Female Impersonators

Pheromones cause the male snakes to chin rub other male snakes Pheromones cause the male snakes to chin rub other male snakesPhoto Courtesy of Paul Hancock In 1989, Dr. Mason was recognized as the first person to find a pheromone in a reptile. After he did this, clues to many of the other puzzle pieces surrounding the behavior of these snakes were revealed.  For example, one of the strangest behaviors that these snakes exhibited was seen in male snakes that had just exited the den. People would observe male snakes behaving like the females, which would cause all of the surrounding males to create a mating ball around the “she-male.” No one knew why the snakes would do this, or why the other males would think that the she-male was a female. After the discovery of pheromones, it was learned that these snakes were releasing the same sex-attractiveness pheromone that other males used to identify a female snake in mating balls. What benefit would a male receive from pretending to be female? Were they trying to distract the other males from the real female? Dr. Mason and Rick Shine, a biologist from theUniversity of Sydney Australia, think they know the answer.

The mating ball can help protect the male snakes from dangerous predators The mating ball can help protect the male snakes from dangerous predatorsPhoto Courtesy of Manitoba Wildlife and Ecosystem Protection Branch When the snakes “wake up” from their brumation period and exit the den, their body temperature is very low. Cold body temperatures make the snake slower and more defenseless against predators. Because garter snakes do not have fangs or any other way to defend themselves, the ability to move quickly from predators is the only thing that keeps them from becoming dinner. When the snakes emerge, crows and other bird predators are often waiting to take advantage of the slower, unprotected snakes and will quickly snatch them up. Mason and Shine believe that by imitating the females, the she-males are protecting themselves in two ways. The first is the natural protection provided from the mating ball; it would be very difficult for a bird to get the snake in the middle of the group. The second advantage to pretending to be female is the warming effect that is provided by the mating ball.  Naturally, warmer snakes are able to move faster. In a temperature test with live females that started at four degrees Celsius, those that were courted in a mating ball warmed to 20 degrees Celsius faster than those that did not have any suitors. Another study was conducted with actual she-males that were attracting male attention after leaving the den.  The she-males that researchers warmed up to at least 28 degrees stopped exhibiting female behavior after three hours, but those still at 10 degrees were still receiving male attention after five hours.