Sunday, October 3, 2010

Red-sided Garter Snake

The Red-sided Garter Snake is a race of the Common Garter Snake.  The Red-sided is found in western Minnesota and is replaced by Common Garter Snakes in the east.  Range maps in Reptiles and Amphibians of Minnesota by Breckenridge (1944) shows overlap between the two races in southeastern Minnesota.  My brother and I encountered this individual on the Cannon River Bicycle Trail in Goodhue County about 4 miles east of Cannon Falls.
Our Red-sided Garter Snake aggressively stood its ground, striking at us as we approached.  Recently garter snakes have proven to contain neuraltoxins, although in non-lethal quantities to affect humans.  The snakes also lack an effective method of venom transmission.  Although garter snakes are known to coil and strike, our snake may have been run over by a bicycle, which might explain its unwillingness to flee.

Wikipedia also reports that male and female garter snakes produce distinctive pheromones that allow males to find emerging females in the spring. Swarms of up to 25 males mate with each female.  Some males, however, practice kleptothermy.  Kleptothermy is when you steal someone's heat.  In this case, these males release female pheromones, attracting other males to attempt to copulate with them.  This action warms up the female-pheromone-releasing males, and makes them more active.  Studies demonstrate that these "she-males" are more active than cooler males and are thus able to mate more often.  Females are able to store sperm for several years.  The fertilized eggs hatch inside the female. Three to 80 young are then born live in a single litter, a condition termed ovoviviparity.

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