Burmese pythons have a remarkable ability—similar to that of the famous homing pigeon—to find their way back home.
Pythons that were captured from Everglades National Park, placed in opaque containers, loaded onto vehicles, and moved as much as 36 km returned to within 5 km of their original location, researchers found. A study published in the March edition of the Royal Society Publishing journal Biology Letters shows that the snakes’ movement indicated they definitely knew where they were going.
The researchers say the results give clearer evidence that Burmese pythons have navigational map and compass senses.
When University of Florida Wildlife Ecology Professor Frank Mazzotti and colleagues captured the snakes in Everglades National Park to study the animals’ movement and use of habitat, park officials wouldn’t let them return the pythons to the park, where they cause trouble for native species (usually by eating them). Nevertheless, when the scientists moved the fearsome creatures beyond park boundaries, the snakes turned around and headed home. This was in contrast to a control group that was driven around in circles and returned to near their spot of capture; those snakes mainly just chilled out around home, moving more slowly and not nearly as far.
The finding could help combat the spread and environmental impact of the pythons, an invasive species in South Florida that grows up to 13 feet and numbers into the hundreds of thousands, experts estimate. “A better understanding of movement behavior will help managers to better predict and prevent population expansion,” said Davidson College postdoc Shannon Pittman, a coauthor of the study.
These snakes, one of the five largest in the world, have contributed to the documented decline of mammal populations—some of them endangered—in the Everglades after being kept as pets and then released or escaping. A 2011 study in the Wilson Journal of Ornithology found 25 species of birds, including the endangered wood stork, in the digestive tracts of Burmese pythons at Everglades National Park. In one effort to reduce the Burmese python population, the Florida Fish and Wildlife Commission last year launched its first-ever Python Challenge, with more than 1,500 hunters from 38 states signing up to hunt Burmese pythons. The event, which the state does not plan to repeat, led to the capture of a measly 68 pythons.
The scientists tracked the movements of 12 adult Burmese pythons, releasing six of them 21 km to 36 km from their original capture locations and the other six at the location where they were previously captured, using them as a control group. The snakes released far away from home were put under an anesthetic, implanted with a radio transmitter, and then tracked using a GPS from a small aircraft one to three times a week.
To the surprise of researchers, who had initiated the study to answer general questions about movement and habitat, all of the relocated pythons’ movements were in the direction of their release point, with five of the six reaching within 5 km of their capture location. Their compass-like sense has implications for “predictions of spatial spread and impacts as well as our understanding of reptile cognitive abilities,” the authors wrote.
One challenge researchers faced was the limitations in detecting the pythons, which would have increased their sample size and brought in more encompassing results.
“We detected a very, very small portion of the ones that are out there," said Mazzotti. “That’s why if you have 1,500 people hunting snakes, as they did in the challenge, they only turned up 68 in a month.”
Mazzotti, who is part of the Croc Docs team at the University of Florida, said that unlike American crocodiles, “who have eyes that shine like bicycle reflectors,” snakes are difficult to spot and collect.
“It’s an animal that is camouflaged, secretive, and you don’t know where it lives,” he said.