Last November, the National Zoo accepted 40 endangered Virginia big-eared bats (Corynorhinus townsendii virginianus) to establish a security population and scientifically develop husbandry practices—a feat no one else has undertaken with this subspecies. In the months since, efforts to keep the bats alive have proved challenging, but the lessons Zoo scientists have learned will help save these, and other, insectivorous bats in the future. Last year the U.S. Fish and Wildlife Service funded this and other research projects focused on white-nose syndrome and bat survival. The West Virginia Division of Natural Resources has also assisted with the project.
An estimated million bats have died in the Northeastern United States from white-nose syndrome, a disease characterized by a white cold-loving fungus that invades the skin of the bat (mainly the muzzle, ears and wings). The bats lose their fat reserves and ultimately starve. The bat colony has been living at the Smithsonian Conservation Biology Institute (formerly the Conservation Research Center) in Front Royal, Va. The possible extinction of an endangered subspecies, and the loss of its essential role in local ecosystems, were the reasons the National Zoo accepted the high-risk project.
Over the past four months, the majority of the bats have died; 11 bats remain in the National Zoo’s colony. The initial challenge the team faced was how to feed the animals. Virginia big-eared bats, which are a subspecies of the Townsend’s big-eared bat (Corynorhinus townsendii), eat on the wing (in flight). While some in the security colony successfully learned to eat meal worms out of pans, others did not, sometimes resulting in their death. Some of the bats that ate mealworms did not adequately groom themselves, which resulted in dermatitis (inflammation of the skin). Others developed foot, toe and digit problems that, in part, may have caused deadly bacterial infections that spread rapidly through the blood stream despite aggressive treatments with antibiotics and fluids.
"Virginia big-eared bats face an imminent threat from white-nose syndrome,” said the U.S. Fish and Wildlife Service's National White-Nose Syndrome Coordinator Jeremy Coleman. “Developing a successful captive breeding program is a reasonable precautionary step to ensuring the long-term viability of the subspecies. The Smithsonian’s National Zoo was the only organization to accept the challenge of this risky, groundbreaking, but essential endeavor.”
Because it is extraordinarily difficult to maintain insect-eating bats in captivity, extensive planning and preparations went into designing the project. The Zoo formed a bat care team made up of biologists, husbandry and animal care specialists, veterinarians and a nutritionist who relied on protocols developed by the Virginia Big-Eared Bat Group convened by FWS. The SCBI team worked around the clock to care for, and learn from, the colony.
“We expected some of the feeding challenges,” said David Wildt, head of the National Zoo’s Species Survival Center. “But we were surprised to learn how sensitive this particular subspecies of bat is. Even the smallest change in environment or husbandry practices seemed to affect the ability of the bats to adapt to their new environment.”
National Zoo researchers found that bats learned to eat from the bowl faster when confined in a small enclosure for a few hours. In the future, scientists could use this information to better provide for the needs of the subspecies in captivity. The bat team learned a great deal about enclosures and medical care required for insectivorous bats in captivity.
“Faced with the possibility of white-nose syndrome eliminating the entire subspecies, we took decisive action to attempt to protect the bats,” Coleman said. “Together with the Zoo, we will examine this project, take what we have learned and be ready to apply it to captive propagation projects in the future.”
White-nose syndrome continues to devastate wild bat colonies. The fungus is now present in caves in West Virginia that support the largest hibernating populations of Virginia big-eared bats in the world. It has spread to 10 states, from New Hampshire to Tennessee, and more endangered bat species are now within its range.