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Southern Alberta wind farms have been providing families and businesses with electricity created by the wind, but also have been endangering wildlife.
It has been estimated thousands of bats have been killed due to wind farms each year in southern Alberta alone.
Dr. Robert M.R Barclay, a professor and department head of the department of Biological Sciences at the University of Calgary, says bats are mainly being killed when they get hit by the turbine blades that are moving.
“Those blades are moving fast (about 200 km per hour at the tips). Some bats are killed when they get close to the blades and fly through a zone of low air pressure. This causes the air in their lungs to expand rapidly causing internal damage, much in the way that a scuba diver who comes up too fast experiences problems,” says Dr. Barclay in an e-mail interview.
“At another level, we don’t really know yet why the bats are so close to the turbines. Most of the bats killed are migrating south for the winter and we see all across North America, a large peak in fatalities in late summer and early fall. In Alberta, this involves two main species, the silver-haired bat and the hoary bat. These spend their days in trees. So some scientists hypothesize that the bats see wind turbines as giant trees that may provide suitable roosts for the day, and the bats thus approach them. Others suggest that insects are attracted to the turbines and bats, which in Canada eat nothing but insects, are attracted to the swarms of insects. Yet another suggestion is that the migrating bats mate during their southward migration and to find each other, males and females congregate at tall trees.”
Dr. Barclay explains the first large incident of fatalities of bats at wind farm facilities occurred in 2003 at a site in West Virginia. Before that, the focus was on bird fatalities.
Bat fatalities still occur due to coming in contact with wind farms. However, the bat fatalities have been much higher across North America.
Dr. Barclay says this has seemed to be related to the fact early turbines were quite short and therefore the blades were as high as the migrating bats fly. As turbines have gotten larger, the fatalities of bats have increased. Now, across Canada, Dr. Barclay says about 10 times more bats are killed than birds.
He adds the first evidence of relatively large bat fatalities at Alberta wind facilities was in 2005.
As the total number of turbines increase, so does the number of bat fatalities.
In 2005, Barclay was approached by one of the main wind energy companies in Alberta and that’s when he decided to begin his research. He says the company was called Vision Quest at the time, but is now part
of TransAlta. Barclay continues to work closely with them and other companies to try and reduce bat fatalities.
There are several things that need to be done and can be done to reduce the number of bat fatalities from contact with wind farms.
“I believe we need two major things. First, there are ways to reduce fatalities at turbines, as I describe below, and although some companies (TransAlta for example) have adopted some of these measures and in doing so have reduced fatalities considerably, we need more companies to implement these actions,” explains Barclay. “Second, we need better understanding of the basic biology of the species that are being killed. We need to determine how many of these bats there are and what effect on their populations the additional mortality caused by turbines (and other human-caused issues such as habitat loss and climate change) is having. We need to know whether there are separate, identifiable populations of each species and what routes those individuals travel during their migration so we can assess how many wind facilities they encounter on their travels and thus what the cumulative fatality rate is, not just at one wind facility in southern Alberta, for example, but along the entire migratory route.”
During his research, Barclay says while his students were picking up dead bats underneath wind turbines, they found very few birds. He says most studies at other sites across North America have similar findings.
Barclay says there are two ways to keep fatalities of bats to a minimum. The first is to build wind facilities where there are fewer bats, especially migrating ones. Bats tend to migrate through areas with more trees, such as along the foothills.
The second strategy is once a site is built, there are ways to operate the turbines during the migration season so that fewer bats are killed.
“In our research, we showed that bat fatalities can be reduced by changing how the turbines operate at night during the migration season (about a six-week period in late summer and early fall). Bats in Canada are small (the largest weighs about as much as four loonies), so they don’t like to fly when it is very windy. (It’s too hard to do). Thus many studies have shown that most of the bat fatalities happen when the wind is relatively slow,” says Barclay. “Thus, preventing turbine blades from turning when the wind is low, reduces fatalities significantly, while not costing that much in terms of energy production or revenue. Our experiment with TransAlta reduced bat fatalities by over 50 per cent, and later studies elsewhere have found similar results.”
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