White-nose syndrome and the Virginia big-eared bat
This peculiar but interesting bat species has been on the upswing since its listing on the endangered species list. Can its success continue in light of a vicious fungus plaguing America's northwestern bat populations?
Monday, April 12, 2010 - 12:38
HANGIN' OUT: Cluster of hibernating healthy Virginia big-eared bats in Pendleton County, W. Va. (Photo: Craig Stihler, WVDNR/Flickr)
What is the Virginia big-eared bat? Corynorhinus townsendii virginiaus is a species of bat native to the Atlantic coast, a "medium-size" type, ranging from 3 inches to 4.5 inches in size and weighing about 0.35 ounces, on average. Their ears alone measure about one inch. Isolated populations reside in Virginia, North Carolina, Kentucky and West Virginia, often in deserted mine shafts and abandoned caves; the caves in which they spend the winter hibernating are called hibernacula. This federal and state listed endangered species does not migrate, which means it is very habitat sensitive. It is also the official Virginia state bat.
On March 15, The Washington Post published a disturbing article about a captive big-eared bat population here in Front Royal, Va. The National Zoo accepted a small population through the Smithsonian Conservation Biology Institute, for protection purposes in November 2009. The project goal was to nurture a small but stable bat population, away from some of the problems facing other eastern bat populations. As the article reported, that project failed. Devastating mortality figures were reported in the Post article; 30 bats of the 40-member population had died, with the remaining 10 still in peril. Questions of management slip-ups, mishandling and bat responses to captivity were raised.
The only response to the Post article is a cryptic statement on the National Zoo website, stating their intent for the project and dismay at the results. "Everyone at the Zoo worked hard to keep these 40 bats alive and healthy. Each death was a blow to the Zoo community and we have taken each death seriously." However, there were no more details given about how or why the remaining ten bats died. There was some allusion that fungus was the culprit, though it wasn't stated clearly or outright. Mishandling and negative responses to captivity were vigorously denied as possible reasons for the mortality rate. " ... [N]ot one of the bats died of capture myopathy (muscle damage caused by the trauma of being captured or handled), of broken legs or arms, or of starvation." Those involved in the project did not respond to this correspondent's inquiries regarding the matter.
What started this whole mess was an altruistic mission to shield the Virginia big-eared bat from a plague of sorts: white-nose syndrome. Bats on the Atlantic Coast are suffering from this syndrome which is a fungus that wreaks havoc on bat systems. Apparently, the fungus causes the bats to behave erratically — in ways that contribute to their demise: often they fly during the day and/or fly during cold weather, hunt during periods when their prey source is unavailable, expending valuable energy on fruitless missions, and reducing fat stores essential to winter hibernation. The mortality rates for infected bats appear to be rather significant. According to the U.S. Fish and Wildlife Service, more than a million bats have died from this mysterious fungal intrusion since January 2007. This map shows hotspots of white nose syndrome infections in this region.
Why should D.C. metro area/Virginia residents care about bats? Well, if you are a follower of this blog, then you already know that this is a muddled question with no single answer. Is this a form of natural selection at work? Is this fungus due to human activities? Should we attempt to help out of a moral obligation, simple scientific interest or from a responsibility as stewards of Earth? As no straightforward answer exists, perhaps the best that can be done is what's already in place: limit human traffic in bat caves to prevent cross contamination, monitor populations and put bat deaths to positive scientific use to determine what remedies may exist to perhaps treat, or at least combat the spread of white-nose syndrome.
Philosophy aside, the Smithsonian project to protect the 40 big-eared bats was its response to this epidemic. There is no reason to try and parse out blame here for the project's failure. Bats are notoriously finicky creatures when it comes to captive care and blame doesn't solve the matter at hand, which is determining what killed those bats and how to help the healthy bat populations stay that way. The attempt to protect bat populations is not endemic to this joint venture either, as several states have petitioned the U.S. Fish & Wildlife Service for grant funds for research/protection measures for their native bat populations.
Since their listing on the endangered species list in 1979, when they numbered just a couple thousand, the Virginia big-eared bat population numbers have steadily increased to somewhere in the range of about 15,000-16,000 (conservatively) in 2000. How they will fare in the face of the white-nose syndrome remains to be seen, but as this fungus tends to be vigorous with its victims, the fact that five Virginia counties already have confirmed white-nose syndrome infections is deeply troubling. No facts or figures regarding bat population counts after this 2009-2010 winter are yet available.
Information on the Virginia big-eared bat and white-nose syndrome is available online at the U.S. Fish and Wildlife website, and at the Virginia Department of Game and Inland Fisheries.