Wildlife Corridors May Encourage the Spread of Invasive Species Across States

Wildlife corridors may be helping animal migrations, but they could also be helping invasive species. Scientists have found that wildlife corridors, which are strips of natural land created to reconnect habitats separated by human activities, can sometimes encourage the spread of non-native species.

These findings have particular importance for Florida, where invasive species are a massive problem. Everything from Cuban tree frogs to green iguanas to feral hogs to pythons has invaded this state. Even coastal waters aren't safe; lionfish have invaded Florida's coral reefs.

Habitat corridors were first created in order to allow native species to journey between fragmented habitats. Yet giving them ease of movement may also give invasive species the same opportunity.

"Although habitat corridors are usually beneficial, they occasionally have negative effects," said Julian Resasco, one of the researchers, in a news release. "Sometimes they can help invasive species spread in exactly the same way they help native species."

In order to study how environmental corridors might influence the spread of invasive species, the researchers looked at fire ants. These insects have two social forms: monogyne and polygne. Monogyne fire ants fly high in the air to mate and disperse, while polygene fire ants mate low to the ground and crawl short distances to form new colonies.

The scientists examined eight sections of land, each dominated by one of two social forms. In the end, they found that corridors significantly increased the abundance of polygne, but not monogyne, fire ants. In fact, in polygyne sections, native ant species' diversity was lower in 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 polygne form does," said Resasco.

The findings reveal that invasive species that are normally poor at dispersing can take advantage of these wildlife corridors. This means that officials should take note of where these corridors are placed, and which invasive species could benefit.

The findings are published in the journal Ecology.