In the field: Townsend’s big-eared bats in Colorado

Researcher holding a Townsend's big-eared bat. Photo credit: Ann Froschauer/USFW

While presenting at the 2011 National Speleological Society (NSS) Convention in Glenwood Springs, CO a few weeks ago, I joined bat researchers from USGS, National Park Service, USDA Forest Service and Colorado Parks and Wildlife Division working with Townsend’s big-eared bats (Corynorhinus townsendii) near Marble, Colorado.

The site was an abandoned mine, protected by a gate, and home to a maternity colony of over 700 Townsend’s big-eared bats. These bats are a state species of concern in Colorado and several other western states. I love big-eared bats, they are some of my favorites- I’ve worked with Rafinesque’s in the eastern United States, so this night was particularly exciting for me. Not only was I about to see my first western species, it was a big-eared bat to boot!

Researchers set up the mist net outside the maternity colony site (mine).

We hiked up to the mine site, gear in tow. Tonight the goal was to capture about 40 bats to which the researchers would apply pit tags. Just like the tiny devices for our pets that veterinarians can scan to help find a lost dog or cat’s home, the researchers hope that they will be able to scan hibernating bats this winter and determine where the bats from this specific maternity colony go to hibernate.

The research crew got busy setting up the mist net outside the maternity colony site, got their data sheets and supplies for pit tagging and decontamination between bats ready to go, and we all fended off mosquitos as the sun set over the beautiful Crystal River valley.

Wildlife technician removes Townsend's big-eared bat from mist net.

It wasn’t very long until bats started swirling around inside the gate and slipping between the bars and off into the night in search of small moths (the big-eared bats’ favorite) or the occasional beetle, fly or wasp. Suddenly the mist net was quivering.”We’ve got one!” one of the technicians whispered, and darted off to quickly remove the bat.

As she deftly untangled the tiny bat from the filament of the mist net, I snapped a few photos. Before long another bat hit the net. And another. The technicians worked quickly and quietly to remove the bats from the net, place them in soft cloth bags, and hand them off to the researchers working just down the hill.

Researcher inspects Townsend's big-eared bat. Photo credit: Ann Froschauer/USFWS

The researchers- including USGS Research Biologist Paul Cryan (one of the leading WNS researchers) and National Park Service Wildlife Veterinarian Kevin Castle start working up the bats. Gently removing them from their bags, they jot down a few notes and quickly insert the small pit tag under the skin on their back before placing them back in the bag for a few moments to recover before they are released.

This winter, when surveying known Townsend’s hibernacula, researchers will scan the bats with a handheld device to detect any pit tagged bats. This will help biologists develop a better understanding of these bats- where they go to hibernate in the winter before they return to the maternity roost high in the hills the following season to give birth and raise their single pup. Not much is known about the natural history of this bat, or many other bats for that matter. White-nose syndrome has thrust this dearth of knowledge about these unique mammals into the forefront. It’s now a race against time to figure out as much as we can about bats, like the Townsend’s big-eareds, before it is too late.

White-nose syndrome has not been detected in Colorado yet. An additional ray of hope- Virginia big-eared bats (a close cousin of the Townsend’s) do not seem to be suffering the same fate as other hibernating bat species in eastern North America when WNS arrives in their hibernacula. We remain hopeful that environmental conditions will slow the spread of the fungus and WNS to western states, and that some bat species (like the Virginia big-eareds in the east) will be less susceptible to this devastating disease.

Biologist releases bat. Photo credit: Ann Froschauer/USFWS

This night we needed to capture about 40 bats and insert pit tags. To me, coming from the Northeast and the epicenter of white-nose syndrome, this seemed a daunting task. I’ve been out on nights mist netting and feeling lucky to capture a few bats. Bats were still emerging from the site and hitting the net when a quick count netted 43 bats. Extra bats? My heart soared!

The technicians quickly pulled down the nets and freed the additional bats, “It’s your lucky night, little girls.”

To see more photos, please visit our WNS Flickr collection.