Why migrating, tree-roosting bats are more susceptible to being killed by wind turbines has been a mystery. In a recent issue of the Proceedings of the National Academies of Science (PNAS), US Geological Survey scientist Paul Cryan offers an explanation: under certain wind conditions, the air currents around turbines is similar enough to the air currents around trees to confuse the bats into thinking the turbines are big trees.
The paper says that the bats congregate on the downwind side of trees to feast on the flying insects that congregate there. The paper doesn’t make this comparison, but it’s a lot like trout hanging out in an eddy, waiting for insects and other edibles to join them.
The problem, of course, is that spinning blades and barotrauma are not kind to bats that hang around wind turbines.
Two of the take-aways from the paper are that turbine operators can put bat deterrents on the downwind side of the turbines, and that changing the operating parameters of the turbines could help save bats, such as preventing the blades from turning in a sudden gust on an otherwise calm night.
Photo: Instead of going with a generic bat photo, since I don’t seem to have any of common migrating bats, I went with a generic wind farm photo. This is not the wind farm that was studied in the Cryan paper. Lovely photo by by Joshua Winchell.
As the second state struck by white nose syndrome in bats, good news for Vermont’s bats is good news for all hibernating bats in North America. An Associated Press story reports that scientists are interpreting results of a winter-long study of bat movements in New England’s largest bat hibernation site as showing a sharp reduction in the number of bats felled by white nose syndrome.
The scientists tagged over 400 bats, and found that only eight left their hibernation cave early. Only 192 bats left the cave at their normal time, but the scientists say they think those other 200 or so bats hibernated in another cave, as opposed to dieing somewhere deep in the cave out of reach of their tracking antenna.
A paper in the recent issue of The Journal of Wildlife Management says that Indiana bats can survive in areas with a high percentage of agricultural land, but that they strongly prefer both wooded and riparian areas. The paper says that they will fly more than a kilometer over open farm fields to reach a wooded area.
How small of a forest is too small for Indiana bats? The paper doesn’t cover that question, but it does raise the issue.
The Indiana bat is federally endangered species that is also threatened by white nose syndrome.
After the Wallow Fire, Arizona’s largest wildfire, burned 538,000 acres, a half-dozen biologists lead by Northern Arizona University researchers came in to study bats’ reaction to the changed ecosystem, an article in Bats Magazine, the magazine of Bat Conservation International, says.
It was no surprise that the team found that bats prefer unburned habitat to burned habitat. It was a little surprising that while bats generally avoided burned over areas, they would roost in burned snags. How burned a particular tree is compared to the other trees in the area seems to play a role in which burned snags are chosen as roosts.
Recording bats’ echolocation “calls” is the most efficient and least intrusive way of identifying different species of bats in a given area, providing insight into some populations that have been decimated by white-nose syndrome.This new research by scientists from Virginia Tech, the U.S. Geological Survey and the U.S. Army is published in the Journal of Ecology and the Natural Environment.
White-nose syndrome, an unprecedented disease of cave hibernating bats caused by a cold-loving fungus, has caused the deaths of more than six million bats. It has spread from central New York to at least 22 states and five Canadian provinces since 2006. In addition to the endangered Indiana bat, populations of the formerly abundant little brown bat and northern long-eared bat have experienced severe disease-related declines, particularly in the Northeast and central Appalachians.
“Acoustic sampling is a noninvasive sampling technique for bats, and its use often allows for the detection of a greater number of bat species in less time than traditional sampling methods such as netting,” said study co-author W. Mark Ford, a USGS scientist at the Virginia Cooperative Fish and Wildlife Research Unit at Virginia Tech. “Low population numbers make netting both time and cost prohibitive. Netting also has low capture rates for WNS affected species. Moreover, acoustic sampling minimizes the handling of bats, which lessens the chance of unintended cross-contamination and exposure to the white-nose fungus from one bat to another or from equipment and personnel to uninfected bats.”
After detecting the fungus that causes white nose syndrome, but not seeing any bats with the disease, for two winters in a row, dead bats showing the symptoms caused by the white nose syndrome fungus were found in an Arkansas cave on January 11, an Arkansas Game and Fish Commission (AGFC) press release says.
A total of five dead bats were found during a survey of the Marion County cave. Two of the bats were collected and submitted to the U.S. Geological Survey National Wildlife Health Center where it was confirmed that both bats had the fungus. Both bats had damage to wing, ear and tail membranes consistent with white-nose syndrome, the press release says.
This makes Arkansas the 23rd state to confirm white nose syndrome in bats.
Sorry for the double dose of white nose syndrome (WNS) news, but I didn’t want this to get lost in yesterday’s post on the the new WNS protocol, even though it was included in the same Wildlife Health Bulletin. Here’s the announcement:
In December, WNS was confirmed in a tri-colored bat (Perimyotis subflavus) from Jackson County, Missouri, which borders Kansas. This detection represents the western-most location of WNS in North America and is also the first detection of WNS during winter 2013/2014. The nearest confirmed cases of WNS from the previous winter are located in east-central Missouri.
The National Wildlife Health Center (in Madison, Wisc., part of the US Geological Survey) has updated the Bat Submission Guidelines for the 2013/2014 white nose syndrome (WNS) surveillance season.These are the protocols that you, a state wildlife biologist, would use to submit a bat or other sample to the center for WNS diagnosis.
The new protocol breaks the country into three regions (WNS prevalent, some WNS, no WNS yet) and has slightly different procedures for each region. One new aspect is the availability of swab kits, so that whole dead bats don’t always have to be sent to the center.
The notice for the new protocol also include the advice not to survey for WNS before mid-winter. The fungus is typically not recognizable before mid-winter and the extra disturbance harms the bats.
And, if you are a state wildlife biologist, and you haven’t signed up for the National Wildlife Health Center’s Wildlife Health Bulletin, you should. It comes out as-needed, and that has never been more than once a month, usually much less. Here’s the link to back issues. Information for subscribing is in tiny print at the end of the bulletin.
True, all my Halloween decorations depict vampire bats flitting over bare trees, which shows a shocking disregard for true nature of vampire bat habitat. (Can you hear the geeky tongue-in-cheek in that sentence? Good.)
But is Halloween actually bad for bat conservation? As a wildlife conservation writer, I can tell you that my editors are always happy to have a bat story on Halloween, even when they may not be interested the rest of the year. I haven’t had the editor yet who is cheesy enough to require spookiness in that Halloween bat story.
– Ohio Department of Natural Resources is studying how and why bobcats have returned to the state, by tracking 21 collared bobcats, The Madison Press reports. Previous research showed that there are two distinct populations of bobcats in the state. DNA analysis showed that the bobcats in both populations are from Pennsylvania, West Virginia and Kentucky. Read more in The Madison Press, here.
– David “Doc Quack” Riensche, an East Bay Regional Park District biologist, has been studying western pond turtles in in the eastern foothills of Mount Diablo outside Clayton, California for three years, the San Francisco Chronicle reports. The study has collected information on where the turtles winter and lay eggs. Western pond turtles are the only turtle native to California, but they face competition from non-native turtle species. Read more in the San Francisco Chronicle, here.
– Nearly 100 research volunteers surveyed the Cherokee Nation in Oklahoma for bats for this year’s “Bat Blitz,” organized by the Southeastern Bat Diversity Network, the Catoosa Times reports. One of the goals of the blitz is to document bat diversity before white nose syndrome harms bat populations in Oklahoma. Read more in the Catoosa Times.
Photo: This bobcat was in New York State. Photo courtesy NYS DEC