Species Profile: American Bullfrog

Popular worldwide as a food source, pet, and for educational purposes (who hasn’t dissected one?), the American bullfrog has also become a formidable invasive pest.  

brrrrrp... I'm invading an aquatic ecosystem near you. (Photo credit: Wikimedia commons)

The American bullfrog (Lithobates catesbeianus or Rana catesbeianus, depending on who you talk to) has a lot to offer.  It’s a large charismatic amphibian that can be kept as a pet, dissected in a science classroom, or eaten as a great source of protein.  Unfortunately, the many uses of American bullfrogs also led to considerable export over the last 200 years.  Native in the eastern United States, American bullfrogs have become invasive in western US and have also been established intentionally and unintentionally in over 40 countries around the world.  Their progress has been described as nearly unstoppable, and models suggest that climate change may only serve to exacerbate their invasion in some areas.

Where they have been introduced, American bullfrogs have had dramatic impacts due to their voracious appetites, prolific reproduction, and adept dispersal.  Tadpoles gobble up algae and can outcompete other organisms for valuable resources.  As adults, bullfrogs will eat whatever they can fit into their mouths- insects, small amphibians, other bullfrogs, rodents, snakes, even birds.  In addition to limiting resources for other species, bullfrogs turn a lot of those calories around into reproduction- a female can produce 20,000 eggs in a single clutch, and an average of around 5,000 of those will actually hatch.  Finally, bullfrogs can transmit chytrid fungus, a disease that has been plaguing amphibian populations worldwide.

With such dramatic impacts, it’s no wonder that the American bullfrog has found its way onto the IUCN list of the world’s 100 worst invasive species.  Even the folks over at “Save the Frogs!” don’t like them!  As a result, there’s a lot of interest in bullfrog control.  We recently got our hands on some frog legs, and coming up we’ll share a few ideas on how invasivores can do their part to quell this invasion.

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