Cotton rats can carry nasty diseases that can infect humans.
Jeremy Woodhouse/Getty Images
Burmese pythons are killing off mammals that would normally keep Florida’s rat population in check.
As a result, parts of the Florida Everglades are becoming overrun with rodents, a new study found.
It may be good news for the cotton rats, but it could spell serious danger for humans.
Florida’s Burmese pythons have been known to prey on birds, reptiles, deer, and even alligators. But one thing they don’t seem to have a taste for is cotton rats.
And the rats are thriving because of it.
So much so, scientists warn that cotton rats “now dominate the community” in parts of the Florida Everglades where pythons are prevalent, wildlife ecologist Robert McCleery told LiveScience.
McCleery and a team of colleagues measured this unusual relationship between python prevalence and cotton rat population in a new study published in the Journal of Mammology.
Pythons are helping cotton rats take over
For the study, McCleery and colleagues tracked 115 rats, via radio transmitters they attached, in both regions with high and low python populations.
They found that death rates for cotton rats were about the same in both regions. And the pythons themselves were only responsible for about 12% of rat deaths.
Instead, what was killing and consuming most of the rats were the usual suspects: birds of prey, mammals, and other reptiles. The plot twist here is that pythons are snacking on the same animals that enjoy cotton-rat dinners.
As a result, the number of predators cotton rats face is declining and will likely continue to do so if Florida’s invasive python problem persists, the scientists warn.
Florida has a serious invasive python problem
A Burmese python sits in the grass at Everglades Holiday Park in Fort Lauderdale, Florida on April 25, 2019.
Rhona Wise/AFP via Getty Images
Burmese pythons aren’t native to Florida, they’re actually native to southeast Asia.
They became pests in Florida when people brought them overseas during the exotic pet trade industry in the 1980s and then later released them into the wild. The snake’s numbers have been steadily growing ever since.
It’s gotten so bad that Florida holds an annual Python challenge that awards thousands of dollars and cash prizes to people who can catch and humanely kill the most pythons.
Florida’s python infestation has thrown Florida’s delicate ecosystems off balance and led to severe declines in mammalian populations, including raccoons, opossums, bobcats, foxes, and cottontail and marsh rabbits.
The snakes “are one of the most concerning invasive species in Everglades National Park,” the US Geological Survey said.
And McCleery and his team are seeing the rippling effects cascade down the food chain.
Without predators like foxes to hunt cotton rats, this “helps explain why mammal communities in python-invaded portions of the Greater Everglades Ecosystem are increasingly dominated by cotton rats and other rodents,” the researchers reported in the study.
Cotton rats carry concerning diseases
While all of this seems like good news for Florida rodents, it could spell bad news for residents, because rats are notorious for carrying nasty diseases that can infect humans.
Let’s say a mosquito bites an infected cotton rat and then later feasts on your blood — you could become infected. And the diseases that cotton rats can carry are no fun. They include hantaviruses and the Everglades virus.