Fossils Link Caribbean Bat Extinction to Humans, Not Climate Change

by AMNH on

Research posts

A major change in climate after the end of the last ice age was not the primary cause of extinction of Caribbean bats, a new study led by the American Museum of Natural History and the University of Florida has found. The Caribbean’s first humans may have been responsible for the winged mammals’ disappearance instead.

The new research, published this week in Scientific Reports, rejects previous studies that directly connected climate change and related loss of land with the disappearance of bats, pointing to humans’ arrival as a potential catalyst for the group’s extinction. Knowing when and how Caribbean bats went extinct could help save modern-day wildlife from meeting the same fate.

Lead author J. Angel Soto-Centeno displays the fossilized skull of a Cuban fruit-eating bat (Brachyphylla nana).
© AMNH/J.A. Soto-Centeno

“Prehistoric and modern humans have had considerable impacts on island species and ecosystems,” said lead author J. Angel Soto-Centeno, a post-doctoral researcher at the American Museum of Natural History who began the study as a doctoral student at the Florida Museum of Natural History on the University of Florida’s campus. “We found that the demise of bat populations in the Bahamas coincides with similar land mammal, reptile, and bird losses on other Caribbean islands.” 

Twenty-five thousand years before people set foot on the pristine beaches of the Bahamas, the world was a colder place. When the planet began to warm after glaciers covering much of the Earth melted and sea levels rose, large islands quickly became small islands.

University of Florida ornithology curator David Steadman collects fossils inside a cave on the Bahamian island of Abaco. 
© AMNH/J.A. Soto-Centeno

Soto-Centeno and David Steadman, curator of ornithology at the Florida Museum of Natural History, performed radiocarbon dating on fossils of nine species of living and extinct bats from the Abaco islands. Their results demonstrate that at least five species of bats withstood climate change and reduced land area, only to be wiped out around 4,000 years ago, when climate conditions were largely similar to those of today.

“Ours are the first radiocarbon dates for bat fossils in the whole West Indies,” Steadman said. “The new dates prove that certain bat populations were still in existence much later than previously thought—around the same time humans arrived. 

The findings imply that the cause of bat population loss in the Caribbean is more complex than previously thought.

“Now that we have the technology to date these small bones, it opens up the possibility of determining the chronology of the extinction of bats in the Caribbean,” Steadman said. “We have good evidence that it is not the shrinking of islands that wiped out these populations, and the only thing we know happened in the last thousand years that might affect bat populations is the arrival of people.”