for National Geographic News
Vampire bats in Latin America are turning their fangs on cattle as rain forest is being cleared to make way for livestock, new research shows.
Scientists made the find by studying changes in the breath of vampire bats in Costa Rica.
The researchers discovered that the bats are finding meatier victims to sink their fangs into as the habitat of wild forest mammals disappears and is turned into livestock pasture.
A study led by Christian Voigt from the Leibniz Institute for Zoo and Wildlife Research in Berlin, Germany, found the blood-seeking bats are switching to cattle from rain forest prey such as tapirs and piglike peccaries.
The study team investigated which animals the bats were targeting by analyzing the chemical signatures, called isotopes, in the carbon dioxide they exhaled soon after eating.
Cattle and rain forest mammals feed on different plants that can be distinguished by their carbon isotopes. Since these chemical clues are present in prey's blood, the signature in the bats' breath varies with their meals.
The study clearly indicated that the vampires' most recent victims were almost always cattle, the team said.
The findings don't mean that vampire bats prefer bovine blood, the team said. Instead, they suggest that livestock are simply easier for the bats to find.
Voigt compared the vampire's dining options to that of a hungry human looking for a hot dog.
"One supplier is moving with a small van through the streets of the town, and it is not predictable for you where the van shows up," he said.
"The other supplier is in a snack bar with a permanent address. You most likely wouldn't go searching [for] the hot dog van but [would instead] go to the snack bar. Vampires are basically doing the same."
Vampires on the Rise
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