Garter snakes and rattlesnakes are common North American inhabitants, often sharing habitats. Rattlesnakes are known for their venomous bite and tail rattle, while garter snakes are smaller and non-venomous to humans. Their shared environments frequently raise questions about their interactions, especially predatory relationships.
The Surprising Reality: Garter Snakes and Rattlesnakes
Garter snakes do not typically prey on rattlesnakes. These species rarely prey on one another due to distinct dietary preferences. Garter snakes primarily consume amphibians like frogs and salamanders, earthworms, insects, and small fish. Rattlesnakes are ambush predators that mostly target rodents, birds, and other small mammals. Their distinct diets mean they do not directly compete for food.
Their interactions are characterized by peaceful coexistence. Both garter snakes and rattlesnakes can share communal denning sites, known as hibernacula, during colder months. This shared shelter helps them conserve energy and survive harsh conditions, highlighting a surprising level of tolerance. While a large rattlesnake might occasionally consume a small garter snake if food is scarce, it is uncommon.
Beyond Rattlesnake Venom: Garter Snake Resistance
Garter snakes possess a remarkable adaptation, but it is not immunity to rattlesnake venom. Certain garter snake populations, such as the common garter snake (Thamnophis sirtalis), have evolved significant resistance to tetrodotoxin (TTX). This potent neurotoxin is found in rough-skinned newts (Taricha granulosa), a prey item for these snakes. This resistance allows garter snakes to consume newts without succumbing to the toxin that would be lethal to most other predators.
The physiological basis for this resistance involves specific changes in their voltage-gated sodium channels in skeletal muscle and peripheral nervous system cells. These altered sodium channels prevent TTX from binding, disrupting nerve and muscle function, and neutralizing its paralytic effects. This adaptation results from a coevolutionary “arms race” where newts producing potent toxins drive the evolution of greater resistance in garter snakes, and vice versa. This specialized resistance to newt toxins does not extend to rattlesnake venom; a rattlesnake bite can still be fatal to a garter snake.
Ecological Dynamics and Coexistence
The relationship between garter snakes and rattlesnakes exemplifies the intricate ecological dynamics in natural environments. Their ability to coexist, even sharing dens, shows how different species can occupy distinct niches within the same ecosystem without direct conflict. Garter snakes control populations of amphibians and insects, contributing to the balance of their local food webs.
This peaceful cohabitation highlights how species adapt to their environments. The distinct diets and behaviors of garter snakes and rattlesnakes allow them to thrive in shared habitats, each fulfilling its own ecological role. This interaction demonstrates the diverse strategies organisms employ to survive.