Finding a new species of wildlife is often a daunting task. Think the Amazon rainforest, Africa’s Mountains of the Moon, the depths of the ocean…but downtown New York City? Really?
A new species of Leopard Frog was discovered there recently and was confirmed last year as Rana kauffeldi. To you and I it looks like the common every day leopard frog (Rana pipiens) that can be found from Mexico to Southern Canada. It differs in its call and in its colouration. Depending on who you believe and when your source material was written there are between 8 and 14 species of Leopard Frogs in North America. Since the advent of DNA testing opened the door to a more refined method of sorting out species from sub-species a revolution has been sweeping taxonomic lists. New species are being identified while other species are being combined into a single species. The whooping swan (Asia) and the whistling swan (North America) are now one global species: the Tundra swan. African elephants are now two species: the African bush elephant and the African forest elephant.
Does it matter? Well yes it does when it comes to understanding genetic diversity and the health of the genera and to preserving unique species it does. But, to you and I? Well, no. Not so much.
Still as frogs go the Leopard frog is a pretty impressive one. The female can lay up to 7,000 eggs (although about 3500 is more typical) in a quiet wetland with submerged vegetation. The tadpoles hatch in one to three weeks and face a gauntlet of predators from snakes, turtles, herons, raccoons, mink, weasels, skunks and other frogs. It takes them two years to mature and that is about half their life expectancy.
Adults do not fare much better than tadpoles. Great blue herons, snakes, bull frogs, mink and racoons continue to find them tasty. Life is hard if you are a leopard frog. Around cities, cars take their toll to but so do chemicals released into the atmosphere. When they are carried into the ponds and marshes they alter the PH of the water and this can lead to bacterial infections. It is also a popular bait animal.
Despite all of this it is judged to being doing pretty well in most populations. However declines in amphibian populations worldwide have been documented and no species is considered completely safe. The reasons for these declines are generally blamed on factors related to habitat loss and climate change.
This frog is not the most northern species of amphibian. That honour goes to the America toad whose range reaches almost up to the tundra. The leopard frog can survive very cold temperatures and that in itself is somewhat of an achievement though not unique to this species. Leopard frogs enter hibernation in October and emerge in April when the temperatures have warmed up. They must leave some skin exposed to open water. They need flowing water to extract oxygen from, even when hibernating. They exchange gases through their skin. In order to survive winter they must select a body of water that does not freeze to the bottom.
The availability of suitable water ways does limit their locations but that does not mean you won’t find them in ponds that you know full well froze right to the bottom last winter. How did they get there if they could not have over wintered? They walked (hopped) from their wintering spots. This can be over a distance of 2 kilometers although most breeding ponds are closer than that from their winter homes.
Having bred, leopard frogs leave the ponds and wetlands to hunt in damp forests and meadows. Like all amphibians they need to keep moist but a good dew or rainfall can provide sufficient moisture for them.
At least that is our current understanding of this species but I have no doubt that will change as biologists continue to dig deeper into their lives.
Note: A version of this article first appeared in Bob Izumi's Real Fishing Magazine in
Dave's column At the Water's Edge. It is used with the permission of editor.
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