Bats and White-Nose Syndrome

 

The article that mentioned bats and white-nose syndrome in the November 5, 2022, issue presented considerable information about a very serious problem facing bats in North America. At some sites 90%, or more, of wintering bats in a cave die before spring. There is no cure. A number of bat species face a very uncertain future.

Hibernating bats occasionally wake during hibernation to void waste, drink, and sometimes move to a different location within the cave. White-nose syndrome causes them to wake more often. Each awakening uses up fat reserves; therefore, those with the white-nose syndrome fungus may exhaust their fat reserves too quickly. Some may even leave the cave in search of food that is not yet present; this uses up even more of the fat reserves. As with many other animals, when fat reserves are gone death is likely. Some that survive until spring may be in such poor condition that they cannot recover.

As with many (perhaps most) environmental problems, there are groups and organizations conducting research on how to prevent, or at least reduce the severity of, the adverse impacts. Bat Conservation International is active in many aspects of saving bat species around the world. Currently one of their projects is investigating a potential treatment for whitenose syndrome in bats which is sometimes referred to as the “fat bat program.”

A researcher in Pennsylvania noticed that some of the bats surviving the disease were much fatter than he had noticed prior to the disease getting there. Researchers then wondered if one solution would be to get the bats fat enough to survive even if they were infected with the fungus. To test that idea, Bat Conservation International set up experiments at caves and mines in 7 states. The closest one I know of is the Delaware Mine near the tip of Michigan’s Keweenaw Peninsula.

Prior to white-nose syndrome’s arrival there in 2014 surveys found thousands of bats wintering in the abandoned mine. Now there are far fewer bats, and they are scattered along the ceiling. As the bat populations declined, the local people noticed the difference in mosquito abundance which increased greatly. Kyle Seppanen, wildlife coordinator for the Keweenaw Bay Indian Community, has monitored bats there for 6 years and also has noticed the large increase in mosquito abundance. A wildlife technician with the tribe said that last year he used a mosquito net on his head for the first time ever.

The experiment involves a small ultraviolet light bulb that is programmed to turn on every night to attract bugs. Bugs can see ultraviolet light, but people cannot. Not surprisingly this set-up is often referred to as a “bug buffet.” During a previous winter, biologists inserted microchips into the backs of about 300 bats. There is a hoop-shaped scanner near the bulb and when chipped bats fly through the hoop, it identifies each individual bat. This allows them to keep track of how intensively each chipped bat makes use of the bug buffet.

They have only been doing this for 3 years so it is too soon to tell if this can help bats put on enough fat to help reduce the impacts of white-nose syndrome. However, bats do come to, and are using, the bug buffet.

Another interesting aspect is that Mr. Seppanen has been recording bat echolocation calls on the reservation with the aid of a microphone on the end of a long pole. These calls can then be displayed visually to identify which bat species made each call. This information does not give a population estimate, but it can indicate increases or decreases in bat activity. Also of importance is that it allows him to determine locations of greatest use by bats. If a cure for white-nose syndrome is found, he will know the best locations to find and treat bats.

As a side note regarding bats, most of us have probably noticed the abundance of insects (especially moths) which come to outdoor/porch lights. If one wants to have bats come feed on insects in your yard, but do not want to have visible light contaminating your nighttime sky, a good option would be to use an outdoor ultraviolet light as was used in the above study.

Another way to help bats near you is with bat boxes for their summer day-roosting. Google “Bat Boxes” on your computer for information on buying, building, and where to place them as some designs are better than others.

I hope to be submitting columns again, but probably not as frequently as last winter. It is too soon to know how much time will be available. Spring, summer and fall are too busy for me to write. The columns published last May – July were written during winter. I have covered most of the topics I felt were most significant to this area so many future topics may be more general in nature, but still of importance.