered.
North American bats have no resistance to the fungus and researchers are at a loss as to how to stop it. They are looking at disinfecting caves with fungicides, rehabilitating infected bats or developing vaccines. So few bats are left in many caves in the northeastern U.S. that whole colonies could be vaccinated in a day, according to Hicks, although there is not yet a vaccine. He believes, however, that Canada could play the leading role in a more permanent solution. “You have a unique situation up there in that you have substantial land masses offshore,” he says, envisioning eastern islands such as Newfoundland or islands in the gulf of the St. Lawrence as places of refuge that could be used to repopulate the mainland.
The possibility that islands may be natural refuges for bats has been suggested as an area of further study by some academics and government officials from the Maritimes, Quebec and Ontario. Saint Mary’s University assistant biology professor Hugh Broders says DNA analysis and radio telemetry could be used to determine the interaction between island and mainland bat populations. “The genetics and field work could complement each other to see if the narrow ocean straits represent a barrier,” says Broders.
But any bat recolonization would be slow. Little brown bats can live up to 35 years but produce just one offspring a year. And studies in England show that 60 percent of young bats, lacking sufficient fat reserves, don’t survive their first winter. “It’s probably the same for our bats,” says Fenton.
“That makes them extremely vulnerable.”