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Invasive Pythons Can Find Home 20 Miles Away, Study Says

For Burmese pythons, there’s no place like home—and now a new study shows the snakes can navigate from over 20 miles (36 kilometers) away to get there.

At up to 18.8 feet (5.7 meters) long, Burmese pythons are among the world’s largest snakes, and they have become notorious in the past decade as one of South Florida’s worst invasive pests. (Related: “Longest Burmese Python Found in Florida.”)

Burmese python. Photograph by Eureka/Alamy
Burmese pythons have surprising navigation skills. Photograph by Eureka/Alamy

The alien reptiles—which likely are descended from animals that escaped captivity—have been eating many of the native animals. In the Everglades, some of the python’s native prey are at risk of going locally extinct. (Related: Pythons Eating Through Everglades Mammals at ‘Astonishing’ Rate?”)

Figuring out how Burmese pythons navigate might help scientists learn how to stop their spread, so reptile and amphibian expert Shannon Pittman wanted to find out if navigational abilities found in other snakes also exist in Burmese pythons.

“Most snakes have a home range and like to stay in that area. When they are moved to a new location, they tend to wander and try to figure out where they are,” said Pittman, who recently received her Ph.D. from the University of Missouri and is now a postdoctoral fellow at Davidson College in North Carolina.

Finding Their Way Home

To determine how well the pythons could navigate, Pittman and colleagues moved the snakes out of their home range in the Everglades and tracked how the reptiles moved. (See Everglades pictures.)

Although scientists can readily track species like wolves and birds with GPS trackers attached to the body, snakes don’t have a convenient neck or leg on which to secure the unit.

That meant each of the 12 snakes Pittman collected had to be anesthetized and get a small radio tracker implanted in its body.

As Pittman and colleagues followed the snakes over time, she was surprised to learn that the snakes were able to reliably head in the direction of their home ranges where they were captured, according to results published March 18 in Biology Letters.

Pittman isn’t sure how the Burmese pythons can home, but she believes that celestial cues are a possibility, since other snakes are known to navigate by the stars. (Also see “Dung Beetles Navigate Via the Milky Way, First Known in Animal Kingdom.”)

Overall, Pittman said that the results are important for scientists working to control the snakes.

“Biologists need to know how fast the snakes might spread and what corridors they are likely to use,” Pittman said, “so that conservationists can prevent population expansion.”

Follow Carrie Arnold on Twitter and Google+.

Read Homing Pythons Re-Enact Homeward Bound on our Phenomena blog.

Comments

  1. Tony Cooley
    United States
    March 24, 12:56 am

    My first comment apparently didn’t post, so I will repeat the basics of it. These snakes were transported in closed containers so they do not have a travel pathway to indicate where home is. They would thus not know which direction home is unless either: 1) they had already traveled beyond the home range previously, say when young looking for an empty home niche, during mating travel, or due to shifting of home boundaries with time so they already had a mental map, or 2) they had a way to identify their home from a distance.

    If the second option is true, the celestial navigation option is insufficient as it could only provide latitudinal information, not longitudinal info. This is why mariners were limited in their navigation until a reliable chronometer was invented. This also applies to solar-based (including polarized light) mechanisms. Even if these mechanisms were useful, the snake would have to resolve differences small enough to identify a 20 mile movement.

    Magnetic fields, including declination and dip, are another option and apparently are a factor for carrier pigeons. Carrier pigeons are also transported to a distant location before being released to find their way home. This would have to be combined with information from the sun that incorporates time of day so the animal could tell how the observed horizontal component of magnetic field deviates from north. Simply perceiving the magnetic field alone without relating it to true north would only provide the dip information, which would be a roughly latitudinal-like circle around the globe. It would not actually follow the latitude, so perhaps the combination of magnetic, latitude, and direction to true north could allow definition of a position on earth.

    Another option is for the snake would be to move to its home latitude and then turn along that until it reaches home. This is what mariners did until the marine chronometer was invented. That has a risk of turning the wrong way and going away from the home range. The observed pathways of the 5 out of 6 snakes that made it within 5 km of their home could be examined with this alternative in mind.

    The last possibility would be some distinctive odor that could be detected at large distances. Something like a combination of pheromones that can be detected at very low concentrations and would be unique to a particular snake. This might be combined with the other mechanisms to form a composite mechanism. The snake might move toward the latitude of its home territory, or even closer using magnetic field information, and then when it is closer by following these mechanisms, detect the correct odor and even familiar landmarks to then correct its course to go directly home from that point.

    Before I would reject the first possibility, that the snake had previously wandered over the area where it was released and thus remembered the path to its current home, I would need to see both a replicate in which the snakes were moved again to a position farther away and east or west of their home, and also a study using young snakes (over several years) to see how widely they travel in seeking new territories, how much they travel to mate, and how stable their territories are with time.

  2. Tony Cooley
    United States
    March 23, 2:37 pm

    Offsetting a python 20 miles from its home range would not cause enough change in the apparent star positions for a snake to determine the direction back to its home from star position alone. Unless the snake knew the direction to its home, which it shouldn’t when it is moved by truck, navigating by the stars would be useless. A different answer needs to be sought.

    Perhaps there are odor combinations associated with its specific home range that it can detect from 20 miles away. That seems far fetched, but less so than celestial navigation when the snake would not know which direction it was shifted. It could be the snake’s own combination of odors it is seeking, which would mark its home area. Pheromones are detectable at very low concentrations. Perhaps it is something like that.

  3. Rajkumar Oberoi
    Delhi - India
    March 23, 9:12 am

    A vibrant species the problem is not to control population but find a suitable habitat to rehabilitate in snake paradise free from poachers.

  4. Vimal deve
    Muscat
    March 23, 6:38 am

    I like it all animal…

  5. Sk tyagi
    New Delhi
    March 23, 3:51 am

    No reliable information on reptiles tracking their homes may not be true & difficult to prove ok

  6. Sk tyagi
    New Delhi --India
    March 23, 3:48 am

    Well reptiles never fond of homes they take shelter in any holes cracks of stone soil or rock ?
    Well reliable findings of reptiles power to track homes as far as 36 km may not have scientific data ?

  7. Fin
    Jacksonville, FL
    March 23, 12:28 am

    how long can you call a species invasive?

  8. yakeria
    March 20, 12:16 pm

    do you sell snakes

  9. Ima Ryma
    March 19, 5:31 pm

    A Burmese python, I got born
    In the Florida Everglades,
    Where native critters are forlorn,
    Ending up as digested preyeds.
    And so some meddling humans stuck
    A GPS inside of me,
    Took me twenty miles off by truck,
    And let me go. How would I be?
    Well, the stars I be checking out,
    To do my navigation roam,
    Giving those humans little doubt
    That I knew how to get back home.

    Where I was born, I plan to stay,
    Cuz where there’s my will, there’s my way.