Burmese pythons (Python molurus bivittatus) established what was thought to be isolated breeding populations in the Florida Everglades a few decades ago. Now concern is rising that the python invasion could spread to the Florida Keys and other islands in the Caribbean. Hatchlings, it turns out, are saltwater swimmers.
"Because reptiles, in general, have poor salinity tolerance, it was hoped that salt water would naturally hinder pythons' ability to expand their range beyond the Everglades," said Kristen Hart, a US Geological Study research ecologist who led a recent study of pythons' tolerance to salt water.
"Unfortunately, our results suggest salt water alone cannot act as a reliable barrier to the Everglades python population," she said in a press release.
Burmese pythons are one of the world's largest snakes and can grow to over 4 meters (13 feet) long. The massive constrictors are native to Southeast Asia, but came to the US as pets. Escaped and intentionally released pet pythons found a hospitable habitat in Florida's swampy wilderness.
Alligators, and a few other predators can eat small pythons, but large adults have no enemies besides humans.
"The fact that this study has ruled out one of the most hoped-for forms of physical barriers, salt water, as preventing the spread of invasive pythons in Florida puts even more onus on human action to prevent the spread of these damaging reptiles," explained USGS director Marcia McNutt.
The study was published in the Journal of Experimental Marine Biology and Ecology.
A Burmese Python, Python molurus bivittatus (Karunakar Rayker, Wikimedia Commons)
A Burmese python (Python molurus bivittatus) peeks over the head of an alligator that holds the python's body in its mouth in Everglades National Park. (Lori Oberhofer, National Park Service)