I’m Still Batty About Bats
Last week we discussed the marvelous physiological adaptations and ecological roles of Pennsylvania’s bats. And yet, there is still so much more to talk about! Let’s continue our Bat Week celebration as we learn about the various threats facing our furry friends in the sky.
Drawing of a bat from Canva.
Bat populations face several forms of anthropogenic threats, such as hibernation disturbances, introduced disease, highway mortality, and windmill farms. The increasing presence of windmills on ridgetops pose a threat particularly to migrating bats; however, studies have shown that slight restrictions on the operation of these windmills during the migration season can significantly decrease consequent bat mortality. Scientists also suspect that the pervasive use of pesticides is detrimental to bat populations. Although, the single largest threat to our bat populations is white-nose syndrome [1].
White-nose syndrome (WNS) is a disease caused by an exotic fungus, Psudeogymnoascus destructans, which was introduced to the U.S. a decade ago. Identifiable by the white fungus which grows on the bat’s muzzle, this disease forms lesions on the bat’s wings. Bats suffering from WNS will rouse from hibernation prematurely; this disturbance causes them to burn through their stored, winter fat, which subsequently causes them to futilely attempt to forage for unavailable food sources. Unfortunately, these bats often die of starvation or dehydration from the deadly domino effect of this disease [2]. Pennsylvania’s three migratory species have not yet been confirmed to have WNS. However, all six of Pennsylvania’s hibernating bat species have seen a catastrophic population decline of 99% due to this disease. In combination with this lethal disease, hibernation disturbances (like curious, cave-exploring humans) can further exacerbate their fat reserves. Thus, it’s essential to be mindful of the homes of hibernating bats, avoiding these hibernacula (overwintering shelters-- think caves, mines) as much as possible [1].
So, you shouldn’t disturb bats in their homes, but what if bats have made their way into yours? After spending the winter months in their hibernacula, bats will emerge in the spring to reproduce. At this time, female bats will be looking for some new real estate to raise their young. Perhaps your attic has become the summerhouse of a maternity colony. Now what do you do? Of course, extermination should not even be considered. Beyond the inherent value of this important species, extermination is a temporary, ineffective method, as it’s only a matter of time until other bats find their way into your attractive home. However, in the fall, bats will naturally leave your house to return to their hibernacula for winter. If you observe where the bats fly out of your house, you’ll be able to seal off these areas to hamper their return. It’s important to note that bats often live for 20-30 years, and they are notoriously faithful to their chosen neighborhood. This means, while you may have closed your home to these batty visitors, your neighbor’s house could be their new motel. The most permanent solution to this housing crisis is to provide a bat box. By installing a bat box, you, your neighbors, and your neighborhood bats can live harmoniously in your respective homes. Be sure to research the appropriate dimensions and locations to optimize the effectiveness and attractiveness of your bat box [3].
You can find a plethora of resources, including information on bat structures and articles detailing how to handle bats in your home, at https://www.pgc.pa.gov/Wildlife/WildlifeSpecies/Bats/Pages/default.aspx. To read about Pennsylvania’s bats in greater detail, visit the websites cited throughout.
[1] https://www.pgc.pa.gov/Education/WildlifeNotesIndex/Pages/Bats.aspx
[2] https://waterlandlife.org/wildlife-pnhp/species-at-risk-in-pennsylvania/bats/
[3] https://www.pgc.pa.gov/Wildlife/WildlifeSpecies/Bats/Pages/BatProblemsSolutions.aspx
Written by Faith Forry — November 11, 2020
