What's Threatening our Bats?

  • White Nose Syndrome
  • Protecting western Canada from WNS
  • Disturbance During Hibernation
  • Habitat Loss
  • Wind Farms
  • White Nose Syndrome (WNS)

    In 2006, an unusual fungus was first noticed by cavers in New York State, growing on hibernating bats in Howes Cave.  Since then, this disease, which is typified by white fungus growing on the nose and other exposed flesh of bats, has spread across much of North America, wiping out up to 99% of bats from hibernacula.  The bats will arouse frequently to groom the fungus from their skin and to allow their immune system to return to a normal state for fighting infection; this burns up their precious fat reserves. Eventually, the hungry bats will venture out into the winter to seek food, only to die from starvation. The disease also has systemic effects which cause acidosis of the blood, which may cause physiological failures resulting in mortality. The disease is caused by the Pseudogymoascus destructans (Pd) fungus and was somehow imported from Europe, where it is endemic, as it is in Asia.  Species of bats are at risk of extinction or extirpation, with three species currently classified as endangered in Canada due to the outbreak (Little Brown Myotis, Northern Myotis, Tri-coloured Bat) and others becoming at risk as the infection spreads. In the US, two endangered and one threatened bat species have been infected, with a total of 13 species affected by the disease across the continent.  In some cases, almost 100% mortality is being reported at cave hibernacula - where there used to be thousands of hibernating bats, there are now only carcasses.  Due to their slow reproductive ability, bats cannot rebound from mass die-back and thus ecosystems in areas of WNS infection are likely to be impacted over the long term by the loss of natural insect control.

    Currently, research into strategies for mitigating the effects of WNS are ongoing.  The longer the west can remain free of the Pd fungus, the more time there is to develop these critical conservation strategies.

    Protecting western Canada from WNS

    What we know to date is that this disease is passed primarily by bat to bat contact, but it is highly likely that spores could be passed by other means as well.  For this reason, protocols are being established for western Canada to slow the spread of WNS into the west.  The greatest risk from humans is if a person visits caves or mines where WNS exists in the east and then travels west, introducing the spores to caves or mines there.  This disease does not affect humans, but sudden introduction of WNS to bats in the west would be catastrophic.  Clothing, helmets, footwear and other caving equipment should be thoroughly decontaminated using the procedures found here. This protocol, specific to western Canada, was established in consultation between government, bat biologists and cavers. As decontamination procedures are refined and thoroughly tested, it may be that in the future all caving gear used in WNS infected areas can be safely decontaminated and used again in the West.  Until then, it is recommended that if you go underground in a cave that houses WNS infected bats, that you do not use that gear underground in western Canada. 


    Disturbance during Hibernation

    During hibernation, bats go into a dormant low energy state.   Their bodies cool almost to the cave temperature which ideally remains just above freezing and they also prefer a high humidity environment which slows dehydration.  Their heart beat slows to 3-5 beats per minute and their respiration also drops.  In this way they conserve energy and use their stored fat to survive the long winters when there are few bugs to eat.  At this time, disturbance of bats can cause them to arouse, which burns more energy.   It is imperative that if you see hibernating bats that you leave them undisturbed.  They can be woken by sound, light, even your body heat.  They can take up to 20 minutes to wake up so you might not even realize you have disturbed them.  Repeated disturbance can burn so much of their body fat that they may not survive the winter.  As a rule, cave passages where bats are known to hibernate should not be visited during winter.

    Another threat to bats during hibernation are blasting activities.  Road or other blasting work conducted within a mile of bat hibernacula can be extremely disruptive as shock waves are powerful enough to dislodge hibernating bats.  Work in proximity to bat caves should be conducted when bats have left hibernacula; generally, June through September.


    Habitat Loss

    Habitat loss is causing declines in bat and other wildlife populations worldwide.  Bats use older trees for roosting in various ways.  They will hang under large moss-line branches, secrete themselves within furrowed and exfoliating bark and use hollows within trees.  These can be night or day roosts and can also be maternity colonies if they are secure and warm enough.  Older trees can provide an uncluttered understory which encourages feeding by bats.  Conversely, young post-logging forests lack most of these attributes.  Other forms of habitat loss include destruction of cliff roosts by quarrying, repeated human disturbance of cliff roosts by climbers and cave habitat by cavers, and pollution.  Disturbance by ongoing blasting such as at mines can create exclusion zones from bat habitat.  On the plus side, bats will use houses, other structures, and disused mines for roosting or hibernation.  Some bats are more adaptable than others to habitat disturbance but rare species can be pushed toward extinction due to more specific requirements.

    Wind Farms

    Wind farms are responsible for the deaths of thousands of bats and birds annually due to collisions with turbine blades.  This mostly affects high-flying and migratory bats.  Research into deterrence and mitigation strategies is ongoing.  Site placement can have major effects on mortality.  Deterrence can include using ultrasonic emitters to warn bats when they are too close to the blades, while halting the turbines in 'shoulder' periods (when power generation is minimal due to little wind) can minimize mortality.  In the long term, abandoning moving blades for other forms of wind generation may be a better solution.  One promising strategy is 'reed' generators which use tall strips that bend with the wind, generating piezo-electric power.


    Protect Bats

    Bats are very sensitive to disturbance while hibernating. If you see hibernating bats, leave the area immediately.

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    Clean Gear

    Decontaminating your gear between caving trips can prevent the spread of WNS.

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    Find Bats

    Install a bat monitoring device in a cave or mine when you go caving.

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    The BatCaver program has released a video (see below) demonstrating one easy method of decontaminating caving equipment after exiting a cave or mine. Our BC coordinator walks the viewer step-by-step through one of his common decon procedures: immersing his caving equipment in 60-degree Celsius water for at least 20 minutes. The video is intended to help increase the likelihood that more people will follow recommended procedures by simplifying the procedure that reduces the risks of inadvertently transporting White-nose Syndrome (Pd) spores from one region to another.

    White-nose Syndrome has continued spreading westward through Manitoba. It has also been found in Washington State since 2016.  As this highly transmissible and fatal disease of bats continues its spread, adherence to proper decontamination protocol is increasingly important, especially among anyone who may enter multiple caves or mines in a wide geographic range, and anyone operating in the Fraser Valley and US border regions.


    Additional decontamination procedures can be found under the decontamination protocol link on the BatCaver Resources page. A map of WNS affected areas of North America (2019) is found on the Threats tab.


    White-nose Syndrome (WNS) is a fungal disease that has caused up to 100% bat mortality in cave hibernacula in Eastern Canada and United States. Follow these simple and critical decontamination protocols to keep bats safe as you explore. 



    Watch this video in French.

    © 2020 Wildlife Conservation Society