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Bringing Alaska's bats out from the shadows

  • Author: Rick Sinnott
  • Updated: February 19
  • Published February 19

Marian Snively holds a little brown bat caught in Delta Junction. (ADF&G photo)

American attitudes toward "historically stigmatized" animals — including bats — have grown more positive in the last three decades, according to research published last year in the journal Biological Conservation.

Nevertheless, most of us don't think about bats much, particularly in the middle of winter.

Theodore Roethke memorialized a close encounter with a bat in his poem "The Bat." Seeing one flutter against a screen door, he made the chilling observation that "we are afraid of what our eyes have seen: for something is amiss or out of place when mice with wings can wear a human face."

I've never seen a bat with a human face. But I can imagine Peter Haeussler's surprise when he came face to face with a bat in an unusual and unexpected place.

Haeussler is a research geologist with the U.S. Geological Survey in Alaska. On Oct. 21, 2008, he and a fellow geologist, Sue Karl, were looking for rock outcrops along Petersville Road. Geological fieldwork isn't normally conducted in winter, but they'd been swamped with work the previous summer.

"It had snowed," Haeussler recounted, "but there were still exposures we could examine."

The two scientists strolled up to an outcrop and, because geologists prefer to examine fresh rock surfaces, Haeussler says he "whacked" the rocky ledge with his 2-pound sledgehammer. A relatively large chunk, about the size of a football, broke off. That's when they saw the bat, snuggled into a crevice exposed by the blow.

Surprisingly, this was Haeussler's second close encounter with a bat. He recalled an earlier incident while rock climbing in central Michigan. He was about halfway up a 40-foot cliff when a brown piece of moss "turned its head, opened its mouth wide and hissed at me." Haeussler promptly fell off the cliff.

"So, when I saw this bat," Haeussler said, "I was glad it did not turn its head and hiss at me."

Bats in Alaska

Marian Snively, a biologist with the Alaska Department of Fish and Game, was understandably excited by Haeussler's discovery. Snively has been compiling information on Alaska bats for years.

Bats are common here, but scientists don't know much about them. For instance, Snively says there is still a lot of uncertainty regarding whether most of Alaska bats hibernate or migrate to more favorable climes. And if they hibernate, where are they?

It's known that bats overwinter in caves, but caves are uncommon in Alaska. They will also hibernate in mine shafts and buildings, particularly barns, sheds and cabins not frequented by humans. However, bats aren't ubiquitous in these settings. So where are they?

More than 40 bat species live in North America — and only six of them have been found in Alaska. Some species have been recorded only in Southeast Alaska, which may be the northern limit of their range.

The most common bat found throughout Alaska is the little brown bat. That's its official common name, not a generic description. Little brown bats inhabit forested areas across the state, with occasional sightings in Western Alaska.

About the weight of a quarter, the flying insectivore — despite what poets say, bats are not closely related to mice — remains one of the least-known mammals in Alaska, despite its widespread range. The little creatures are about 3 or 4 inches long, among the smallest mammals in the state, smaller than some of their distant cousins, the shrews.

White nose syndrome

About 115 species of wild mammals live in Alaska and surrounding waters. With the exception of those valued for their meat or fur, little is known of most species. That's understandable if the species isn't being managed for subsistence or sport hunting and trapping — or threatened with extinction. There will never be enough money to study and monitor every species in the state.

Unfortunately, bats are increasingly threatened by a deadly disease that strikes them where they are most vulnerable, in their hibernacula, the protected enclosures where they congregate during winter. The fungus is called white nose syndrome because it covers the nose and other parts of hibernating bats. Bats exhibiting white nose syndrome behave strangely, flying outside on cold winter days and clustering outside cave entrances.

The fungus was first documented in New York state in February 2006. It has since spread throughout most eastern and midwestern states and southern Canada. Last year white nose syndrome was found in a bat in Washington state.

