Friday, June 05, 2015

Driving Really Slow….

by Marilynne Manguba Idaho protection specialist  

Did you know that most vehicle cruise controls don’t work under 25 mph?   A group of citizen scientists figured this out last summer and fall when they participated in mobile acoustic surveys to gather basic information on bat ecology and population dynamics.  

A few years ago, I attended a presentation on bats in eastern Idaho.   Bat ecologist, Bill Doering, talked about discovering tree bats that were migrating across the desert.  Big surprises for me: that bats roost in trees, and they migrate across the “Big Desert” in eastern Idaho. So in 2013 when the Idaho Department of Fish and Game asked for volunteers to conduct surveys of bats in eastern Idaho, I just had to know more.  

Unidentified bat species in Formation Cave © Marilynne Manguba

Why study bats?   One of the most common bats in the United States, the little brown bat, weighs between 5 and 14 grams and can eat 4 to 8 grams of insects a night.  Studies estimate that the loss of one million little brown bats in the northeast has resulted in over 650 metric tons of insects no longer being eaten each year by bats.  That’s quite an impact on agriculture and that’s only one bat species in one location in the northeastern US, so imagine what that might mean in eastern Idaho.   

White-Nose Syndrome, a fungal infection that has killed almost 6 million bats, has spread as far west as Iowa since its discovery in New York state in 2006 and has been found in 26 states and five Canadian provinces.  Recently, 150 bats infected with White Nose Syndrome were successfully treated and released as a result of research supported by the Tennessee Chapter of The Nature Conservancy. Read that story here.  

Bats with White-Nose Syndrome © Dave Riggs/Flickr

So far, White-Nose Syndrome has not spread into Idaho, but since we don’t have much information on bat populations, we’re at a disadvantage when it comes to preventing the spread of White-Nose Syndrome and understanding other impacts to populations of resident and migrating bats.

This is where driving really slow comes in.  Each volunteer team is assigned a route. Routes include one in the Bear River area, near Formation Springs where the bat in the photo above was found, several around the Flat Ranch Preserve in Island Park and Medicine Lodge, near our Crooked Creek Preserve. A broadband high-frequency microphone hooked up to a bat detector that records bat echolocation calls is mounted on top of a vehicle. Then just after sundown, the team drives the assigned route at 20 mph.  

As you drive, the detector picks up the sounds of bats flying overhead.  Bat calls are very distinctive and you can sometimes hear the change in their call as the bat approaches their flying dinner.  In 2014, teams drove over 1100 miles recording calls.  Ten species of bats were identified from their unique calls.

Big-eared bat © John C.

Last year, Idaho Master Naturalist Pegge Steele and I drove 24 miles from Sage Junction near Hamer, between the twin Menan Buttes to the Snake River. We repeated that drive once a month from June through October and recorded 45 calls from five different bat species. Species we recorded included the Western small-footed myotis. Generally found around rock outcrops and open grasslands, they feed early in the evening on small flying insects and are known to hibernate in lava tube caves on the Snake River plain in eastern Idaho. The Silver-haired bat, a long-distance migrant common in old growth Montane forests can be found roosting in cavities of trees or under loose bark. They are believed to be one of the slowest flying bats in North America.   

View across the desert to Menan Buttes at sundown © Marilynne Manguba

The biologists running the study spent the winter analyzing signals, acquiring upgrades to the equipment and tweaking the process. In May, we started our slow drives across the high desert again.  As more information is collected about bat species, preferred habitat, and migration corridors, scientists hope to be able to anticipate impacts from habitat changes, White-Nose Syndrome, and identify other threats to bat populations in eastern Idaho.   

Editor’s note: Bat conservation is important to people and places around the world. In the USA alone, bats contribute $3.7 billion to reduced crop damage and pesticide use every year.  Bats are critical pollinators and seed distributors for a wide variety of plants.

Learn more about bats by visiting TNC’s Cool Green Science blog.