Iowa State University Alumni Association| online edition | spring 1999

SPRING 1999
Home

Cover Story:
The Bells of Iowa State

Feature:
Driving Dr. Carver

Departments:
Getting Started
Letters
On Campus
Alumni Profile
College Focus
Discovery
Association News
Giving
Sports

PRESERVING NATURE'S NIGHT CREATURES

Vampire bats are not cute or cuddly. They fly at night, feed exclusively on blood, and often spread disease. So it's no wonder they have a bad reputation and that farmers and ranchers have been trying to wipe out the species for nearly a century.

What is surprising, however, is the almost human way vampire bats stick up for one another and how they have survived – even flourished – as a species, in the face of unrelenting environmental obstacles.

“They should not exist,” says third-year veterinary student Lisa De Nault, speaking in terms of evolution. “They’re such oddballs. They feed exclusively on blood, they have to feed every 36 to 48 hours or they’ll die, and they can only live in the tropical climates found in Central and South America.”

De Nault is fascinated by the social nature of the much-maligned vampire, asserting that they’re “fabulous” to watch as they exhibit their characteristic social grooming and foodsharing behaviors.

But rabies is a major threat to the vampire bat population, and in turn, the disease is spread to herds of cattle, wildlife, and even humans as the bats seek a food source. Since the 1920s, vampire bats have been threatened by poison and other methods of extermination to no avail. The species thrives, the disease continues, and rural Central and South Americans suffer the loss of a hundred thousand cattle each year.

De Nault became interested in bats when she was an undergraduate in California, studying the creatures’ feeding and migration patterns. At Iowa State’s Depart ment of Veterinary Microbiology and Preventive Medicine in the College of Veterinary Medicine, De Nault is conducting a full-blown graduate research project. Her goal? Wipe out rabies in the vampire bat population without harming the bats.

Her method is based on the social grooming she observed as an undergraduate. Like a mother cat bathing her kittens, vampire bats lick and groom their roost mates for up to eight hours a day. De Nault’s study theorizes that if five to ten percent of the vampire bat population could be caught and baited with a jelly-like recombinant rabies vaccine smeared around their mouth or neck area, the vaccine would be shared with the rest of the population through social grooming.

There is much work to be done before the theory can be tested in the field. De Nault first must prove that the oral vaccine will produce enough antibodies to combat rabies, and then that the vaccine can successfully be shared between roost mates.

De Nault conducts her research on four female vampires housed in a tropically hot, humid room in the Animal Holding Facility at ISU’s vet med complex. Wearing heavy leather gloves, she cradles one tiny snub-nosed creature she fondly calls “Angelina.” The bat screeches but is surprisingly relaxed while being handled. De Nault says that’s typical vampire bat behavior.

“Most bats instinctively try to wiggle away when they get caught,” De Nault explains. “But vampires will actually stop and just sit there and stare at you. I thought it was really creepy at first.”

Of all the unusual characteristics of vampire bats, De Nault finds their life-sustaining practice of foodsharing the most amazing. The behavior goes like this: When a member of the vampire bat colony has an unsuccessful night of feeding – meaning that it was unable to secure a blood meal – it is at risk of dehydration, which will become life threatening after 48 hours. So the unsuccessful “solicitor” begins a pattern of behavior with a “donor” roost mate that involves licking it around the mouth and chirping. The donor responds by regurgitating part of its own blood meal to allow the less fortunate bat to get by for another 24 hours – and very possibly saving its life.

It’s a behavior that De Nault says is completely unique to vampire bats and probably accounts for the survival of the species. “You see maternal foodsharing behavior in many species, and some species such as lions and wolves will kill prey and share it – but it’s always with family members that are genetically related. The cooperation among genetically unrelated vampire bats is unique among mammals.”

If De Nault’s research is successful, it could stem the tide of bat-transmitted rabies in Central and South America. Vaccinating the bats against the disease makes sense, De Nault says, especially when attempts at destroying the bat population are not working.

“The current controls aren’t working, obviously, because outbreaks of rabies continue in livestock and in humans,” De Nault says. “It’s a public health threat.

“I also look at it as a conservation issue because a lot of beneficial bats are being decimated because of this problem. Maybe there’s a different way to go.”

About the Writer | Carole Gieseke is the editor of VISIONS magazine.