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Volume 27
Number 1
Spring 2010
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Bat infected with white-nose syndrome fungus. State of Science
White-nose syndrome in bats
A primer for resource managers
By Kevin T. Castle and Paul M. Cryan
Published: 4 Sep 2015 (online)  •  14 Sep 2015 (in print)
Spread of the disease
NPS-protected resources at stake?
NPS roles
What should national park staffs do?
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White-nose syndrome (WNS) is a disease responsible for unprecedented mortality in hibernating bats in the eastern United States and Canada. This previously unknown disease has spread very rapidly since its discovery in January 2007, and may pose a considerable threat to hibernating bats throughout North America. As white-nose syndrome spreads, the challenges for understanding and managing the disease are increasing.

White-nose syndrome was first observed in four caves near Albany, New York, in the winter of 2006–2007. Before the onset of the disease, decades of winter surveys for hibernating bats that occur in New York indicated healthy and increasing populations (Hicks and Novak 2002). Since 2007, white-nose syndrome has spread more than 1,600 kilometers (1,000 mi) through 11 additional states and devastated populations of bats in its path. As of mid-April 2010, white-nose syndrome has been confirmed as far west as St. Louis, Missouri. Overall declines of hibernating colonies at the most closely monitored New York sites reached 75% within two to three years of initial detection (Blehert et al. 2009). As of winter 2009–2010, white-nose syndrome had been detected in six of the seven species of hibernating bats that occur in the affected region (fig. 1). Species affected to date are listed in table 1.

Table 1. Hibernating cave bats susceptible to
white-nose syndrome

Common Name

Scientific Name

Little brown bat

Myotis lucifugus

Northern long-eared bat

Myotis septentrionalis

Indiana bat

Myotis sodalis

Eastern small-footed bat

Myotis leibii

Tricolored bat

Perimyotis subflavus

Big brown bat

Eptesicus fuscus

The disease appears primarily to affect insectivorous bats while they are hibernating, and hibernators comprise the majority of the 45 species of bats that occur in the United States. Most bats living in cold temperate zones survive the harsh conditions of winter by moving to cold places, where they lower their body temperature to save energy and metabolize stored body fat until insect food becomes available again (Ransome 1990). These flying insect predators are long-lived (approximately 5–15 years or more) and reproduce slowly. Like other top mammalian predators, such as polar bears and mountain lions, numbers of hibernating bats do not fluctuate widely over time, and populations affected by white-nose syndrome will likely take a very long time to recover.

White-nose syndrome was initially named “fuzzy muzzle” by some biologists, for the visible presence of a white fungal growth around the muzzles, ears, and wing membranes of affected bats (fig. 2). In summer 2009, scientists identified a previously unknown species of cold-loving fungus (Geomyces destructans) as a consistent pathogen causing skin infection in bats at affected sites (Gargas et al. 2009). This fungus thrives in low temperatures (5–14ºC; 40–55ºF) and high levels of humidity (>90%), conditions that are characteristic of both the bodies of hibernating bats and the caves and mines in which they hibernate (fig. 3). Chronic disturbance of hibernating bats can cause high rates of winter mortality through loss of fat and possibly water, and effects associated with skin infection by G. destructans may also cause bats to consume critical fat and water reserves too quickly during winter. Aberrant behaviors observed at sites affected by white-nose syndrome can include (1) large numbers of bats moving within hibernacula to roosts near entrances or to unusually cold areas; (2) large numbers of bats flying during the day outside of hibernacula in midwinter; (3) general unresponsiveness to human disturbance; and (4) large numbers of fatalities, either inside hibernacula or near their entrances. Not all of these behaviors may occur at affected hibernacula; this is particularly true of mortality early in the disease onset. Skin infection by G. destructans is a plausible primary cause of mortality associated with the disease. However, the exact processes by which skin infection leads to death remain undetermined and it is unclear whether other underlying conditions contribute to mortality (Meteyer et al. 2009).

One of the greatest mysteries surrounding white-nose syndrome was its rapid appearance. Biologists in North America had never reported white fungus on the muzzles of living bats in winter, yet reports from European scientists indicated that similar fungal growth had been seen on hibernating European bats since the mid-1980s. However, there are no reports of bat mortality associated with such fungal infections in Europe. A recent publication compared small portions of the genome of G. destructans from North America with fungal samples recovered from a French bat (Myotis myotis), and found that the two were identical (Puechmaille et al. 2010). Additional genetic research is being conducted in Europe and the United States to further compare these fungal isolates, to determine if and when G. destructans may have spread from Europe to North America, and to determine why European bats seem less prone to mortality. Bats do not naturally migrate between Europe and North America, so if G. destructans was recently introduced to the United States, it is highly unlikely that it arrived here on the wings of a bat without human assistance.

Bats do not naturally migrate between Europe and North America, so if G. destructans was recently introduced to the United States, it is highly unlikely that it arrived here on the wings of a bat without human assistance.

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This page updated:  13 May 2010

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