Non-native prey may supplement the diet of native predators, but they do not replace native prey species as a food source.
Researchers at Ohio State University studying interactions between predator and prey species have discovered that the predator populations increased over 57 percent when new invasive species were present.
The problem is, the numbers only stayed that way when their native prey stayed abundant.
Assistant professor of aquatic ecology at OSU, Lauren Pintor said "Eating non-native prey isn't as good for predators as eating native prey. It may be that the new prey isn't as nutritious, or that the predator hasn't evolved the ability to eat or digest it well."
One of the few success stories comes from the Lake Erie watersnake and its new taste for one invasive species.
After finding itself on the endangered list this Midwestern reptile has bounced back in numbers, upgrading its status, thanks in part to the invasive round goby.
The goby is a European bottom-feeding fish said to have emerged in the Great Lakes through ballast dumps by ocean-going vessels.
The Lake Erie watersnake has grown accustomed to eating this invasive fish and using it as a prime food source.
Pintor is cautious though:
"We want to caution that while we might see an increase in population abundance and density among some native predator species, that's not always a good thing, either. There could be unintended consequences for other native species."
She went on to say: "But in all these studies, whenever predators' diets were restricted to non-native prey, the predators did not perform as well as they did on native prey."