No truly dangerous “poisonous” frogs native to Michigan pose a significant threat to humans through casual contact. While some amphibians in the state produce defensive skin secretions, these are typically not lethal to humans. Understanding amphibian toxicity helps clarify common misconceptions and provides guidance for safe wildlife interactions.
Understanding Amphibian Toxicity
The terms “poisonous” and “venomous” describe different ways toxins are delivered. A poisonous animal releases toxins when touched or ingested, meaning you get sick if you bite or otherwise consume it. In contrast, a venomous animal injects toxins, typically through a bite or sting.
Many toads and some frogs produce defensive skin secretions, primarily as a deterrent against predators. These secretions, such as bufotoxins found in toads, are generally irritants or mildly toxic if ingested. They can cause irritation if they come into contact with eyes or mucous membranes, but are not lethal to humans from casual handling. For toxins to cause serious issues in humans, they usually need to be swallowed or consumed.
Michigan’s Native Frogs and Toads
Michigan is home to numerous native frog and toad species. While some produce defensive compounds, none are considered highly dangerous to humans. Among the amphibians found in Michigan are the American Toad, Fowler’s Toad, Green Frog, Spring Peeper, Gray Treefrog, and Northern Leopard Frog. Most of these species are not considered poisonous to humans.
The Eastern American Toad and Fowler’s Toad, both native to Michigan, possess glands behind their heads that secrete a chemical called bufotoxin. This milky white substance acts as a defense mechanism against animals that might try to eat them. If ingested by small pets, bufotoxin can cause serious cardiac, neurological, and gastrointestinal problems, but for humans, it primarily causes irritation to the eyes or nose if contact is made. The Pickerel Frog also produces toxic skin secretions that can be irritating to humans if handled and are harmful to small animals. Northern Leopard Frogs, however, are not poisonous.
Safe Interactions with Wildlife
When encountering amphibians in the wild, it is advisable to observe them without handling them unnecessarily. If you do handle a frog or toad, wash your hands thoroughly with soap and water immediately afterward. This practice is important because amphibians, even when appearing healthy, can carry bacteria like Salmonella on their skin or in their environments. Symptoms of salmonellosis, such as stomach cramps, diarrhea, and fever, usually appear 12 to 72 hours after exposure and can be severe, especially for young children or individuals with weakened immune systems.
Avoid touching your eyes or mouth before washing your hands after any contact with amphibians or their habitats. Keeping amphibians out of areas where food is prepared or consumed is also a good practice to prevent potential contamination. By exercising caution and practicing good hygiene, individuals can safely coexist with Michigan’s native amphibian populations.