Linked habitats, meant to help in wildlife conservation, do have a downside, researchers say, when they allow the easy spread of less-than-desirable invasive species.

One example is a type of invasive fire ant in South Carolina that used wildlife corridors linking habitats as a highway to move into and dominate newly created landscapes, researchers say.

Although invasive species usually have no trouble spreading into new areas with or without corridors, the researchers say their study proves an old axiom suggesting animals will follow the path of least resistance when one is available.

"Although habitat corridors are usually beneficial, they occasionally have negative effects," says study leader Julian Resasco of the University of Florida. "Sometimes they can help invasive species spread in exactly the same way they help native species."

Resasco and his research team traveled to South Carolina to study eight sections of land dominated by fire ants.

Each section held of five patches about the size of a football field of regenerating habitat, with some connected by a wildlife corridor and some not.

That allowed the team to examine the influence of corridors on the ants' movements.

Fire ants possessing two different social forms were examined. One, so-called monogyne fire ants that fly high into the air to mate and disperse, coming back down to ground to form new colonies, and the other, polygyne fire ants which mate on the ground and only crawl short distances to form new colonies.

The dispersal ability of each of the forms determines whether corridors can spread the invasive insects, Resasco says.

"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," he says.

The study suggests that invasive species that might otherwise take considerable time to advance into new habitat may take advantage of corridors created with benefits to native species as their intent, he says.

Such studies are particularly relevant to Florida habitats, the researchers said, where invasive species such as Burmese pythons, Cuban tree frogs, feral hogs and green iguanas are a difficult and ongoing problem.

Land managers need to consider animals' behaviors and traits when making decisions about providing land wildlife corridors, Resasco says, because in some cases corridors created with the best of intentions for native species could backfire be creating wide-open avenues for invasive species to, well, invade.