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A new bat in town

Southeast researchers are just beginning to understand how these local mammals live and where

Posted: November 1, 2013 - 12:02am
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Little Brown Bats are the most commonly detected species of bats in Southeast. In the eastern US, they've been hard-hit by white-nose syndrome.        Courtesy of the Alaska Department of Fish and Game
Courtesy of the Alaska Department of Fish and Game
Little Brown Bats are the most commonly detected species of bats in Southeast. In the eastern US, they've been hard-hit by white-nose syndrome.

There’s a new (known) bat in Southeast.

For the last three years, researchers at the Alaska Department of Fish and Game have been researching the little known bats of Southeast Alaska. At this week’s “Wildlife Wednesday,” hosted by the Southeast Chapter of the Alaska Wildlife Alliance, Alaska Department of Fish and Game Regional Wildlife Biologist Karen Blejwas spoke on what they’ve learned so far.

Up until recently, researchers in Western states “by and large have neglected” bats, she said.

In 2006, white-nose syndrome, a fungus affecting and killing hibernating bats, began spreading across eastern North America. One of the hardest-hit is the Little Brown Bat, Southeast Alaska’s most common species.

White-nose syndrome hasn’t yet been detected in Alaska, but the disease’s spread has been a “wake-up call” for western biologists, Blejwas said.

“We stand the chance of losing bats before we really even know what we have,” Blejwas said.

ADF&G biologists and wildlife technicians, and partners across Southeast, have completed research over the last three years that has begun to sketch in some of that missing information.

Bats, the only mammals that have evolved powered flight, are more closely related to primates than rodents. All of Southeast Alaska’s species are insectivorous and use echolocation to hunt, detecting the shape, size, texture, distance and movement of objects within a short range, Blejwas said.

Researchers have used acoustic monitoring to detect and record echolocation calls — technology that has “revolutionized” the study of bats, helping to fill in information about their presence, distribution, seasonal patterns and activity.

Previously, the five kinds of bats known in Southeast Alaska were the Keen’s Myotis, the Little Brown Bat, the Silver-haired Bat, the Long-legged Myotis, and the California Myotis. (Big Brown Bats’ calls are similar to those of the Silver-haired Bat, and though Blejwas said it’s possible some of the calls they detected were Big Brown Bat calls, it’s not probable.) The new bat, making six known bats in Southeast Alaska, is the Hoary Bat.

Researchers discovered that California Myotis’ range extends farther north than previously known; they detected it at all of their monitoring stations.

Keen’s Myotis has the smallest range of any bat in North America. They also detected this species farther north than previously known.

They didn’t learn anything new about the Long-legged Myotis; it hasn’t been detected as far north as Juneau, Blejwas said.

The Silver-haired bat is only known from four specimens in Southeast, she said — all female, all in winter and all in or near people’s homes. It has been acoustically detected across most of Southeast Alaska, though 90 percent of the calls they detected were at Hugh Smith Lake in Misty Fjords National Monument, a place they’d like to do more research, Blejwas said.

The Hoary Bat was detected using acoustic monitoring in downtown Juneau and Auke Lake, as well as in Gustavus, Hoonah and Ketchikan. It’s one of the most widely spread bats in North America, detected in every other state, but hadn’t previously been detected in Alaska.

Bat activity begins picking up around early April in sites like Cowee Meadow and the Mendenhall Valley in Juneau. By early June, monitors detect activity at most sites. Female bats begin lactating around summer solstice and continue through the beginning of August, and researchers detected juveniles from mid-July until late September.

Bat activity begins to taper off toward the end of September and early October. By mid-October, there is very little.

It was only this year that researchers discovered where some of the bats are going.

In eastern North America, bats tend to hibernate in caves, in large numbers. While some maternity roosts in Juneau have large numbers of bats — one maternity roost in the Mendenhall Valley, notably, had about 1,000 bats — they tend to hibernate differently.

“Bats really do seem to be doing something different in the West,” Blejwas said. “They’re not aggregating.”

The first two years researchers tagged Little Brown Bats and tracked them, they were frustrated by losing radio signals in cloud banks around Admiralty Island. This year, they discovered that part of the reason they were having difficulty tracking signals is because bats were hibernating in rocky underground crevices.

Wildlife Biologist Michael Kohan, who successfully tracked the first bat to its underground roost, said it didn’t emerge as long as the tag was functional (because the tags are so small, they last only a short while.)

Blejwas said though she’s spoken to dozens of people who have built bat houses, she doesn’t know of anyone who’s had a bat take up residence there. ADF&G hopes to partner with the University of Alaska Southeast Construction Technology Program to develop improved heated bat houses.

“We don’t know what works yet,” she said.

The research project was funded by a USFWS State Wildlife Grant. Blejwas anticipates one more field season in which she hopes to learn more about the difference between the calls of northern bats and those farther south, getting a large enough repository of calls to make acoustic monitoring in Southeast Alaska more reliable. If possible, she’d like to partner with others to continue monitoring the bats past the next field season.

• Contact reporter Mary Catharine Martin at maryc.martin@juneauempire.com.

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