By DAN PELTON Orangeville Citizen
While the bat will never make nature’s cute and cuddly list, it is a vital part of the ecosystem and its population is being threatened on a number of fronts.
Large numbers of bats have reportedly been killed and injured by wind turbines, and a disease called “white nose syndrome” threatens to kill bats by the hundreds of thousands.
To point out an immediate benefit of the bat is to consider that a single small brown bat can, in an hour, consume up to 1,000 mosquitoes that otherwise might be buzzing around our heads or gorging on our blood.
A nursing mother bat eats more than her own body weight nightly – up to 4,500 insects.
It should also be taken into account that plants providing imported fruits from warmer climates are as likely to be pollinated by bats as they are by bees.
White nose syndrome was detected for the first time in Ontario – in the Bancroft, Minden area – earlier this month. Meanwhile, it is being held responsible for killing hundreds of thousands of bats in the northeastern U.S.
It was first identified in a cave near Albany, New York, in 2006. It has since spread throughout the New England states and as far south as Tennessee.
The condition is dubbed white nose syndrome because some affected bats have visible rings of white fungus around their faces. Cause of the syndrome is still under investigation.
Affected bats are prone to emaciation and dehydration and behavioural changes, such as flying in daylight during the winter.
White nose syndrome is not considered a human health issue.
It has been circulating through caves in the northeastern U.S. for at least three years and some caves have been visited by thousands of people, during this time, with no illnesses reported.
Although the condition is not well understood, there is speculation that human activity in caves is contributing to its spread.
In the meantime, there is debate over how much harm wind turbines are causing the bat population.
Local opponents of wind farms say hundreds of dead bats are being found near the turbines.
A University of Calgary bat mortality study, conducted between 2006 and 2008, determined that the vast majority of bats found dead below turbines near Pincher Creek, Alberta, suffered severe injuries to their respiratory systems consistent with a sudden drop in air pressure – called barotrauma – that occurred when the animals got close to turbine blades.
The study showed that 90 per cent of the bats examined after death showed signs of internal hemorrhaging consistent with barotraumas, while only about half of the bats showed any evidence of direct contact with the blades.
Bats would be more susceptible to barotrauma than birds, insofar as their lungs are like those of other mammals – balloonlike, with two-way airflow ending in thin flexible sacs surrounded by capillaries. When outside pressure drops, those sacs can overexpand, bursting the capillaries around them.
Bird lungs, on the other hand, are more rigid and tube-like, with one-way circular airflow passing over and around capillaries. That rigid system can better withstand sudden drops in air pressure.
One of the most extensive studies of the effects wind turbines have on bats was carried out at a 42-turbine facility in West Virginia.
One finding was that bats that had just experienced a near-miss with moving blade, would linger at the site rather than fly away.
This behaviour has led to speculation, with no confirmation, that the bats’ sense of echolocation innate radar that detects obstacles – is confused by either, or both, the movement of the blades and/or the ultrasound they emit when doing so.
Or, then again, maybe it was a case of curiosity killing the bat.