A few warmer days have brought snakes out of their winter dormancy. Reptiles are ectotherms, or cold blooded – active during the warm months but going into a state of physiological dormancy, called brumation, during the winter. Brumation is not the same as the hibernation exhibited by some warm-blooded animals (endotherms).
I recently saw a western terrestrial garter snake (Thamnophis elegans) on the levee at Big Lake (Shasta County CA). The snake froze as I approached. It never moved as I walked around it taking photographs, often less than a foot from its head. I began to consider the ways in which this garter snake, which was about three feet long, defends and protects itself.
Obviously the first line of defense is hiding, running away or keeping very quiet. This snake chose to remain immobile. If it were in the grass or were at least semi-hidden in some other manner, the tactic would most likely have been effective against me. Out in the middle of the levee , definitely less effective. Yet if I had been a hawk or other animal that used motion to detect its prey, remaining still may have proven to be an effective strategy. Occasionally a garter snake will also flatten itself when threatened. Perhaps that makes the snake appear larger than it actually is. If water is nearby, a garter snake might also go into the water for protection. If attacked or captured a garter snake will often writhe, coil and violently strike at the attacker in an effort to escape.
Garter snakes have musk glands that produce a pungent, foul smelling substance. A garter snake will release the contents of its musk glands as well as the contents of its cloaca (a common chamber that contains wastes from the digestive tract, excretions from the kidneys and reproductive products) and smear this pungent mixture on themselves and their attackers. As if this is not enough to discourage the predator, garter snakes can also regurgitate the contents of its stomach onto itself and its attacker. Quite an interesting array of deterrents!
Garter snakes also bite and inject a poisonous venom. This venom is present in very dilute concentrations, certainly not enough to harm a human beyond perhaps a very localized reaction from the poison itself or infection from a tooth breaking off in the wound. Garter snakes commonly use their venom to aid in the capture of small prey (where the venom could have an effect), not as a defense mechanism. However, when captured garter snakes will bite in an attempt to rescue themselves.
Rattlesnakes, coral snakes, copperheads and other “poisonous” snakes are well known for their obvious defenses, yet even the “harmless” garter snake has a ready arsenal of methods to protect itself.