“Jug-of-Rum” Choir of Summer
The Great Outdoors | July 16, 2020
By Jackie Scharfenberg, Forest Naturalist, Wisconsin Department of Natural Resources
“Jug-o-rum, jug-o-rum, rum, rum!” Sing it low, sing it loud! “Jug-o-rum, jug-o-rum, rum, rum!”
Oh, excuse me! You caught me practicing for the summer pond concert. We, male American bullfrogs (Lithobates catesbeianus), sing bass while the green frogs twang tenor, and the mosquitoes buzz high soprano. You can catch our concerts from late May, after the water warms, into July. We sing songs of territorial defense with periodic wrestling matches and love songs to woe the ladies. “Jug-o-rum!” Our preferred concert venues include quiet lakes, large ponds, slow rivers and open wetlands; all with permanent calm water and tall, undisturbed shoreline plants.
It’s easy to pick us out in the choir, since we’re the largest frogs. We average 3.5-6 inches in length and weigh
1.1 pounds. We can reach sizes of up to eight inches and 1.5 pounds. Our females grow larger than the males. We sport olive/brownish color backs with darker spots, especially on our legs. Our bellies appear white with gray or yellow spots. If you look closely, you can spy our green upper lips, webbed back feet, and a tympanic fold that wraps around our ear or tympanum. You can also tell the males from the females by the size of their tympanums. Male tympanums measure about two times larger than their eyes while our females are the same size as their eyes, or slightly smaller. In breeding season, our males’ throats turn a bright yellow.
After attending a mating concert, females breed with the males and then each lay up to 20,000 eggs in a large film. These films can cover areas from 5.4 to 10.8 square feet (about card table size) that float among the plants in quiet protected locations. After about four days, the spotted tadpoles emerge and begin grazing on aquatic plants, bacteria, protozoans, pollen grains, and other small particles. Our tadpoles remain in the water for two or three years; reaching almost seven inches in length. That’s why we reside in places of permanent water.
We hunt with an ambush, “sit-and-wait” style. When prey comes by, we lunge with our powerful back legs and mouths wide open. Did you know we can jump up to ten times our body length? That would be like you jumping more than the length of a school bus! With a flash our mucous-coated sticky tongues capture our prey. While holding the prey with our powerful jaws, we swallow it down. We eat just about anything we can fit into our wide mouths; from worms and insects to snakes, frogs (including other bullfrogs), tadpoles, mice, and aquatic eggs. If we avoid being eaten by herons, egrets, turtles, water snakes, raccoons, and people (who enjoy frog legs), we can survive to the ripe old age of seven
to nine years.
With the cold water of fall, we bury ourselves in the mud constructing small cave-like structures. The following spring, we’ll re-emerge and start up the choir again!
We hope you can catch one of our summer concerts. Remember, slow and low – “jug-o-rum!”