A new review is the first to describe the scope of threats to bats by invasive species.

The review summarizes the threats according to four categories: predation, disease, competition, and indirect interactions. The investigators identified threats of 37 invasive species to 40 bat species. Ten bat species were threatened by more than one invasion pathway. About 38 percent of cases are speculative and 18 percent circumstantial, and most accounts do not provide enough information needed to forecast bat population impacts.

Over 60 percent of bat species reviewed are island dwelling, corresponding with evidence indicating that most extinctions occur on islands and that invasive species' impacts are worse for island than mainland populations.

"Evidence of cat predation was the most frequently cited threat. But the most interesting threat to me involved invasive burdock, a plant with prickly flower heads with hooked bracts, that entangle bats," said Dr. Jessica Nicole Welch, co-author of the Mammal Review study.

"We often think of the impact that bats have on invertebrates that transmit disease to humans, like mosquitoes, but it is much less broadly known that venomous giant centipedes kill bats and competition from cavity nesting, feral honeybees, and little fire ants exclude bats from tree hollows where they raise their young," added co-author Dr. Christy Leppanen.