Wilderness Underfoot: Bullfrogs

StoryImage( ‘/Images/Story//Auto-img-115031750518000.jpg’, ”, ”);
StoryImage( ‘/Images/Story//Auto-img-11503175288558.jpg’, ”, ‘The bullfrog – Rana catesbeiana is the largest North American frog. It can grow to 8 inches in length, or a total of 18 inches if you include the hind legs. Bullfrogs are powerful jumpers. This frog is native to the eastern half of the continent.’);

The largest North American frog has a big voice and a hefty appetite to match its size

Since early last fall, these behemoths of the amphibian world have stayed out of sight, hibernating and patiently waiting for balmy temperatures to draw them out. Over May and June, as ponds, lakes and streams heat up, the bullfrogs gradually become more active.

From now until midsummer, you’ll hear the characteristic call of the bullfrog—jug-o-rum jug-o-rum—booming out over just about any permanent, well-vegetated body of water. The call can travel distances of a mile or more.

This is the noisiest time of year for bullfrogs as the males stake out territory, shout at one another, and fight over turf by kicking, biting and bumping. It is the beginning of bullfrog breeding season. Early in July, the female will lay tens of thousands of eggs in a blob of jelly that floats on the water surface. About four or five days later, tiny tadpoles will emerge from the eggs and begin a long “childhood” that may last up to three years.

Tadpoles start life with a diet of algae and all sorts of organic muck they find in the water. As they grow, they add insects, fish, crustaceans and other amphibians to their diets. In their last few months as tadpoles, their legs will emerge, their tails will be absorbed into their bodies, and they’ll lose their gills.

Adult bullfrogs will try to eat any animal they can get into their mouths—and occasionally some creatures they can’t get into their mouths. They’ll hungrily gorge on fish, other amphibians, snakes, turtles, small mammals and birds. Bullfrogs will eat their own kind just as readily as they eat other animals. They’ll even eat scorpions and other stinging animals, undaunted by repeated stings as they gulp down their prey!

As with other giants in the natural world, where large animals tend to have longer lives, bullfrogs are exceptionally long-lived compared with other amphibians. Wild bullfrogs may live six to nine years, and the record for one in captivity is 16 years.

So long as they have a permanent water body in which to live, bullfrogs can endure heat better than other amphibians, and they’ve actually benefited from global warming—sometimes to the disadvantage of other species. In parts of the West, where they’ve been introduced, bullfrogs have become a destructive invasive species. They eat young fish and amphibians, endangering other species and destroying the balance of sensitive habitats.

From the June 14-20, 2006, issue

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