The fungus is spread by contact when bats are clustered in hibernacula, where an unprecedented number of deaths have been documented. More than 5.7 million bats in eastern North America have succumbed in the past decade, sometimes 90 to 100 percent of the bats in a cave.

Reacting to the potentially global threat, in 2015 the United States signed a treaty with Canada and Mexico, a historic agreement to cooperate and coordinate bat conservation efforts that mirrors the Migratory Bird Treaty Act of 1918.

The disease's recent leap across the plains states into Washington has increased the stakes in Alaska. Not only do we not know where bats hibernate, we don't know much about their distribution and abundance during their active seasons. It's going to be difficult to know if white nose syndrome is decimating Alaska's bats if we don't have any idea how many bats we have.

Recognizing that shortcoming, Snively is also collecting data on bat distribution and relative abundance across the state in the non-winter months.

In 2014 Snively and two other colleagues summarized eight years of anecdotal information gleaned from volunteer observers. Their article in the journal Northwestern Naturalist noted bats were seen as far west as Kotzebue and White Mountain and, in the Interior, as far north as Fairbanks and Tok. The volunteers found 111 bat roosts, 97 percent of which were located in human structures.

Of course, these sightings were influenced largely by where people live, not necessarily where bats were hanging out. For example, the volunteers found no winter hibernacula in natural locations. They were all in human structures.

Bat surveys

Consequently, the researchers switched to more objective methods. Thanks to electronics, finding bats is easy, even when they aren't easily seen. Bats rely on sonar to "see" where they are going and to find prey. Their calls can be recorded on bat detectors.

Using a bat detector — which graphs the frequency and duration of the mostly ultrasonic calls — an expert can determine the number of bat calls at the location and even identify bat species because each species uses slightly different frequencies.

Snively and her colleague Karen Blejwas in Juneau have deployed several dozen bat detectors, and Blejwas conducts surveys in a vehicle to obtain a more accurate measure of relative population sizes.

Snively loaned me a bat detector last spring. I already knew bats visited my house because I see them in the evenings during the summer. What I didn't know was the species and how often they were in the vicinity.

I left the device up until late fall because Snively assured me that she often sees an uptick in numbers in September and has recorded bat chirps as late as November in Southcentral Alaska.

What we found was a little underwhelming. All of "my" bats appeared to be little brown bats, as I suspected. All of my bat visitors flew by in July and August. On most days only a handful of chirps were recorded. Some days a larger number of calls were recorded, but never more than 40 until the last three days of August when the number of calls spiked at about 130 in one night.

Bats don't broadcast sonar constantly when they fly. But they inevitably emit the high-frequency chirps when they are foraging for moths and other flying insects. Forty calls may represent a few passes by a couple of bats. In other words, my house is not a hot spot for Anchorage-area bats.

Snively wouldn't tell me where the local hot spot is, but she described it as a small pond in Chugiak where over 1,000 calls have been recorded in one day.

They may be everywhere

Before Haeussler found the bat in the crevice, Blejwas had found radio-collared bats in root wads and loose scree in Southeast Alaska. Snively was aware that bats also hibernate in tree crevices and loose bark. There are plenty of these microhabitats in Alaska, even though individual locations won't accommodate large groups of bats.

What these mostly anecdotal reports suggest is that — despite Alaska's relative paucity of caves, mining shafts and abandoned buildings — there seems to be plenty of places for bats to hibernate, either alone or in small groups. It's not that wintering bats are here or there; they may be everywhere.

The limiting factor — lack of large spaces for hibernacula — that compels Alaska's bats to hibernate alone or in small groups may be their salvation. White nose syndrome is spread by contact, and not having any bunkmates, while lonely, may prevent or at least curtail the spread of the disease in Alaska.

Rick Sinnott is a former Alaska Department of Fish and Game wildlife biologist. The views expressed here are the writer's own and are not necessarily endorsed by Alaska Dispatch News. Contact him at rickjsinnott@gmail.com.

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