Big effort to better understand bats begins
There is an effort to better understand the ecological role that bats play. It spans 31 states and 10 Canadian provinces. The effort also looks to better understand the threats bats face from climate change. Bats also face threats from habitat loss. And from wind energy development.
The North American Bat Monitoring Program has acoustic surveys. The surveys find the high-pitched frequencies given off by the flying mammals as they catch bugs and find their way in the dark.
"It is long overdue," said Patty Stevens. She is the U.S. Geological Survey's branch chief for Trust Species and Habitats. The branch is at the Fort Collins Science Center in Colorado. That is where the program's data will be stored and made available. "It is going to provide a lot of information to natural resource managers."
The monitoring program has been driven by a disease called white-nose syndrome. The disease has killed millions of bats. And the disease is spreading.
North America has some 150 species of bats. Forty-seven of them are in the United States. Some migrate more than 500 miles. Others hibernate in caves or abandoned mines. Less than a handful of bat species are well understood.
"Most of our bats are very small. They fly at night. They are very difficult to study," said Susan Loeb. She is a research ecologist with the U.S. Forest Service. It is based in Clemson, South Carolina. "In the last 10 to 20 years, we are getting better and better technology. It allows us to learn about bats."
Acoustic monitoring of bats is one example. At one time it meant carrying equipment on a vehicle. Now a device can be hooked up to an iPhone. Scientists are also trying to perfect software that can identify the species of bat making the sound.
Loeb is the lead author of the U.S. Department of Agriculture's Plan for the North American Bat Monitoring Program. The plan set out the first strategy.
The plan relies heavily on acoustic monitoring. This includes both mobile monitoring sites and stationary sites. The number of sites varies by state as the program gets going. Idaho got off to a tough start this year. Giant wildfires slowed efforts at about 10 sites.
Researchers are using other methods as well. These include counting hibernating bats in winter. And doing maternity colony counts in summer.
In five years researchers should have enough information to spot trends.
"We know that many bat populations are declining. But we do not know the magnitude of that decline," Loeb said.
Information like that is important. Bats are thought to be a key part of forest health. This is due to their diet of insects.
There is not much information on bat insect feeding. But scientists have a guess on the Brazilian free-tailed bat colonies in Texas. They think they can eat more than 8 tons of insects in a night. They often number more than a million.
Most North American bats eat insects. But there are some nectar-feeding bats. They help pollinate plants. The iconic saguaro cactus in Arizona is one example. It is pollinated by the lesser long-nosed bat. And also the Mexican long-tongued bat.
A more recent threat to bat are wind farms. An estimated 200,000 to 800,000 bats die annually in collisions with spinning blades.
"We still do not know why bats are getting killed by these turbines," said Loeb. "Why can't they detect them? Are they attracted? And how do we deter them?"
Scientists are trying to figure that out. Loeb said clues might be found in the bat monitoring program.
Scientists are also working to raise awareness of bats. They are organizing much of those efforts leading up to Halloween with National Bat Week. Loeb herself is spending part of the week at a meeting of The North American Society for Bat Research.
"Using Halloween as a means to engage people that bats are not bad may be one way to do it," Loeb said. "The public perception of bats is changing as people learn how important they are and how fascinating they are."