London, March 5 : Researchers at Miami University in Ohio have discovered that arboreal snakes are more likely to fall from their trees in cold conditions.
University biologist Gary Gerald and his colleagues recorded the velocities, body postures, and balancing abilities of corn snakes (Elaphe guttata) on horizontal beams at 10, 20, or 30 degree Celsius in a climate-controlled laboratory.
The snakes were exposed to temperature for two hours before being induced to cross the branches that had diameters of three, six and ten centimetres.
Spotters were placed below to catch the snakes in case they fell, and a safety cushion was placed beneath the artificial tree so that the reptiles would not be injured on being missed by the spotters.
Reporting their findings in the Journal of Experimental Zoology, the researchers said that the snakes moved faster and were more stretched out along branches of all diameters when temperatures were high.
In contrast, at lower temperatures, the snakes moved much slower and adopted a looped posture to improve their stability, i.e. their bodies meandered along the branch.
The researchers said that the likelihood of the snakes' tumbling out of the tree was ten times higher at the coldest temperature than at the warmest temperature, even though they were still mobile.
According to them, the falling and the looped posture of the snakes indicated that temperature might be having an impact on their balance and movement.
The researchers have also revealed that snakes were not co-operating in colder climates, and would refrain from trying to cross the branches. In such cases, the researchers had to tickle the back of the snakes' tails to prod them along.
They observed that snakes in colder temperatures tended to fall from thin branches less often than from thick ones, perhaps because they could make more loops along the narrower surface.
They suggested that snakes' agility on thin branches provides them with an advantage over other tree-dwelling animals.
"People often think of snakes as being at a disadvantage by not having legs, but in trees there is really no question that they have a leg up," Nature magazine quoted Gerald as saying.
The researchers believe that the findings of this study may help explain some aspects of reptile ecology.
"That so many of the snakes fell when cold may help to explain why there are so few arboreal snake species outside the tropics," says biologist and flying snake expert John Socha at the University of Chicago in Illinois.