Wildlife Corridors Can Encourage The Spread Of Invasive Species Such As Fire Ants

Wildlife corridors, whose purpose is to increase biodiversity by linking different wildlife habitats separated by human activity, can also act as a type of super highway to assist in the spread of invasive species, according to a new study.

A team of researchers at the University of Florida found that a type of fire ant used wildlife corridors to take over new landscapes. The findings are particularly relevant to Florida, where invasive species, such as Cuban tree frogs, green iguanas and feral hogs are considered to be a serious ecological problem, according to the study, which was published in the August issue of the journal Ecology.

“Although habitat corridors are usually beneficial, they occasionally have negative effects,” Julian Resasco, the study’s lead author, said in a statement. “Sometimes they can help invasive species spread in exactly the same way they help native species.”

The researchers said they were initially surprised by the findings because it is assumed that invasive species are adept at dominating new areas without the help of corridors to get around. Resasco and his team studied eight sections of land in South Carolina, each dominated by one of two social forms of fire ants -- monogyne and polygyne.

“Each section consisted of five patches of regenerating habitat. Each patch was about the size of a football field,” the researchers said. “Some were connected by a corridor and others were not, allowing the researchers to study the influence of corridors.”

The researchers found that the presence of the corridors significantly increased the population of polygyne fire ants, which mate closer to the ground and sometimes travel short distances to create new colonies. The researchers also found that, due to the higher number of fire ants, the diversity of native ant species was lower in polygyne patches connected by corridors.

“It is not a coincidence that the readily dispersing monogyne form of fire ants doesn’t benefit from corridors, whereas the poorly dispersing polygyne form does,” Resasco said.

The latest findings are reported at a time when a team of explorers prepares to begin a 1,000-mile expedition to raise support for the Florida Wildlife Corridor, whose goal is to create a strip of land stretching from Everglades National Park to the Okefenokee National Wildlife Refuge in Georgia.

However, Resasco urged land managers to consider the traits of local fauna before making decisions about land corridors.