Three years of testing at wind energy sites throughout the state shows approximately 25 bats and four birds are killed every year at each of the state’s 420 active turbines, according to a report released by the Pennsylvania Games Commission.
That puts the estimated kills through June 2010 at some 10,500 bats and 1,680 birds. “The biggest challenge we have now is trying to get a hold of what acceptable (mortality) is,” Tracey Librandi Mumma, a supervisory wildlife biologist for the commission, said.
“The goal is we have to come up with that magical number. How many bats are too many? How many birds are too many? And then we go from there. This issue is bigger than Pennsylvania. Many states are dealing with this problem.”
“We don’t really have a good population estimate on bats, so 25 bats per turbine per year seems like a lot, and if you do the math with all of the turbines we have – and how many are proposed – it’s a huge number. But whether that number will impact the population is something we’re wrestling with right now,” she said.
The study is the first broad public release of information of data gathered through 2007’s Wind Energy Voluntary Cooperation Agreement between the commission and wind developers.
Approximately 30 participating developers agreed to conduct one year of pre-construction and two years of post-construction monitoring of birds and bats at each site using commission data-collection and study guidelines.
While the commission and developers tout the agreement as a successful partnership of science and industry, critics have questioned aspects of the data collection including methodology, the lack of peer review and severely restricted access to data collected at individual sites.
Scientists like Michael Gannon, a professor of biology at the Pennsylvania State University of Altoona and a recognized bat expert, have reservations about the report.
“One of my chief concerns is that they’re keeping their (raw) data very secret. Does the data support their conclusions? If you can’t review something it’s not science,” he said. “You just don’t know. It might turn out we get a look at these studies and end up saying, ‘look, they’re doing a good job, there’s no fear here.’”
Librandi Mumma acknowledged the privacy aspect and defended the overall study results. “The cooperative agreement we have has a confidentiality clause in it. Once they sign in, all their specific information becomes private. But we’re relying on the cooperators to fund and conduct these surveys. We definitely do not have the staffing or the funding to take this on ourselves,” she said.
The report shares some of the struggles and successes the commission has had in bringing developers to the table and refining their data collection in a way they hope independent scientists can eventually benefit from.
The agreement has helped several independent researchers in ways like sending turbine-killed bat remains to a rabies study conducted at the Center for Disease Control in Atlanta, Librandi Mumma said.
Right now 63 of the 86 proposed or active turbine projects across the state are signed into the agreement. Of those projects, 19 were already active or under construction, meaning developers only have to conduct the post-construction mortality studies, according to the report.
Florida Light & Power Energy’s subsidiary, NextEra Energy Resources, has five active projects and is the largest non-cooperating developer.
“We actively pursue all developers that are not cooperators,” Librandi Mumma said. “We try to keep our finger on the pulse of what new projects are out there. Several letters to several developers recently including Florida Light & Power,” she said.
The commission now considers that 31 of the 86 projects have a high risk of bat mortality. For birds, the number of projects labeled high risk is 15, according to the report.
The commission said that they have recorded no post-construction eagle deaths (including the threatened bald eagle and golden eagle) and in total have found only three endangered birds killed during the surveys.
The birds (all found in September 2009) included two blackpoll warblers and one yellow-bellied flycatcher. All three were considered to be migrants, according to the report. Two endangered Seminole bats carcasses were also found during the study. Those bats were believed to be migrating also.
Gannon said that his concern is that the mortality studies are flawed.
“Looking at what we do know about how those mortality studies are conducted, I think the number is low. Endangered species are exactly that. So finding them (in a site study) is already like finding a needle in a haystack. Losing one per week is an incredible impact,” he said.
In fact, the commission’s report states that all mortality estimates should be taken as a minimum number of those likely killed.
Both sides are increasingly concerned about bat populations because of a new disease spreading rapidly through populations across the country.
“Right now white nose syndrome is a greater concern to bat populations than turbines,” commission spokesman Jerry Feaser said. “When you have a hibernaculae of 5,000 bats with 90 percent or more (dying from the disease), the mortalities from wind turbines kind of pales in comparison.”
Gannon said that white nose syndrome is characterized by a distinctive fungal growth around the muzzles and on the wings of the affected animals and was likely introduced to North American bat populations (which have no immunity to the disease) by contaminated cavers visiting from Europe.
“This is just one of the reasons we want to have access to all the data. Bats are facing an incredible threat right now. Bats play a larger role in maintaining our ecosystem than most people realize. They are a keystone species. If you pull them out the consequences are likely to be severe,” he said.
Reducing bat kills at turbine sites could be achieved by raising the minimum wind speed operators have for starting the blades turning, the report said. Up to 80 percent of bat deaths occur when the blades are turning in wind blowing between 3.5 to 4 mph.
“There’s been very limited studies, but all the studies seem to show that this is a viable option to reduce that mortality,” Librandi Mumma said. If further studies bear out the early results, the commission could ask developers to refrain from starting the blades when the wind is below 5 mph, she said.
According to the study, the majority of bats are likely killed by the change in air pressure as the blade swings by a flying bat creating a massive embolism. “It’s a pressure issue, basically the capillaries in the lungs will explode,” she said.
However, any reduction of cut-in speed will not come until a number of studies are completed, Librandi Mumma said.
“But this is why we have this agreement. I definitely think it’s working and we’re able to make some good management decisions and we’re able to look at the entire state and see what’s going on in the wind energy industry and what the impacts are,” she said.
To read the complete report visit www.portal.state.pa.us/portal/server.pt?open=514&objID=613068&mode=2 online and click on the link for “PGC 2nd Wind Energy Summary Report.”