By Zack Steel
First, I’ll provide a few tidbits to convince you that bats warrant your attention before delving into the crisis of this particular drama. Despite their relative obscurity and perceived malevolence in our culture, we know bats are important critters, both ecologically and economically. Bats are the second most numerous order of mammals after rodents and are the only mammals capable of true flight (sorry “flying” squirrels). Most species are insectivorous, including within the United States where they provide more than $3.7 billion worth of pest control for agriculture annually. Around the world they also act as important pollinators and seed dispersers – and yes a few drink blood. The smallest species is the Kitti’s Hog-Nosed Bat, whose bodies are less than two inches long, and the largest are a group collectively called “flying foxes”, which can have wing spans up to 5.6 ft!
Ok, now that you are enamored with the protagonists of this story we’ll move on to the crisis…
About a decade ago the fungus Pseudogymnoascus destructans appeared in upstate New York, apparently hitching a ride on the clothing of recreational cavers traveling from Europe. This particular fungus is problematic because it causes what is known as White-Nose Syndrome (WNS) in bats. WNS does not kill bats directly, but infects the wings, ears and of course the nose of individuals, where it causes tissue damage and general stress to the animal. During winter months when many bats typically hibernate, infected individuals will awake often, further reducing energy reserves and potentially leading to starvation.
Species confirmed to be susceptible to WNS
- Big brown bat (Eptesicus fuscus)
- Eastern small-footed bat (Myotis leibii)
- Gray bat (Myotis grisescens) - Endangered
- Indiana bat (Myotis sodalis) - Endangered
- Little brown bat (Myotsi lucifugus)
- Northern long-eared bat (Myotis septentrionalis) - Threatened
- Tricolored bat (Perimyotis subflavus)
Judging by the rate of spread through 2015, it was believed that west-coast bats, and those concerned about them, had a few years until WNS made its appearance among us. However, this past March a Little Brown Bat infected with WNS was found near Seattle, WA, far from the nearest known infection site. It’s unlikely that this is the sole infection in the area, but its also unclear how rapidly and widely WNS will become a problem out West. If the consequences to bat populations in the eastern US are any indication, we may soon begin to see dramatic effects on western bat populations, and on the ecological processes that depend on them.
So what is to be done about WNS? Unfortunately, to date there is no silver bullet. The US Fish and Wildlife Service is implementing a nation-wide plan, which is largely defensive, focusing on surveillance and prevention of human-spread of WNS. Without an obvious cure, the hope is that resistance within affected populations will be widespread enough to allow recovery following initial infection and die-offs. In the meantime we need to learn more about these under-studied animals, both where they are currently being affected by WNS, and in places like California where baseline information on population levels and bat ecology is limited. If you are a caver or a bat researcher, there are decontamination procedures available to help prevent inadvertent spread of the disease. For the rest of us, we can provide roosting habitat in old barns, live and dead trees, or build bat houses, and report any signs of sick bats to the USFW.
So I don’t end this story on a depressing note, check out this video on the healthy colony of 250,000 Mexican Free-tailed bats under the I-80 causeway between Davis and Sacramento. Or better yet, go witness their impressive nightly emergence yourself.
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