8 SEPTEMBER—OCTOBER 2016

A Spreading Mystery

Story by Dana Michaels

Imagine being awakened from a deep sleep by a persistent, irritating itch in your skin. Your body is cold, so your muscles and other tissues burn energy reserves to warm up. You’re hungry. Searching for food and finding none, your energy wanes. You can

barely lift your arms and you fall to the ground, exhausted and starving. That may be similar to what hibernating bats feel when white-nose syndrome (WNS) strikes them. The disease has killed more than 6 million bats in the eastern half of North America, and now threatens bat popula-tions in the West.

WNS is caused by the fungus Pseudogymno-ascus destructans, which grows in and on bats’ skin during winter hibernation. In some cases it gives them a white, fuzzy appearance on the muzzle, wings and ears. The fungus invades deep skin tis-sues and causes extensive damage. Affected bats awaken more often than normal during hiberna-tion and burn up the fat reserves they’ve stored to survive the winter. Most bats in North America are insectivores, and there are few insects on which to feed in winter, so affected bats either starve or freeze to death. The wing damage can also cause problems with physiological processes such as blood circulation, the bat’s ability to regulate body temperature and, of course, flight. Impairment of any of these processes leads to death.

Scientists believe Pseudogymnoascus destruc-tans was introduced inadvertently from Europe, where it is now believed to have occurred for so long that native bat species have evolved over many generations to have resistance to it.

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Deadly bat fungus takes a giant leap as white-nose syndrome moves from the East Coast and reaches the West

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OUTDOOR CALIFORNIA 9OUTDOOR CALIFORNIA 9Photo courtesy Ann Froschauer/U.S. Fish and Wildlife Service

Opposite page, Western States bat species—such as this pair of little brown myotis—have one advantage over bats in the eastern portion of the country as they tend to hibernate in smaller groups, making the spread of white-nose syndrome less likely. This page: At dusk in the Hill Country of central Texas, thousands of Mexican free-tailed bats soar from the depth of their cavernous home in a swirling mass seeking flying insects. In hopes of better understanding bat species and the deadly fungus, researchers study roosting populations, like the one found within this Texas cave.

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First discovered in the United States in late 2006 near Albany, New York, the fungus quickly spread throughout the eastern and midwestern states and eastern Canada. Its effect was devastating as it wiped out or drastically reduced many bat colonies to tiny remnants of their former numbers. By 2016 it was in 29 states and five Canadian provinces.

To curb the spread, the U.S. Fish and Wildlife Service and partner agencies in state and federal governments launched a national response effort. Because of the nature of the fungus and the swiftness that it moved from one colony to another without regard to geopolitical borders, any effective effort would have to be large-scaled and organized for cooperation between federal, state, local, tribal and non-governmental organizations, including the bat conservation and caving communities. The U.S. Fish and Wildlife Service (USFWS) leads the national response team that includes experts from the U.S. Forest Service (USFS), U.S. Geologi-cal Survey (USGS) National Wildlife Health Center, National Park Service, Bat Conservation International and the National Speleo-logical Society.

Since California is home to 25 species of bats, the threat of

WNS concerns state environmental scientists and wildlife manag-ers. Two species found here—the big brown bat (Eptesicus fuscus) and little brown bat (Myotis lucifugus)—have succumbed to WNS in other states. Silver-haired bats (Lasionycteris noctivagans) have been found with the fungal spores and other tissues on them, but with no apparent WNS symptoms. There’s a good chance non-hi-bernating species like the hoary bat, silver-haired bat, California leaf-nosed bat and red bat would not be affected.

Until last spring the westernmost occurrence of WNS was in eastern Nebraska. Anticipating the fungus would continue to move incrementally westward, the USFWS assigned a WNS coordinator in each of its eight regions to orchestrate state and regional operations. It also launched a web page for detailed infor-mation at www.WhiteNoseSyndrome.org.

Then, earlier this year, plans for slowing the spread of the fungus suffered a setback. In March, hikers found a little brown bat with the symptoms of WNS near North Bend, Washington. The discovery caught the WNS community by surprise. The fun-gus may have spread undetected by bat-to-bat contact across the Great Plains and Rocky Mountains, but researchers and wildlife

Photo courtesy Ryan von Linden / New York Department of Environmental Conservation

A close-up of the nose of an infected little brown bat in New York shows how the Pseudogymnoascus destructans fungus appears on the victims. First found in a New York bat colony in 2006, white-nose syndrome has spread to 29 East Coast and Midwest states as well as five Canadian provinces. Over the decades, countless bat colonies have fallen victim to its deadly fungus.

