Among the primary goals for implementing wildlife corridors is to boost biodiversity and protect animals from becoming endangered due to human activities such as the development of roads and buildings.
A new study, however, suggests that while wildlife corridors, e.g. areas that are intended to reconnect habitats that are separated by agriculture and other human activities, could be helpful in wildlife conservation, they also come with unwanted consequences such as encouraging the spread of invasive species.
For the study published in the August issue of the journal Ecology, Julian Resasco, from the Department of Biology of the University of Florida in Gainesville, and colleagues found that wildlife corridors promote the spread of a type of invasive fire ant.
"Although habitat corridors are usually beneficial, they occasionally have negative effects," Resasco said. "Sometimes they can help invasive species spread in exactly the same way they help native species."
Most species of fire ants are neither harmful nor invasive but the researchers focused on the invasive Solenopsis invicta, also known as red imported fire ant, or RIFA, because it is responsible for the displacement of native ants and is considered as one of the most harmful and most invasive species in the U.S. The U.S. Food and Drug Administration estimates that over $5 billion is spent each year because of RIFA infestation.
Resasco and colleagues looked at the effects of wildlife corridors on ant communities specifically on the two social forms of fire ant, the polygyne and monogyne. The colonies of monogyne fire ants only have one egg-laying queen whereas polygyne colonies have several egg-laying queens. The ecological effects of polygyne fire ants also tend to be more severe when compared with the monogyne ants. Invasion of polygyne ants can likewise devastate native ant communities while invasion of monogyne ants has benign effects. Unlike monogyne ants, however, that fly to disperse and mate, polygyne ants crawl and cover only short distances which is why they do not spread widely.
By studying eight section of land in South Carolina, the researchers found that wildlife corridors have significantly increased the number of polygene fire ants but did not have effect on monogyne fire ants and this apparently has something to do with the corridors affecting the dispersal ability of ant communities.
"With invasive species that are dispersal limited (but successful by other measures), corridors are likely to facilitate spread and could result in a net negative impact on native species," Resasco and his colleagues wrote, adding that further studies on species with different dispersal abilities and different habitats could provide further information on when wildlife corridors are most likely to induce the spread of invasive species.
