Wednesday, August 12, 2009

Our Missy Bullfrog

by Donna L. Watkins

We built a small pond in our backyard for the purpose of attracting frogs. Since it's not very large, we've had mostly Green Frogs in residence with other toads and tree frogs using it for mating. But this year I took some photos and didn't know we had a Bullfrog until I looked at the photos on the computer.

Green Frogs and Bullfrogs look very similar. The way to tell them apart is by the dorsal ridges that go down the Green Frog's back. In Bullfrogs they are not present. Bullfrogs have a ridge that goes around the tympanum (the circle area behind the eye) instead of down the back. Compare the Bullfrog photo here with the Green Frog photo below.

© 2009 Donna L. Watkins - Bullfrog at Our Small Backyard Pond
Back in Alabama we had a bit larger pond and did attract a Bullfrog for a few years. They take dominance over a pond, so we didn't see much else those years.

The Bullfrog (Rana catesbeiana) is the largest Virginia native frog measuring from 3-1/3 inches to almost 8 inches long not including the legs which can be from 7-10 inches long. They are also the largest frog in North America. They are a drab brownish-green color on top with a yellowish white coloring below. The large circles behind the eyes are their eardrums with the females being about the size of the eye and males being considerably larger than the eye.

Territories are emphatically established with calls, postures, chasing, jumping and fighting if necessary. Their distinctive call is said to sound like a distant roar or bellow of a bull.

Bullfrogs will eat almost anything living that it can at least partially swallow. They are voracious predators, feeding on any small animal they can catch, including big and small insects, crayfish, other frogs and bullfrogs, fish, worms, turtles and even small snakes.
© 2005 Donna L. Watkins - Male Green Frog in Backyard Pond
There are records of Bullfrogs feeding on birds and baby alligators. They have teeth on the roof of their mouth and a tongue capable of flipping prey into their mouth. Bullfrogs can leap up to 6 feet in distance. They help to keep down mosquito populations but they can also have a negative effect on other species of frogs since they don't really have any natural predators.

They can secrete nasty toxic substances from their poison glands (called paratoid glands) that can poison a dog if it tries to eat one.

This frog species prefers larger bodies of water, but will take the territory of a small backyard pond. Warm, calm, shallow waters are their favorite places. They can be found at lakes, ponds, rivers, or bogs.

They breed from May to August in Virginia. During breeding season the throat of the male Bullfrog is yellow, and the female's is white. Male bullfrogs chorus at breeding ponds and females give aggressive calls responding to the breeding calls of the males. The females are attracted to males with territories that provide the most food.

Fertilization is external, with females depositing up to 20,000 eggs in quiet and protected water. The egg mass is a large floating mat with a foamy film up to a yard wide. Fertilization is then accomplished usually by one male.

Tadpoles emerge about four days after fertilization and tadpoles may remain in the tadpole stage for almost 3 years before transforming into frogs. The longer the better for the frog since they will be bigger and have a better chance of survival. Adults reach sexual maturity after 3 to 5 years and have been recorded to live up to 7 years.

I don't know if our Bullfrog will stay around since the "neighborhood" may not be suitable for the female Bullfrog, but it's nice to know that our backyard habitat brought one by even if it's just for a visit.

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Dakota House said...

I have a small backyard pond that is home to a beautiful big bullfrog that I love. Someone just gave me a turtle, and I am afraid to put him in with my bullfrog. Should I be? They are about the same size.

Thank you so much for any help,


P.S. I have pictures of my pond and frog on my blog:

sharingsunshine said...

This forum post may be helpful to you ... or you could post a question of your own.
Turtle Forum.

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