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Fort Delaware joins battle to protect bat population

As Fort Delaware State Park kicked off its 2012 season last weekend, park rangers and guides started enlisting visitors to help the park’s seldom-seen bats. Visitors to the fort are being asked to assist in the effort to curb the spread of the disease known as white-nose syndrome (WNS) to other parts of the country.

Around 6 million bats have succumbed to a deadly fungus in just five years in the eastern United States and Canada. Some species, such as the little brown bat, have lost of 90-95 percent of their populations. This winter, the culprit took up residence in Fort Delaware State Park.

Holly Neiderriter of Delaware Div. of Fish and Wildlife discusses Fort Delaware’s role in protecting bats

Holly Neiderriter of Delaware Div. of Fish and Wildlife discusses Fort Delaware’s role in protecting bats


Fort Delaware joins battle to protect bat population

“Honestly science has never seen a mammalian disease catastrophe like this,” says Holly Niederriter, wildlife biologist for Delaware Division of Fish and Wildlife. “I’m not even sure that the Plague reached these proportions [in terms of percentage of the population killed] .”

Niederriter oversees the state park’s bat program. After finding a few sick bats at the fort this winter, her job instantly got more complicated.

Fort Delaware has long been a hibernation destination for bats. Without any mines or caves, the state offers few locations suitable for bats to overwinter.

This winter, Niederriter says that she counted around 100 bats hibernating in Fort Delaware, but added that was likely a small fraction of the number actually resting in the eaves. She cannot accurately say how many of those spotted were infected, since not all bats who have contracted WNS display visible signs.

Fort Delaware joins battle to protect bat population
Little brown bat; close-up of nose with fungus, New York, Oct. 2008. (Courtesy: Ryan von Linden/New York Department of Environmental Conservation).

Unlike topical fungi familiar to humans, such as athlete’s foot, this fungus invades skin cells and penetrates the wing fibers where it disrupts the physiological system, blood flow, and electrolyte levels. The telltale white fuzz only appears after the fungus has become fully established on the animal.

The fuzz on the wings can be enough of an annoyance to rouse the bat from hibernation to groom off the fungus. Once awake, the bat will fly off in search of food and water using up energy stores intended to sustain hibernation. Many do not survive the winter.

Healthy bats typically live around 30 years. Reproductive females give birth to just one pup per year and the rate of survival during normal circumstances is only 50 percent. With millions of bats succumbing to this epidemic, there is real concern that some species could face extinction in years to come, says DeeAnn Reeder, assistant professor of biology at Bucknell University in Pennsylvania.

Reeder’s lab has refocused nearly all research hours on white-nose syndrome since 2008, looking specifically at survivors in hopes of unlocking the secret to their resilience. If that resilience is heritable, natural selection could potentially work to save entire species.

Fort Delaware joins battle to protect bat population
Map of suspected and confirmed locations of WNS in the United States and Canada (click to enlarge) (Map by:Cal Butchkoski, PA Game Commission.)

“For now, we have virtually no tools for stopping this and keeping the bats from spreading the fungus. One of the things that we do have in our power is to keep people from spreading it,” Reeder says.

That becomes a daunting task at a major attraction like Fort Delaware.

Every year, some 20,000-30,000 visitors board the Three Forts Ferry to visit the Civil War fort and state park on Pea Patch Island. Most of them will never see a bat while on the island. The nocturnal mammals tend to come out after dark and the last ferry has returned to the mainland.

While white-nose syndrome does not affect people, visitors can unknowingly carry the fungus responsible for the syndrome to bats in other parts of the state or country.

Biologists believe that the fungus first arrived in the United States after stowing away on a tourist’s camera bag or hiking boots. The fungus is abundant in caves in Europe but European cave bats do not succumb to white-nose syndrome.

The floors and walls of the fort are covered with microscopic fungal spores, or conidia, lying in wait for a sleeve, shoe, or stroller to stick to and hitch a ride somewhere else.

Given the unique nature of Fort Delaware as a manmade structure that the bats have turned into a habitat rather than a natural ecosystem could in theory allow for chemical decontamination of the area. However, the fort is an historic building and there are concerns that the compounds could harm the actual building, says Niederriter.

Park officials have instead focused their efforts on visitor education. Before entering the fort, visitors are reminded to take care not to brush up against any walls inadvertently, especially the brick and concrete. On the way out of the park, visitors will are asked to walk across a mat containing a hospital-grade decontaminate solution. (Closed toed shoes are recommended to protect the skin from the solution.) Visitors are further advised to avoid wearing the same clothes and gear when visiting other natural areas.

Fort Delaware joins battle to protect bat population
Little brown bat with white-nose syndrome in Greeley Mine, Vermont, March 2009.(Courtesy: Marvin Moriarty/USFWS).

“This is a fairly unique situation because a lot of the caves where [WNS] been documented the answer is just close the cave. Or if you do let people go in, the people who go in are all cavers who really care and are really enthusiastic about bats and are fully willing to do all decontamination protocols if they are going to another place,” said Niederriter. ”[Fort Delaware] draws all kinds of people. It’s a tourist attraction.”

This weekend, park interpreter Laura Lee welcomed the season’s first 150 visitors. Once Lee reassured guests that the fungus presents no health threat to humans, she says that people seemed interested in helping out and learning about the presence of bats at the fort.

“I see this as a perfect teaching moment as an opportunity to make people aware that Fort Delaware has more than history. There is a lot of nature here as well, from the heron rookery, to the wetlands, to the bats,” Lee says.

While much of the public may not be very familiar with bats, they play a vital role in agricultural production, eating hundreds of tons of nocturnal insects that would otherwise devour crops intended for human consumption.

“We don’t fully understand yet what the ecological consequences of this epidemic will be,” says Reeder.