Search

Virginia Big-Eared Bats at the National Zoo

A Risky—But Worthy—Endeavor

Learning how to care for an endangered species on the fly, so to speak, is one of the biggest challenges that conservation biologists face. But in early November of 2009, in the wake of a fungal disease (white-nose syndrome) that is wiping out bat species in the northeastern United States, National Zoo researchers accepted a grant to work on the critically endangered Virginia big-eared bat (Corynorhinus townsendii virginianus), which is a subspecies of the Townsend’s big-eared bat (Plecotus townsendii).

After the U.S. Fish and Wildlife Service and West Virginia Division of Natural Resources collected 40 non-infected bats, National Zoo scientists established a colony at the Smithsonian Conservation Biology Institute near Front Royal, Virginia. As the National Zoo has been successful with establishing security populations of other endangered species, the goal was to determine if it was possible to keep this specialized bat subspecies alive in captivity. The need was urgent—the syndrome has killed more than one million bats, with mortality as high as 95 to 99 percent in some caves.

It is extraordinarily difficult to maintain insect-eating bats in captivity. The National Zoo team realized the risks, but conservationists know there is always much to be learned when an opportunity presents itself. 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. When the bats arrived in early November, a "bat care team" made up of biologists, husbandry and animal care specialists, veterinarians, and a nutritionist worked nonstopday and night to care for, and learn from, the colony.

What follows is an account of what we’ve learned so far about husbandry practices related to these animals, the challenges we’ve faced, and how we can apply this knowledge to similar efforts to save these bats in the future. Check back for updates.

The Challenges

We’ve encountered challenges in establishing a stable population of the Virginia big-eared bat in captivity:

  • The time of year that scientists collected the bats seems to have influenced their ability to survive in captivity. But because white-nose syndrome was fast approaching the habitat of the Virginia big-eared bat, it became urgent to establish a security population quickly, before winter began. So the bats were collected during the time when some were approaching, or perhaps had already begun, the hibernation process. This meant that some of the animals were lethargic and resisted eating, which no doubt contributed to the inability of some of bats to adapt to captivity and to early mortalities.
  • Not only are these animals insectivores, which means they survive on eating insects, they prefer to feed "on-the-wing," or to catch insects while in flight. For months, the team worked hard to train the bats to eat insects (mealworms, specifically) from food pans. For those that learned to eat the mealworms, the habit stuck as long as there was no change in feeding routine. The team’s attempts to stimulate the bats to eat other insects (crickets or free-flying moths) were not successful.
  • As bats are "metabolism machines," the team soon found that individuals could suddenly show drastic declines in body weight that often required immediate attention. Some bats, while learning to eat juicy mealworms, did not adequately groom themselves, which resulted in dermatitis (or inflammation of the skin). Others developed foot, toe, and digit problems. Some of these bats died due to the bacterial infections contracted from either the dermatitis or feet problems and that spread rapidly through the bloodstream despite aggressive treatments with antibiotics and fluids.

As of March 25, the team has successfully kept eight bats alive in the colony.

The Findings

Although the "bat team" knew the high risks associated with this effort, no one had ever attempted to scientifically assess and sustain this subspecies of bat in captivity. So we have learned new, important information about the Virginia big-eared bat, and can share and advise the larger scientific and conservation community about security populations. 

The Bigger Picture

As was predicted, white-nose syndrome continues to wipe out wild bat populations. It has been confirmed that the fungus is present in Hell Hole Cave in West Virginia, which is near the original home of our bat colony. Although the syndrome has killed significant numbers of little brown bats (Myotis lucifugus) in that exact cave, the Virginia big-eared bats are still alive. That news is encouraging to our colleagues at the U.S. Fish & Wildlife Service and is buying researchers time to learn more about the bats and disease.

Meanwhile, this winter, white-nose syndrome reached Tennessee, a state where large populations of two other endangered bat species (Indiana and gray bats) live. State and federal agencies are surveying caves in eastern Tennessee as part of white-nose syndrome monitoring.

Scientists are searching for a way to stop the spread of this disease and develop a rapid diagnostic test. Last year the U.S. Fish and Wildlife Service funded five research projects, in addition to our own, focused on white-nose syndrome and bat survival.

Share