October 31, 2013
By: Joshua Eldridge
This just in….An All-Points Bulletin for a missing species has just been released.
The northern long-eared bat (Myotis septentrionalis) has been disappearing from its native habitat throughout North America at an alarming rate since 2006. An estimated 5.5 million cave-hibernating bats have been killed and some populations in the Northeast have been reduced by 99% (USFWS 2013). Because of the startling number and rate of population decline, on October 2, 2013, the US Fish and Wildlife Service (USFWS) proposed that the northern long-eared bat be included for protection under the Endangered Species Act.
The Missing Species
Distinguished by its long ears, the northern long-eared bat is a medium-sized bat that can be found in 39 states including much of the eastern and north central United States and all Canadian provinces. Like many other bats, the northern long-eared bat is most active during the spring, summer, and fall and hibernates during the winter in caves and mines. It feeds on a diverse array of insects and has a relatively long lifespan (5-15 years). However, northern long-eared bats only produce one offspring per year.
The suspected culprit is a fungus called Geomyces destructans (a.k.a. white-nose syndrome). Named after the physical display of a white fungus around the muzzle, ears, and wing membranes of affected bats, it was first observed outside of Albany, New York in the winter of 2006/2007 (USFWS 2011a). On-going research indicates that the fungus was introduced to North America from Europe, potentially transported on equipment from a contaminated site (Sleeman 2011). This cold-loving fungus thrives in low temperatures (40-55° F) and high levels of humidity (>90%) (USFWS 2011a). Previously unknown in North America, the fungus is considered a consistent pathogen as the spores of the fungus remain viable for long periods of time on the surfaces of caves and mines. While it appears to affect different bats species differently, white-nose syndrome always attacks bats during hibernation in the winter and in most cases mortality in the infected population reaches 95% within 2 to 3 years of initial detection. Since the winter of 2007/2008, the fungus has spread to 22 states and five Canadian provinces, killing over 5 million bats.
Humans have played a key role in the spread of this disease. Caves and mines provide the ideal environment for the fungus, which can be spread by humans who enter the sites and come into contact with the fungal spores (Sleeman 2011). While human-assisted transmission does not appear to be frequent, there have been suspicious jumps longer than distances that bats would travel and the jump sites are frequently visited by cavers (USFWS 2011b).
Why It Matters
Bats add a significant value to the agricultural industry – approximately $23 billion (Boyles et al 2011). White-nose syndrome poses a significant threat as nearly half of the 47 species of bats found in North America could be susceptible. Bats consume large amounts of insects and certain bat species can capture from 500 to 1,000 mosquitoes in one hour resulting in an average of 1.3 million insects a year (Boyles et al 2011). In addition to pest control, bats pollinate more than 360 different plant species in the United States and are highly effective at dispersing seeds (Fleming 2011). These benefits to society are often not observed by humans because bats provide their service under the cover of darkness. However, we may soon feel the effect in increased food costs and potentially higher exposures to pesticides as farmers will have to increase pesticide use to counterbalance the decrease in bats as natural insect controls. Furthermore, the projected recovery of bat populations is slow because of the low reproduction rate.
What Can Be Done
As the main accomplice, we need to be aware of and respect cave and mine closures. Although many people enjoy exploring caves, a number of them have been closed to prevent exposure and spread of this deadly disease. If you enter, or are around caves or mines, clothing must be properly decontaminated before and after you leave the cave. Washing your caving clothes will help keep the disease from spreading to uncontaminated sites (Sleeman 2011). Finally, if you notice bats flying in daylight during the winter months or clustered near the entrances of caves, alert your local USFWS office.
The spread and impact of this disease is unprecedented for bats in North America. Action plans to protect bats and help the recovery of the affected populations are underway, but we can help keep these creatures of the night from vanishing.
Boyles, J.G., P.M. Cryan, G.F. McCracken, and T.H. Kunz. 2011. Economic importance of bats in agriculture. Science. Vol 332. No. 6025. Pp. 41-42
Fleming, J. 2011. Why we should care about bats: Devastating impact white-nose syndrome is having on one of nature’s best controllers. U.S. House of Representatives Subcommittee on Fisheries,
Wildlife, Oceans and Insular Affairs Committee on Natural Resources. Washington, D.C. June 24, 2011.
Sleeman, J. 2011. Universal precautions for the management of bat white-nose syndrome (WNS). USGS National Wildlife Health Center. Madison, WI.
USFWS. 2011a. A National Plan for Assisting States, Federal Agencies, and Tribes in Managing White-Nose Syndrome in Bats. USDI. Washington, D.C.
USFWS. 2011b. Human Spread of White-Nose Syndrome: Why Decontamination is Important. USDI. Washington, D.C. New York Field Office.