The research, which is published online in the Journal of Comparative Physiology B, came in response to reports from Costa Rican cattle ranchers of increased vampire attacks in the region.
Only three bat species are vampires, all of which are confined to Latin America. Just one of these, the common vampire bat, feeds on mammal blood.
Attacking at night, the bat doesn't suck its victims' blood but laps it up from tiny puncture wounds made with two sharp fangs. An anticoagulant in the bat's saliva keeps its nutritious meal from clotting.
Anecdotal evidence suggests that vampire bat numbers have increased significantly over the past 50 years, Voigt said.
This rise is widely attributed to deforestation, a theory bolstered by recent surveys of bat populations conducted by Voigt's team, he added.
A survey in virgin rain forest in the remote Amazon detected only a few vampires, Voigt said, but a survey of disturbed rain forest in the Andean foothills showed the winged blood-seekers to be the most abundant bat species.
No livestock were found near the Amazonian site, Voigt said, "whereas at the other site numerous pastures with cattle were present."
Livestock farming is seen as a leading cause of rain forest destruction in Central and South America.
(Related: "Amazon Deforestation Drops 25 Percent, Brazil Says" [August 14, 2007].)
In the Amazon, around 60 percent of deforestation between 2000 and 2005 can be attributed to cattle ranching, according to estimates based on figures from the Brazilian National Institute of Space Research and the United Nations Food and Agriculture Organization.
The growing number of vampire bats in cattle-ranching areas has also been blamed for the spread of disease among both humans and domesticated animals.
In just two months in 2005, 1,300 people in northern Brazil were treated for rabies after suffering bat bites. Twenty-three of the patients died, according to reports.
Voigt said that habitat conservation, along with efforts to reduce wildlife poaching, is crucial to minimizing the overall impact of vampire bats and their late-night raids.
"If rain forest mammals such as tapirs and peccaries are killed, there is no alternative left for vampires to get blood from," he said.
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