The ability to navigate our world is a skill that some people may take for granted. Imagine being abducted from your home, driven 15-20 miles away to a location you have never seen before, and being dumped on the side of the road. Do you think you would be able to find your way back without the use of a map or a GPS?
Well, researchers from the Biology Department at Davidson College have recently shown that Burmese pythons have such ability. Burmese pythons (Python molurus bivittatus) are one of the world’s largest snakes. They are native to southern Asia, but have recently become established in southern Florida. Thus, the snakes are invasive to this area of the world, with the ability to severely disrupt the native ecosystems in this region. Severe declines of several once-common mammal species in southern Florida appear to be the result of python predation. By studying the navigational capacity of this species, it may help us to improve the ability to control and prevent expansion of these snakes.
Burmese python (Python molurus bivittatus)
Navigational capacity allows an animal to determine when and where to move. Thus, the purpose of this study was to determine whether Burmese pythons have the navigational capacity to find their way home after being translocated miles away to an unfamiliar location. The ability to home after translocation involves both a map sense and a compass sense. A map sense allows for determination of position in relation to a goal, whereas a compass sense requires access to a reliable area to maintain orientation towards the goal. While many previously studied snakes have shown a lack of ability to home, the Burmese python is the first snake to demonstrate this skill.
The current study by Pittman et al. translocated six Burmese pythons 21-36 km from their original capture location and surgically implanted tracking devices into the snakes’ heads. The results of the study showed that five of the six translocated pythons returned to within 5 km of their capture location, while the other snake moved in the direction of the capture location. Since the pythons determined the bearing towards their capture locations and maintained those bearings, it shows that they have navigational map and compass senses. This is contrary to the predicted results that the pythons would exhibit random wandering movement similar to other snake species. Additionally, since the snakes maintained oriented movement over relatively long time scales, it shows that they maintained long-term movement goals and high motivation to reach home locations.
Map of the paths taken by the captured pythons
Potential environmental cues underlying the map sense in pythons include olfactory and magnetic cues, while the compass sense may involve magnetic, celestial, olfactory, or polarized light cues. However, further research must be done to determine the underlying sensory systems involved.
Understanding navigation in invading species such as the Burmese python improves our ability to control such populations and prevent expansion. This is important because such species have the ability to exploit resources that are widely spaced or seasonally varying, and disrupt food webs in invaded areas. Thus, understanding navigational capacity is critical in the context of range expansion by invasive species, and may prevent the decline of several prey animals.
References:
Pittman, S. E., Hart, K. M., Cherkiss, M. S., Snow, R. W., Fujisaki, I., Smith, B. J., … & Dorcas, M. E. (2014). Homing of invasive Burmese pythons in South Florida: evidence for map and compass senses in snakes. Biology letters, 10(3), 20140040.