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managers speculate that it was probably carried west by some-one whose clothing or gear was contaminated, perhaps while exploring caves in eastern states. There were no documented cases of the syndrome in the nearly 1,300 mile expanse between the last site in Nebraska and newest in Washington. Genetics tests of the fungus found in Washington confirm that the strain is of North American, not Eurasian, origin.

Why Should We Care About BatsBats are nature’s best pesticide. According to a study by the

University of California, Division of Agriculture and Natural Resources, each of these small mammals eats between half and 100 percent of its own weight in insects every night. Some California species consume as many as 600 insects per hour. Imagine living with all the mosquitoes, flies, midges, moths and agricultural pests that are now consumed by bats!

In monetary terms, the natural pest control that bats pro-vide is extremely valuable to the state’s $54 billion per year ag-riculture and $450 million timber industries. The bats’ appetite reduces the need for chemical pesticides, reduces crop losses and

curtails the spread of crop diseases. According to the USGS, a recent economic analysis indicated that insect suppression services provided by bats to U.S. agriculture is valued between $4 billion and $50 billion per year.

Fringed myotis* PSSC, SCCave myotis* SSC, SCLong-legged myotis* PSSC, SCYuma myotis* SCCanyon bat* Western pipistrelle

Family Phyllostomidae (leaf-nosed bats)Mexican long-tongued bat SSC, SCLesser long-nosed bat FECalifornia leaf-nosed bat SSC, SC

Family Molossidae (free-tailed bats)Western mastiff bat SSC, SCPocketed free-tailed bat SSCBig free-tailed bat SSC, SCMexican (Brazilian) free-tailed bat

Big and little brown bats have shown symptoms of WNS in other states. Silver-haired bats have tested Pseudogymnoascus destructans positive, but no diag-nostic sign of WNS has been documented.

*Hibernates long enough to be affected by WNS.

CDFW senior environmental scientist Scott Osborn notes the estimate’s wide range makes it hard to know exactly how much money bats save farmers. “But even the low estimate, $4 billion, is an impressive amount,” he said. “Bats are an important part of integrated pest management systems.”

California’s bats are so valuable to viticulture that their role as pest-controllers in vineyard ecosystems has been formally recognized by the wine growing industry and listed as part of the California Sustainable Winegrowing Practices programs and the Lodi Rules for Sustainable Winegrowing. Mexican free-tailed bats (Tadarida brasiliensis)—common in Northern California’s grape-growing regions—are likely to eat as many as seven grape-specific pests.

When Caltrans rebuilt the old Franklin Boulevard Bridge over the Mokelumne River and floodplain, just north of Lodi vineyards, they used an underside design that included roost-ing crevices so the large bat colony living under the old bridge wouldn’t be displaced. A recent survey of that colony estimated its population to be approximately 60,000 strong—the same as before construction began.

An added bonus in this project was cited in California Bat Mitigation Techniques, Solutions, and Effectiveness, a 2004 report prepared for Caltrans by H.T. Harvey & Associates and bat biolo-gist Dave Johnston. The report praised the mitigation strategies and noted that the cast-in-place concrete with bat roosts saved $200,000 off the original $9.2 million cost projection.

“This bridge project demonstrates how a cooperative com-

California’s 25 Bat Species

Common Name Status

Family Vespertilionidae (mouse-eared bats)Pallid bat* FSS, SSC, SCTownsend’s big-eared bat* FSS, SSC, SCBig brown bat* Spotted bat SSC, SCSilver haired bat* Western red bat* FSS, PSSCHoary bat* Western yellow bat PSSC, SCCalifornia myotis* Small-footed myotis* SCLong-eared myotis* SCLittle brown myotis* Arizona myotis SSC, SC

Legal Status:FE = Federally EndangeredFSS = USDA Forest Service SensitiveSSC = CDFW Mammal Species of Special ConcernPSSC = Proposed CDFW Mammal Species of Special Concern

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Signs of White-nose Syndrome• White or gray powdery fungus seen around the muzzle, ears,

wings, limbs or tail of bats

• Bats on the ground (either inside or outside a hibernation roost), roosting near the entrance to or increased bat activity outside a hibernation roost, or premature return to a summer roost during freezing weather

• Thin body condition or dehydrated appearance of a dead bat (wrinkled and flaky appearance of furless areas)

• Wing damage, including membrane thinning, depigmentation, stickiness, holes, tears or flaky appearance on bats that are found outside of a hibernation roost or at a summer roost

