By: Trina Morris, Georgia DNR Wildlife Biologist
Just a couple of years ago, a survey at Black Diamond Tunnel was one of the highlights of our seasonal checks of bat caves.
We’d load up a boat and drive to Rabun County early in the morning and usually in bitter cold. As we climbed the steep driveway to the landowner’s house, we would be excited about catching up with Regina and her dogs after another year had passed. During the survey, she would wait patiently for us at the tunnel entrance, making sure we returned safely and hoping for good news about the bats that meant so much to her and her family.
Last year was the year that we had all been dreading. We came out of the tunnel with the news that bats in Black Diamond had white-nose syndrome, the disease that has killed more than 5.7 million bats in North America. The news was devastating but not unexpected. White-nose, or WNS, had been found in Georgia in 2013; it has since spread across north Georgia into every site we regularly check.
Snow delayed this year’s visit to Black Diamond, but made a beautiful sight outside the tunnel from the photos Regina shared. When we finally made the journey, we were all worried about what we might find. Regina greeted us as always, and later softened the blow of what we found by delivering delicious, homemade cookies after our trip into the tunnel. The news we brought was much less sweet. Only two years after white-nose showed up at Black Diamond, bat numbers at the site had dropped by 89 percent.
The tunnel is not an exception. At Sitton’s Cave in Cloudland Canyon State Park, where WNS was first detected in the state, we saw 94 percent fewer bats this winter than in 2013. On Crockford-Pigeon Mountain Wildlife Management Area, bat numbers at Ellison’s Cave were down 85 percent.
I could list the other sites, but we found the same thing across the state. Most of the bats are gone.
Unlike some of the sites in the northeastern U.S., we rarely see large numbers of dead bats inside Georgia caves. We assume most of the bats fly out on the landscape and succumb to the disease out of sight. And we prefer it that way.
At Anderson Springs Cave near Lafayette, we knew things were bad as soon as we entered. We could smell it.
We enter the cave through a passage carved by flowing and shockingly cold water. The entrance is beautiful, and we always begin to see bats before the shock of the icy water has subsided. But this year the majority of the bats near the entrance were dead and in various stages of decay.
Dead bats hung on the walls, encapsulated in the fungus that takes over after WNS kills them. Bats lying on the rocks appeared to have died in mid-flight, tattered wings outstretched toward the exit. Trying not to focus on the scene or the putrid smell, the survey crew quietly counted the live and the dead. The bat numbers had only declined by 34 percent at this cave, but WNS was slow to arrive here, showing up in winter 2014. Next year’s numbers will likely be right in line with the other caves we survey.
Our final survey at the end of March was in a Floyd County cave that had somehow escaped infection before. We were holding onto hope that the site, much drier than most other caves surveyed, might once again provide a refuge for the few hundred bats we usually find there. But as soon as we passed through the uncomfortably tight squeeze into the cave, we saw the signs.
White, fuzzy noses and wings were obvious on bats that dotted the walls and peeked from cracks in the rock. Half of the bats at the cave were missing. Maybe they left early taking advantage of the unusually warm weather. But even if they get through this summer, the fungus awaits their return in the fall, and will likely kill most of them.
When we got back to the office, clean and disinfected after weeks traveling underground, we tallied up the numbers. This year’s bat totals were down 82 percent from previous winter counts.
Most of the missing are tri-colored bats (Perimyotis subflavus), the most common winter cave bat in Georgia. Yet we also saw declines in northern long-eared bats (Myotis septentrionalis), a species just listed as threatened by the U.S. Fish and Wildlife Service but never found in large numbers in our caves. We only saw one little brown bat (Myotis lucifigus), but it’s unlikely that animal will return next year. It was the first little brown confirmed with WNS in the state and the first bat we have seen still living with extensive wing damage from the fungus.
If you follow the stories about white-nose, there are glimmers of hope. Headlines like “Some Bat Colonies Might Be Beating White-nose Syndrome” and “Hints of Hope Emerge in Deadly American Bat Plague” are positive. These articles focus on survivors or bats that hang on year after year in infected sites. There are still many unknowns, and maybe some can make it.
But even if these bats survive and continue to reproduce, recovery will be slow. Bats are long-lived and most have only one pup a year. They are not a group that will bounce back fast.
There are new treatment options being developed. Naturally-occurring volatile organic compounds are being tested for their anti-fungal properties. Bacteria found in the wild on some bats may explain higher survival rates and could be used to treat other infected bats. However, trials take time and large-scale treatment isn’t easy. Many of our bats have already run out of time.
We are not giving up hope. Georgia will have survivors. We also have bats that aren’t affected by the disease, such as species that don’t hibernate in caves, where the cold-loving fungus that causes white-nose can thrive.
But we have to provide our bats with what they need to survive. All of them use forests during some portion of their life for roosting, foraging and drinking. Even urban forests and backyards can be important for bats.
And with the specter of white-nose syndrome shadowing them, they need our help more than ever.
Check out DNR’s Georgia Wild e-newsletter for soon-coming articles about what bats need and how you can help. And watch the skies at dusk to see if you can spot these fast-flying mammals!