Invasive Frogs Threaten Arizona Snake Survival

Since 1926, invasive bullfrogs introduced for sport and food have become a major threat to Arizona's native northern Mexican garter snake. This snake now occupies only about 10% of its original territory, largely due to the proliferation of bullfrogs and other nonnative species. These bullfrogs impact the native snakes by preying on them directly and by competing for or consuming their natural food sources, such as leopard frogs and fish.

Evidence of this threat is clear, with field observations in areas shared by both species showing a scarcity of young snakes. Researchers have documented tail injuries on a high percentage of adult northern Mexican garter snakes, indicating frequent predatory attacks. Slow reproduction rates further complicate recovery efforts for the native snake population.

Conservation initiatives are underway to combat this invasive species. In places like Scotia Canyon, efforts focus on controlling bullfrogs and reintroducing native prey. These projects, part of a larger bullfrog control program in southern Arizona, involve various methods like netting tadpoles and shooting adult frogs. Such efforts aim to reclaim wetlands and support the recovery of native amphibians and reptiles.

These control programs have shown positive results, with native species like the Chiricahua leopard frog returning to areas where bullfrogs have been managed. However, consistent funding is crucial for ongoing surveillance and control to prevent reinvasion. While effective in smaller water bodies, extending these methods to larger river systems presents a significant ongoing challenge in Arizona's conservation efforts.