• Bats exhibiting yellow-orange fluorescence on hairless skin under long-wave ultraviolet lighting

• Excessive or unexplained mortality or population decline at a winter hibernation roost

Help Prevent the Spread of WNS• Report any bats that show signs consistent with white-nose

syndrome or if any bats are seen flying during extremely cold or freezing temperatures. For information on WNS, refer to the California Department of Fish and Wildlife’s online reporting form (www.wildlife.ca.gov/Conservation/Laboratories/Wildlife- Investigations/Monitoring/WNS/Report)

• Do not handle live bats—they bite and can carry rabies

• Avoid entering caves, mines or other areas used by bats to avoid disturbing them and potentially spreading the disease to unaffected areas

• If a cave, mine or bat roost is entered, be sure to decontaminate all equipment and clothing immediately after exiting. Do not bring dogs or other pets in caves, as they may act as carriers of the fungus to new sites

munity of environmental planners, engineers and biologists can work together to plan and implement outstanding, successful mitigation strategies for large numbers of bats.”

Even bats’ waste is valuable. Bat guano makes rich fertilizer and provides important nutrients for cave ecosystems. Without the bats, the invertebrates and microorganisms that dwell in caves and depend on bat guano—and the amphibians that de-pend on them—couldn’t thrive.

As in states already affected by WNS, decontamination is a major focus of California’s efforts to prevent its spread. The state now requires researchers who work beneath the earth’s surface—and encourages recreational cavers—to decontaminate all cloth-ing and gear before entering any cave or mine to reduce the risk of introducing the fungus to bat hibernation sites.

Many of California’s abandoned gold mines offer an ideal

setting that could promote the spread of WNS, according to USFS wildlife biologist Linda Angerer.

“I’ve been in very cold, wet mines that mimic caves wonder-fully, and that can provide an excellent environment for WNS,” Angerer said. And bats, she pointed out, are not fussy about their living arrangements. “They roost in everything available; I’ve even seen them in burlap sacks hanging from a rafter in a garage.”

Scientists thought they had a few more years to develop a way to prevent or cure WNS before it reached the West Coast. Because of the devastation of bat populations in the east, a great deal of research is underway to understand the mechanisms by which the fungus causes death and how it is spread between bats and colonies, and to develop methods to control the disease. But effective treatments or vaccines are still years away and now officials in western states are scrambling to establish response protocols and methods for the public to report bats displaying symptoms.

Bronwyn Hogan is the WNS coordinator for the USFWS Pacific Southwest Region (California, Nevada and part of south-central Oregon). She recognizes spread of the fungus as an unprec-edented wildlife health crisis and has sought resources for the agencies that have aligned to fight the problem.

“We are glad that we’ve been able to get funding to western states to help them bolster monitoring programs to establish a better baseline on bat activity and populations ahead of WNS ap-pearing in our region,” Hogan said.

Charged with protection of the state’s wildlife and natu-ral habitat, CDFW has been working with the many agencies involved with the syndrome and its movements. Osborn serves as CDFW’s statewide coordinator for small mammal conserva-tion and coordinates efforts with both the USFS and USFWS. He co-chairs the California WNS steering committee with USFS’ Angerer, working to minimize the risk of the fungus being in-troduced in California, as well as preparing for what now seems inevitable: WNS could begin impacting our bat populations in the very near future.

Since the March discovery in Washington, the committee has asked the organized caving community to help locate impor-tant roosting sites. It has encouraged voluntary decontamination procedures for all cavers at all caves—not just researchers—and urges them to quickly report any evidence of WNS. Committee members have recorded pre-WNS bat calls in order to monitor any precipitous drops in activity levels. Such a sudden decrease in bat activity could indicate an unexplained drop in population, possibly due to a disease such as WNS.

This year, CDFW created a web page with an online reporting form atwww.wildlife.ca.gov/Conservation/Laboratories/Wildlife-In-vestigations/Monitoring/WNS/Report and has asked the public to use it if they find a sick or dead bat with signs indicating possible infection with WNS. (See Signs of White-nose Syndrome sidebar, at left.)

Even though WNS has not been detected in California or Oregon, its presence at North Bend, just 30 miles east of Seattle, is too close for comfort for CDFW’s senior wildlife veterinarian Deana Clifford. Clifford added another layer of defense by reach-ing out to wildlife rehabilitators and the California Department of Public Health. “By working with wildlife rehabilitators and our

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public health professionals, who also receive bats, we are hoping to detect WNS quickly if it comes to California,” Clifford said.

