March 20, 2014
Amazing Homing Abilities Revealed In Burmese Pythons From Florida
Lawrence LeBlond for redOrbit.com - Your Universe Online
South Florida has been dealing with a problem of epic proportions in recent years: an invasion of Burmese pythons. According to the National Park Service, more than 2,000 pythons have been removed from the Everglades since 2002, with experts calling this just a small fraction of the total population now found there.
While this in itself is a significant problem for Southern Florida, new research published in the journal Biology Letters could complicate the situation even further.
Shannon Pittman, a post-doctoral fellow in the lab of Professor of Biology Mike Dorcas at Davidson College, is the lead author of a new study that uncovers some amazing homing abilities found in Burmese pythons. Pittman first visited the Everglades during her freshman year at Davidson with Dorcas and a team of herpetologists.
"What we found was an ability of these snakes to travel in straight paths all the way back to their point of capture," Pittman said in a statement, noting that this has implications for the spread of the species.
Pittman explained that homing requires a map sense that allows the animal to determine its position in relation to its goal; also, a compass sense is needed so that it can maintain orientation toward that goal. In the snakes that were relocated, the study team found that these pythons had the ability to travel in near-straight paths back to their point of capture, indicating that they do carry this homing and compass sense. The team said these snakes not only found their way home, but also move faster and straighter than snakes that were not relocated.
In all, six Burmese pythons that were relocated to between 13 and 22 miles from their capture locations, headed straight back home to the Everglades, navigating to within three miles of their original capture point.
"Previous studies have shown that many snakes lack the ability to home, yet this study provides evidence that Burmese pythons are capable of homing after they have been displaced – and they are able to do so at a scale previously undocumented for any snake species," said Pittman. "Understanding this large-scale navigational ability is critical to understanding the ability of Burmese pythons to expand their geographic range."
The team also found what seemed to be local cues that helped the snakes determine their position relative to their home location. Pittman and colleagues think the cues underlying the map sense may be olfactory or magnetic that change predictably through space. As for the compass sense, the team said the snakes navigate based on magnetic, celestial, olfactory or polarized light cues, all of which are reliable cues for navigation.
"The snakes maintained their oriented movement over the course of a relatively long time, between 94 and 296 days," said Kristen Hart, a USGS researcher and study coauthor. "This indicates that not only do pythons keep their long-term movement goal in mind, but also that they were highly motivated to get back home."
Burmese pythons of course are not native to Florida. The invasive species is believed to have been inadvertently introduced to the Everglades by the accidental or purposeful release by former pet owners, with the first account of these snakes being reported in the region around the year 2000. With homing abilities now discovered in these problematic pests, Southern Florida is likely not going to be rid of this problem anytime soon.
In the regions where these snakes have taken a strong presence – Everglades National Park and Big Cypress National Preserve – they have invaded the food chain, suffocating and eating animals of all sizes – even deer and alligators. Their invasive behavior has reduced the native populations of many wildlife creatures, including raccoons, bobcats and rabbits.
"This is way more sophisticated behavior than we've been attributing to them," said co-author Frank Mazzotti, a UF/IFAS wildlife ecology and conservation professor based at the Fort Lauderdale Research and Education Center, as cited by Discovery News. "It's one of those things where nature makes us go 'wow.' That is truly the significance of this."
For the study, the researchers captured and tagged 12 Burmese pythons and surgically implanted radio transmitters to allow them to track the movements of the snakes. As a control group, six of the snakes were returned to their capture point and let loose. The others were transported to drop points between 13 and 22 miles away. No matter the distance, the moved snakes were able to orient themselves and begin slithering their way home, maintaining their bearings for the entire trip, even in the case that some took nearly 10 months to return home.
The discovery that Burmese pythons have this amazing inherent GPS, is very concerning to the South Florida ecosystem, according to Mazzotti. While it is of great concern that these predators can easily strangle large animals to death, it is of more concern that people are also in danger from these often monster snakes.
While human attacks are rare, they have been known to injure and kill people, especially toddlers. In fact, there has been some reports that Burmese pythons have crushed and swallowed infants, Jennifer Viegas of Discovery News explained.
It is unlikely that these snakes can be totally removed from South Florida now that they have a strong foothold. However, the federal government in 2012 banned the import and interstate trade of the Burmese python, as well as the yellow anaconda and the North and South African python, which should help keep more snakes from being dumped in the Everglades by pet owners.
Still, the study authors emphasized that their findings have implications for management and conservation of the species.
“Animals that are adept at navigating and homing are better able to exploit resources that are relatively far away, widely spaced or seasonally variable. These abilities also reduce risks associated with searching potentially hostile or unfamiliar areas because the dispersing snakes can always return to a safe location,” according to the authors.
"Understanding navigation in invasive species improves the ability to control populations and limit dispersion," said Hart. "For example, the fine-tuned navigational capacity that the pythons exhibited may lower their risk when they move to and explore new areas."
“This research is useful for resource managers because it has implications for python movement behavior at the edges of the invasion front where there is a need for containment,” Pittman said.
"Invasive exotic reptiles continue to challenge agencies charged with protecting the health of south Florida ecosystems," said Everglades National Park Superintendent Dan Kimball.
The Burmese python has established itself as an apex predator in the Everglades. Some snakes have been removed from the region weighing in at more than 150 pounds and in excess of 18 feet in length.
What was once ruled mostly by alligators, the Burmese python is likely the new king of the jungle in South Florida.