Common Name: American Bullfrog.
Scientific Name: Rana Catesbeiana (Lithobates Catesbeianus).
What to look for? American Bullfrogs are typically green or gray-brown with brown spots. Their coloring tone can be a light or dark shade. They have easily identifiable circular eardrums, or tympanum, on either side of their heads. A bullfrog's head is broad and flat, with a large mouth. Underparts are white. The iris of the eye is either golden or reddish bronze. The hind feet are fully webbed. Also, during the breeding season the throat of the male American Bullfrog is yellow, whereas the female's is white.
Where can they be found at Carillon Stonegate Pond? Look near the shallow edges of Carillon Stonegate Pond. You’ll find American Bullfrogs sitting on the edge or around pond plants. You may see them completely above the surface of the pond. Or you may only see their eyes popping out of the water.
How big are they? The American Bullfrog averages approximately four to six inches in length. They weigh in at around 1 ½ pound.
What are their skills? Swimming! Jumping! The American Bullfrog is a powerful swimmer, with strong, long back legs and webbed feet. They can generally leap upward about 3 feet, but they are able to jump a distance of 6 feet easily.
How else do they behave? Male American Bullfrogs produce loud calls to attract females and establish their territories. They are quite aggressive when defending their territory. The American Bullfrog is a nocturnal predator that will ambush just about anything they can fit in their large mouths. They sit quietly and wait for prey to pass by, then lunge with their powerful hind legs, mouths open wide.
What’s for dinner? American Bullfrogs are carnivores. They like to eat crayfish, water beetles, snails and dragonfly larvae. The also eat fish, small turtles, and even other frogs! Bullfrogs have their own predators. Around Carillon Stonegate Pond, you may have seen Great Blue Heron and Great Egrets swallowing a frog. Other predators include turtles, water snakes, and raccoons. Most fish are averse to eating American Bullfrog tadpoles because of their undesirable taste.
Where do they take up residence? American Bullfrogs must live in water and are therefore usually found near lakes, ponds, rivers, or bogs. They prefer warm, still, shallow waters. They are among the most wide-ranging of all North American amphibians, residing from Canada, throughout the continental United States, and as far south as Mexico.
When and where do they breed and nest? Breeding season runs from late May into July. American Bullfrogs gather at breeding ponds in early summer, much later than most native frog species. Males will stake out territories with good egg-laying sites. They call out loudly to attract females. And they will defend their territories, chasing away rival males. After mating, females lay masses of up to 20,000 eggs in a film on the water’s surface. The bullfrog eggs will hatch in approximately four days. Tadpoles hatch out in July and remain in the ponds through that summer and the following winter. And, in the late summer of their second year, they complete their metamorphosis into frogs. Adults reach sexual maturity after 3 to 5 years.
Where do they migrate? We have all played the arcade game “Frogger” – frogs migrating would be just as unsuccessful! However, since North American bullfrogs prefer warm weather, they hibernate during the cold weather. The American Bullfrog may bury itself in mud and construct a small cave-like structure for the winter.
Do they make any interesting sounds? The American Bullfrog has a deep and resonant baritone call that resembles the “mooing” of a cow, hence its name. Only males emit this trademark "jug-o-rum" bellow. You can hear their choruses during the day or night around Carillon Stonegate Pond. They say that the call of a male bullfrog can be heard for over one mile. Here is a link to the sounds of the American Bullfrog.
Interesting Facts About American Bullfrogs:
Bullfrogs can leap as far as ten times their body length – approximately 6 feet.
The American Bullfrog is an introduced, rather than native, species in the western United States.
On the U.S. Department of Agriculture’s Invasive Species list for the western U.S., given great threat to native frogs due to the American Bullfrog's voracious feeding habits and the size and competitive ability of the larvae.
A group of frogs is called an “army”.
Their lifespan in the wild is estimated at 8 to 10 years.
For more information on the American Bullfrog and sources of information used in this blog (these are the sources that I am using to learn as I blog), please visit National Geographic, Nature Mapping Foundation and the University of Michigan’s Animal Diversity Web.
The Carillon at Stonegate community is very fortunate to have a variety of wetland, forest and prairie environments conducive to a variety of birds and other wildlife, insects and plants. Our community and the Kane County Forest Preserve do an exceptional job in maintaining this natural environment – both for the benefit of the birds and wildlife and for our residents to enjoy.
Take a hike and see what you can find – and identify!