The Threat to California’s BatsTwo bat species that thrive in California—the little brown

bat and the big brown bat—have contracted WNS in other states. Osborn said the disease has hit Myotis species very hard. California bats in that genus include little brown, California, small-footed, long-eared, fringed, cave, long-legged, Arizona and Yuma bats.

“Most of these species have not yet, to our knowledge, been exposed to the disease, so we really don’t know how bad the im-pact will be here in California,” Osborn said.

WNS has also hit the eastern counterpart to California’s canyon bat (also known as the western pipistrelle). Several other bat species have been found with the fungal spores and hyphae

• If you are a recreational caver, do not bring equipment or clothing into California from areas known or suspected to be affected by white-nose syndrome. This now includes the eastern U.S. and Canada, the midwest, the south and the Pacific Northwest.

• If visiting more than one cave or mine in California, decontaminate all clothing and gear between caves.

• Full decontamination procedures for cave enthusiasts may be found here: www.whitenose-syndrome.org/sites/default/files/resource/nation-al_wns_decon_protocol_04.12.2016.pdf

Recreational Cavers Need to Exercise Caution, Stay Clean

A team of Boston University researchers works in Texas on several research projects looking at collective behavior of Mexican free-tailed bats, and how researchers can use computers to track bats in three-dimensional space. While California does not have the large caves that serve as home for bat colonies, like the one above, the state does have many smaller caves and abandoned mine shafts that have a similar environment.

Photo courtesy J. Chenger/batmanagement.com

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(thread-like parts of a fungus) on them, but with no apparent WNS symptoms. These species include the eastern subspecies of Corynorhinus townsendii—Townsend’s big-eared bat—and the silver-haired bat (Lasionycteris noctivagans).

Even within the group of affected bats, there appear to be varying degrees of mortality from the disease. Some species expe-rience devastating losses within a colony, while others suffer less significant mortality rates.

Fourteen of California’s 25 bat species are considered rare or are listed as species of special concern by the state or listed as sensitive by the U.S. Forest Service. One species, a non-hibernating nectar and fruit-eating bat (the lesser long-nosed bat) occurs in California’s southern deserts and is listed as endangered by the USFWS.

“Bats have an energetically expensive lifestyle,” Osborn said. “They’re fliers and they have a large body surface area-to-volume

ratio, which means they need a lot of energy to get around and to maintain their body temperature. That’s why they need to eat all those insects.”

In the winter, when temperatures and insect abundance are low, about half of California’s bat species use hibernation (or torpor) as a strategy to save energy. In parts of the state where winters are cold, the hibernation season may last for several months. In more mild climates, like along the coast and other low-elevation areas, bats may use torpor for shorter periods—ei-ther hours or days—to save energy. It is likely that the greatest impacts of WNS will be to the 17 species that use long-term hi-bernation: Mexican free-tailed bat, pallid bat, big brown bat, little brown bat, spotted bat, silver-haired bat, western red bat, hoary bat, California myotis, small-footed myotis, long-eared myotis, fringed myotis, cave myotis, long-legged myotis, Yuma myotis, canyon bat and Townsend’s big-eared bat.

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One glimmer of hope is offered by the tendency of western bat species to hibernate in smaller groups than their eastern counterparts, which sometimes are found in colonies numbering in the thousands. Western species generally form more isolated clusters with fewer individuals, which Osborn said may result in slower transmission rates and lower rates of infection across the landscape. But he is cautious in his optimism, which he admits may be mostly wishful thinking.

Not all bat species are susceptible to Pseudogymnoascus destructans. Since the fungus thrives in temperatures typical of hi-bernating bats’ bodies, it may not affect species that rely more on migration than hibernation to deal with winter’s harsh energetic conditions. These species include the hoary bat and western red bat. So, at least some of California’s bats are likely to weather the disease unscathed.

In March 2014, bats with WNS were confirmed in 23 states.

Dana Michaels is a Marketing Specialist with the California Department of Fish and Wildlife. Her features in Outdoor California have been recognized repeat-edly by the California State Information Officers Council and this year she won the Gold Award for best feature writing.

From then until now, it has spread to six more states. Wildlife agencies in the western states and provinces had done everything possible to prevent the disease from spreading further. But all of those precautions may not have been enough.

“I had hoped that effective disease controls would be devel-oped before WNS arrived in the west,” said Osborn. “Now it looks like we’ve lost that race and it’s time to prepare for the worst. We’ve got a big problem here, and no solution—yet.”

For more information, visit www.wildlife.ca.gov/WNS.