Nearly 100 fossil species pulled from a flooded cave in the Bahamas reveal a true story of persistence against all odds -- at least until the time humans stepped foot on the islands. University of Florida researchers say the discovery, detailed in a study appearing in the Proceedings of the National Academy of Sciences, shows many human activities pose a threat to the future of island biodiversity, with modern human-driven climate change not necessarily the most alarming. A new $375,000 National Science Foundation grant will allow further exploration of caves on Caribbean islands beginning in December. 

Thirty-nine of the species discussed in the new study no longer exist on Great Abaco Island in the Bahamas. Of those, 17 species of birds likely fell victim to changes in climate and rising sea levels around the end of the Ice Age, about 10,000 years ago. Twenty-two other species of reptiles, birds and mammals persisted through those dramatic environmental changes only to vanish when humans first arrived on the island 1,000 years ago.

Exploring why some species were more flexible than others in the face of climate and human-driven changes could alter the way we think about conservation and restoration of species today, when scientists fear activities like habitat alteration and the introduction of invasive species could pose the greatest risk to island species, said lead author Dave Steadman, ornithology curator at the Florida Museum of Natural History on the UF campus.

"What we see today is just a small snapshot of how species have existed for millions of years," Steadman said. "The species that existed on Abaco up until people arrived were survivors. They withstood a variety of environmental changes, but some could not adapt quickly or drastically enough to what happened when people showed up. 

"So, there must be different mechanisms driving these two types of extinctions. What is it about people that so many island species could not adapt to? That's what we want to find out."