Pigs to the rescue: An invasive species helped save Australia’s crocodiles

Despite such adaptations and dietary changes among apex predators, invasive species are still gaining ground. In Australia, for example, the country’s then-commissioner for endangered species told the national broadcaster in 2015 that “Australia has lost 29 mammals since European colonization, and wild predators are involved in 28 of those extinctions.”

Florida faces similar invasion problems as it hosts an ideal combination of a subtropical climate, a thriving pet trade, and multiple ports of entry. The result, said Ian Bartoszek, a wildlife biologist at the Conservancy of Southwest Florida, is that the state “has more established non-native animal species than any other country in the world.” Or, like Dr. Mazzotti said of the Everglades, “I’m preparing to call it Everglades Invasive Reptile National Park.”

Even in the Everglades there is good news. As Burmese pythons eat their way through the Everglades’ medium-sized mammals that eat reptile eggs, Mr. Bartoszek said it’s possible that loggerhead turtles and the endangered American crocodile could benefit.

The effects on alligators are less clear. Although there is no data to confirm this yet, “it feels like the alligator is holding the line, and the alligator is most likely responsible for more python predators than we gave them credit for,” Mr. Bartoszek said. “The python has found its niche in the swampy areas and in areas that don’t have any permanent bodies of water where alligators don’t patrol. But in these deeper, more permanent areas of water, I think the alligator has settled on the python and is definitely doing us a service here.”

These are relatively small victories so far in the broader effort to control invasive species. According to Mr. Bartoszek, 47 species of birds, 24 species of mammals and two species of reptiles have been found in the bellies of pythons.

And in the United States, like Australia, it will take more than crocodiles and alligators to contain such pests. Much remains uncertain as to where apex predators feed on invasive species. “Are there clear examples where a single species can and has benefited from an invasive species? You can bet on that,” said Dr. Mazzotti. “What are the other implications? We’re a lot less sure about that.”

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