Little brown bat with symptoms of WNS. Photo by Dave Riggs.
Many of North America’s bats are in grave danger - but would it help to add them to the U.S. government’s endangered species list?
Bat populations, especially in the Northeast, are being decimated by White-Nose Syndrome, or WNS. First identified in 2006 in New York state, WNS has spread rapidly throughout bat habitats in the eastern part of the continent, from Canada as far south as Mississippi. The disease is named for the characteristic fungus that appears on affected bats’ muzzles and wing membranes. Millions of bats have died among the seven North American species affected.
The U.S. Fish and Wildlife Service recently listed one of these species, the northern long-eared bat, as threatened. While not as severe a listing as endangered, threatened status still grants protections through regulations outlined in the Endangered Species Act, including prohibitions on harming members of the species or destroying their habitats except under certain conditions.
Unfortunately, the problem for bats has nothing to do with the trees in which they roost in the summer or, for that matter, anything that happens after their normal winter hibernation period. The fungus is attacking them in their hibernacula (that is, the caves and mines where they spend the winter). Yet the Fish and Wildlife Service has issued regulations restricting cutting down trees where the bats roost. This will complicate, and potentially curtail, activities ranging from forestry and oil drilling to housing development and landscaping.
Some industries are resisting, on the not-unreasonable basis that expensive, disruptive steps to possibly preserve a few bats in the summer will accomplish nothing if those bats return to caves where they will die in the winter. The public has been invited to comment on the proposed rules until July. Neal Kirby, a spokesman for the Independent Petroleum Association of America, told The Wall Street Journal, “The agency itself has acknowledged that industry is not a culprit of the bat’s demise, it is this fungal disease.”
When a species’ population density in a region drops so low that the surviving individuals cannot find mates with which to reproduce, there comes a point where every individual counts. The service may simply be trying to buy the bats some time. The rate of WNS’ spread, though, suggests this attempt will be far from enough.
In Vermont, the little brown bats that used to visit my home every summer have all but vanished without a trace. While the bat’s range is wide enough that it is not yet in danger of extinction, Vermont and other Eastern states have sounded the alarm that their populations may vanish within as little as 15 years if WNS continues unchecked. The northern long-eared bat, which also lives in Vermont but does not range nearly as far west, may be in more immediate danger of outright extinction.
If we really want to protect at-risk bat species, either we will have to go into key wintering habitats and decontaminate them during the summer months or we will need to pursue some sort of captive breeding program in order to keep enough bats alive to preserve the species gene pool until a longer-term cure for the disease is discovered. This latter option may not even be possible; unlike rodents, for example, bats don’t have large litters and thus regain population only slowly over time. The Interior Department released a national response plan in 2011, and several states also have WNS response plans in place, most of which include some combination of population monitoring, disease research and decontamination efforts.
One argument for recognizing a species as threatened or endangered is to draw attention to the species’ situation. The government must take serious conservation measures to preserve the habitat of the species under pressure, and conservationists can underscore the dire nature of the situation. But the bats’ plight is well-known. Given bats’ mixed popular reputation, the amount of mainstream coverage and sympathy may even be somewhat surprising.
But sympathy alone won’t save bat populations. Increased funding support may help in the pursuit of a cure, but so far, the best we can do is attempt to slow WNS. We have no way to stop it, and designating a species threatened, or endangered, won’t change that fact. If it is feasible to eradicate the fungus in critical habitats and keep it out - a proposition that is far from certain at this point - no one has yet committed enough money and manpower to determine how to do so and put that plan into action.
Until and unless we find a cure, all our other efforts probably can do no more than slightly delay the inevitable. We might as well wait for the bats to deal with the problem through natural selection that, we can hope, might give rise to a more resistant population. There is grounds for that hope in the example of European bats, which coexisted with the WNS fungus for centuries before it was inadvertently brought here, probably by cave explorers. If natural selection does not do the job, bats may eventually repopulate affected areas in the distant future, if the fungus dies out on its own.
Neither of these solutions are guaranteed. But so far, we haven’t found anything substantially more helpful. Adding bats to the threatened or endangered species lists will not accomplish much except to make us feel that we are doing something useful, even if we are not.