Mammal populations in certain areas of Florida are declining, according to one report. The cause? Giant snakes.
The Burmese python (Python molurus bivittatus) is a large constricting snake, native to northeast India, southern China, and southeastern Asia. It doesn’t occur naturally anywhere near the United States, but it’s estimated that more than 300,000 of the snakes have been imported into the U.S. in the last 30 years by the exotic pet trade. When they grow too large to handle, the snakes — known for their docility under normal circumstances — are often released into the wild by pet owners. An adult Burmese python can measure up to 5.5 metres. One individual over 4.9 metres (16 feet) long was captured just last month.
A new report in Proceedings of the National Academy of Sciences (PNAS) shows that mammal populations in the Florida Everglades, as measured by roadside surveys, have shown dramatic declines in the last eight years. The surveys, which covered 56,971 kilometres of roadway in and around the Everglades National Park, observed a decline of 99.3 per cent, 98.9 per cent, and 87.5 per cent in raccoons, opossums, and bobcats, respectively. No rabbits were observed during the recent surveys.
It’s not all because of predation, though. It’s difficult for scientists to be sure which animals are being killed by the pythons and which ones are competing for the same resources. But there’s no doubt that P. molurus is an ambitious species. The United States Geological Survey, which contributed to the PNAS report, has observed the snakes fighting with alligators.
There is even a picture of a python whose belly had burst after eating an alligator. It’s uncertain whether the bursting was due to the alligator attempting to escape the snake’s stomach or a simple buildup of gases, but the image is genuine. Florida’s Burmese python problem has been particularly hard on endangered species such as the Key Largo woodrat. Researchers were tracking down a tagged woodrat in 2007, and found it in the stomach of a seven-foot python. The snake’s stomach also contained a second woodrat.
The pythons are particularly hard to eradicate because they are extremely adaptable creatures. Throughout Asia they live in many different habitats and are capable of living on a wide variety of diets. They move very rarely between hiding spots, which makes them difficult to trap, and they breed at startling rates. They are capable of producing clutches of up to a hundred eggs at a time — as a result pf these factors the python population in the Everglades is estimated to be between 30,000 and 100,000.
Invasive snakes may not be easy to stop, but conservation groups and the U.S. National Parks Service are going to try. The Everglades NPS has a beagle named “Python Pete,” who is trained to sniff out the snakes. In an attempt to prevent the snakes from spreading to the Florida Keys and breeding, the Nature Conservancy has been training FedEx and U.S. Postal Service employees in spotting Burmese pythons, which often warm themselves on the road. There is even a hotline citizens can call to report python sightings.
Trained python responders can then be dispatched to collect the rogue reptiles. There are a number of techniques used to trick the python into tiring itself out so it can be easily captured. One is called “treadmilling,” in which the catchers drag their hands along the snake’s belly to make it think it’s escaping. Since the year 2000, over 1,800 snakes have been removed by the National Parks Service in the Everglades.
The snakes, though, may already be permanently entrenched in the Everglades. A severe freeze in early 2010 failed to do more than put a dent in python populations. Further efforts may consist of making sure the current problem doesn’t get any worse. But at least there’s a bright side: the Burmese python is not known to be aggressive towards humans.