Bats across North America are being devastated by disease—but here on Nantucket, they’re soaring.
The sun begins to set as Nantucket Conservation Foundation ecologist Danielle O’Dell — also known as the “Bat Lady”— prepares for a night of field work. As she drives down a winding dusty road, the sun’s vermillion rays coat the tips of the pitch pine forest where she and her assistant Libby Buck will set up mist nets across forest trails in hopes of catching northern long-eared bats. “It’s been a lot of work,” O’Dell says. “It’s adapting myself to working at night when I’m inherently a morning person, but I’m learning so much new stuff…It’s inspiring work.”
After dark, the mayhem soon begins as bat after bat flies into the nets where they are then carefully untangled and processed. Taking measurements and skin samples and banding the bats are all part of the field work O’Dell and Buck have trained to do, but they must also check for signs of a devastating fungus killing bats across the country. By swabbing the wings, checking for orange spots under black lights and looking for scars, O’Dell and Buck look for signs of white-nose syndrome.
During 2006 and 2007 in New York, biologists first began noticing bats dying from a mysterious fungus called Pseudogymnoascus destructans (Pd for short). This fungus is the cause of white-nose syndrome, which has quickly spread throughout eastern and central North America from bats hibernating closely together in caves and mines. On infected bats, the fungus coats the wings and face, taking on a powdery white appearance while causing the metabolic rates of the bats to increase, which wakes them from their hibernation. With their wings damaged by the fungus, combined with the difficulty of finding food in the winter, many infected bats eventually starve to death.
Interestingly, bats were not thought to even reside on Nantucket until they were discovered in 2015. While researching the potential impacts of offshore wind on migratory bat species, Zara Dowling, a Ph.D. student at the University of Massachusetts Amherst, put acoustic detectors across the island to see if bats were present. To everyone’s surprise, Dowling’s detectors found that there were plenty of bats on the island. “To have a mammal species escape notice for all this time, after all this study, I just find to be really interesting and inspiring,” says O’Dell. “You think you have a handle on things and then you come to find something totally new…I was super excited.”
In July 2016, researchers placed nets near the acoustic detectors and were able to capture juvenile and lactating female northern long-eared bats, which proved they were breeding on the island. Not only were the bats breeding, but it was soon discovered that they were also hibernating in crawl spaces and basements across Nantucket. According to O’Dell, “that one little piece of information has completely changed a lot of the work that we do at the Foundation,” since much of their work is now centered around summer and winter habitat use of the bats on Nantucket as well as how to manage these habitats to encourage persistence of the species.
The recent detection of northern long-eared bats on Nantucket makes it all the more important to study the species since they are being devastated on the mainland by white-nose syndrome. “Northerns are not doing well anywhere else right now,” O’Dell explains. “In most places you have a very hard time finding northern long-eared bats; they are just gone…So it’s super, super critical that we protect our populations.”
Once found throughout much of the central and eastern regions of the United States and Canada, this species is becoming increasingly hard to come by and is considered a high risk for extinction throughout its range. To date, only one bat has been found to have died from white-nose syndrome on the island, while another tested positive for the fungus that causes the disease, but the overall resilience of the population provides hope for the species.
It’s not exactly clear why the bats are doing so well on the island, but the Nantucket Conservation Foundation has come up with a few hypotheses. First of all, the weather on Nantucket stays warmer for longer into the fall, so the bats have more time to build fat reserves before entering hibernation. This means that in the case of a bat contracting the fungus, they would have enough fat reserves to last them through the relatively short hibernation time. Furthermore, the northern long-eared bats on Nantucket also don’t hibernate with other species in tightly packed caves and mines. In fact, the hibernaculum with the most bats found on the island numbered no more than five individuals, and this significantly reduces the chance of the fungus spreading to a larger portion of the population during hibernation. Whatever the reason for the success of the bats, it is essential that the population is continuously monitored as white-nose syndrome continues to spread.
To many, bats are dirty vermin that are responsible for spreading disease, but these small animals are actually essential parts of most ecosystems. Bats are responsible for consuming large amounts of insects that would otherwise interfere with human health and agriculture, helping farmers save billions of dollars each year. No matter how snaggletoothed or beady-eyed they are, it’s hard to deny the importance of bats despite their vilification in the media. While the population of bats on the island seems steady for now, there are several ways for people to help these creatures continue to thrive. Attracting native insects by growing native plants or maintaining a pollinator garden helps ensure bats have enough food, especially as they prepare for hibernation. Putting up artificial roosts, maintaining forested landscapes and leaving dead trees alone can also provide places for bats to rest during the day. Most important, the Nantucket Conservation Foundation will be working on developing an artificial hibernaculum that could be used by bats as they hibernate throughout the winter. If successful, these hibernacula can be placed on properties around the island and possibly even off-island to reduce the density of bats hibernating in caves and mines, thereby reducing the spread of white-nose syndrome.
As the population of northern long-eared bats continues to decline, Nantucket’s healthy population does offer hope. And biologists like O’Dell will be working hard to study and monitor the species to help maintain its population in the island’s forested areas for years to come.