The American Bullfrog, both predator and prey
This month I am taking a short break from working on the Piping Plover feature documentary and am developing a film about the ecology of New England ponds. Frogs, in all their myriad incarnations, are keystone species, playing starring roles as both predator and prey.
American Bullfrogs are by far the most commonly seen. While filming and adventuring around local ponds with Charlotte we witnessed a dramatic scene where a Garter Snake snatched a Bullfrog from the road. As the snake was keeping his eyes on us, he was successfully dragging the frog into the cover of grass, simultaneously trying to devour the frog whole in one swallow. As you can see, the frog was enormous, compared to the mouth of the snake nonetheless, the snake was determined. We couldn’t continue to wait to see what took place but were convinced the snake was going to prevail and eventually swallow the frog.
Known predators of American Bullfrogs include Great Blue Herons, Great Egrets, Little Blue Herons, snakes, raccoons, Belted Kingfishers, and turtles.
Little Blue Heron eating a froglet
As tadpoles, American Bullfrogs are herbivores that eat aquatic plants. As adults, ABullfrogs are carnivorous ambush predators who eat insects, birds, fish, snakes, baby turtles, bats, rodents; anything that fit into their wide mouths. They even eat each other! Bullfrogs wait patiently for prey to pass by and and then use their powerful back legs to pounce. American Bullfrogs are North America’s largest. Females are generally larger than males and can grow up to 8 inches.
Note the tail on the above Bullfrog froglet. Half tadpole, half frog, froglets are outgrowing their tadpole stage, but are not yet fully fledged frogs.
An easy way to tell the difference between an American Bullfrog and a Green Frog is to look at the fold of skin behind the eyes. The ABfrog’s wraps around the very large eardrum (tympanic membrane). The Green Frog’s fold on either side runs along the length of the body.