Jeff Green | Jul 23, 2009
Back to HomeOutdoors in the Land O'lakes - July 23, 2009 King of the Frogs – The Bullfrogby Lorraine Julien
I consider our family lucky to be living in a relatively clean environment where frogs still thrive. Although the peepers are a welcome sound in spring, it’s good to hear their high notes punctuated by the occasional deep voice of a bullfrog. Perhaps it is the wet weather we’ve had lately, but whatever – the bullfrogs are still tuning up, especially on warm rainy evenings! There’s a shallow little bay in front of our home where a resident bullfrog reigns supreme. Some say the call sounds like “jug-o-rum” but I think the sound is similar to a single note played on a tuba. The call can be heard over a distance of one kilometer.
This largest Ontario frog has a huge appetite (that matches its size!) and will eat almost anything it can stuff in its mouth, sometimes even using its front legs to push the food in! It can grow on average to about 6” (12-14 cm) long (sometimes more) but its long legs add another 7-10” (17-25 cm). Most are green or yellowish green. Luckily for us its favourite food is insects. Amazingly, this big fellow can occasionally devour a bat or a bird that happens to fly too close to the water.
Bullfrogs are never far from water and are seldom seen on land. Its preferred habitat is a quiet cove on a lake with lots of lily pads and vegetation. During cold weather, they dig into the muddy sediment of a lake or river bottom. Once spring arrives and the water temperature rises, the bullfrog emerges from hibernation and soon gets in the mood for mating. In fact, its deep croaking call lets other males know they shouldn’t intrude on his territory. Bullfrog territories, of several metres across, are usually well established by June.
Girl frogs pick the best territory to lay their eggs, rather than the handsomest frog. When they’ve found a good site, they approach the proprietor who obligingly mates with them. Bullfrogs can have six or more females in their harem – if the territory is especially desirable. Eggs hatch into large tadpoles fairly quickly – in 3 to 5 days. Maximum lifespan can be up to ten years in the wild. Just in case you get a chance to see one of these giants up close, the male can be distinguished from the female by the large round eardrums on either side of its head.
Natural predators include minks, raccoons, skunks, great blue herons, water snakes, pike, bass and snapping turtles. Tadpoles are eaten by dragonfly nymphs, leeches, fish and giant water bugs.
Once unbelievably abundant, frog numbers have declined drastically, probably because of widespread pollution and the destruction of wetland habitats. According to some statistics, million of frogs are used annually for science or food in North America.
With human and natural predation, it’s easy to see how frog populations are in decline. The king bullfrog, in particular, is in real trouble in Ontario. Their big meaty legs have been a restaurant favourite for many years. In Frontenac, and many surrounding counties, as well as all provincial parks, it is illegal to catch them. In some areas of the province, up to 10 can be caught legally from late July to mid-October if you have a fishing license.
Global warming and a thinning ozone layer may also contribute to their decline. High acidity in many bodies of water kills eggs and tadpoles. Because they breathe through their skin, amphibians such as the frog easily absorb any toxic substances.
Although bullfrogs are native to North America, they’ve now been widely introduced around the world and, in fact, are now farmed commercially.
On the internet I was surprised to see that e-bay advertises bullfrogs at “fantastic” prices. I checked though, and it was mostly children’s clothing with bullfrog illustrations--not the real thing!
As Kermit would say, it’s definitely not easy being green!