UF Researcher: Humans Make Extinction Happen 100 Times Faster

March 6, 1997

GAINESVILLE — Extinction is a natural process, but human activity can make it happen about 100 times faster, a University of Florida professor has discovered studying fossil records on South Pacific islands.

After spending 20 months of the last 12 years on more than 100 South Pacific islands studying fossil records and other data, David Steadman, assistant curator at UF’s Florida Museum of Natural History, can show the effects human actions have had on island birds, which in turn affected other wildlife.

“One way to look at this is that under natural conditions we might lose a species once every 1,000 years,” Steadman said. “And after people are introduced the rate is increased to one species every 10 years, which in terms of evolution is a disaster.”

Other regions have seen similar and sometimes greater reductions in species.

“I studied the Hawaiian Islands for 20 years and found basically the same thing, except perhaps more dramatically so because of the more diverse fauna,” said Storrs Olson, curator at the Natural History Museum at the Smithsonian Institution in Washington, D.C. “So 100 times seems like a fair number. These ecosystems are usually pretty stable until people enter the scene.”

Steadman worked mainly on the Cook and Tonga islands, where he found patterns of extinction that hold true throughout the island world.

“All humans have a significant impact on the environment, regardless of technology, race or culture,” Steadman said. “No one can claim to live harmoniously with nature. This doesn’t mean we should throw up our hands and give up, because now we have more of an obligation to be responsible.”

Even the Stone Age people who came to these islands 3,000 years ago had an effect, Steadman’s work shows. They cleared land, introduced other animals into the environment and trapped native birds for food.

“This can be seen through studying bones at archeological sites, identifying them and tracing the changes in fauna through time,” Steadman said. “Changes in vegetation can be seen through pollen records taken from lakes. Cores of mud are taken from the lakes, and the segments are analyzed to show what pollen and seeds were present at a particular period.”

Before humans arrived, the islands were dominated by forest. After human activity reduced the number of birds, the forest trees declined and the vegetation became dominated by grasses, ferns and other nonwoody plants.

“One important factor is that a lot of these plants depended on birds to disperse their seeds or to pollinate the flowers,” Steadman said. “Once the birds became extinct, nothing was left to distribute seeds. This, along with people cutting and burning, led to the decline of the forests.”

Steadman said his research is useful for conservation measures, such as creating bird sanctuaries on islands where a species lived before being exterminated by humans.

“Knowing the natural distribution of these birds can help us understand where they may be reintroduced,” said Olson. “In Hawaii, the Hawaiian goose has been reintroduced on the islands of Kauai and Maui, islands where there were large populations of the birds before humans.”

The species that survived on these islands had to adapt quickly to the changes humans introduced. Although human involvement directly or indirectly exterminated many animals, human intervention might help preserve some endangered species.

“The biggest thing we can do to preserve a species is preserve a number of habitats and keep them in good shape,” Steadman said. “Once species become endangered, we need to make changes. In the past, these early people hunted these birds, they didn’t stop and the birds became extinct. Now, if we can see that a species is in a big decline, we need to study why this is and make appropriate changes or we will lose the species.”