Nature holds many surprises. Take the red backed salamander (Plethodon cinereus) for instance. In its chosen environment, damp, cool woods throughout Eastern North America, it is so abundant that if you were to weigh all of the deer and then weigh all of these salamanders in the same area the salamanders would outweigh the deer! Yet very few people ever see one of these amphibians.
When you think of amphibians, frogs and toads come immediately to mind. These are the ones we typically encounter in ponds, along rivers and in the case of toads our gardens. Our North American frogs serve as the stereotypical image of what an amphibian is. They go through a life cycle that begins with eggs laid in water, hatch out as gill-breathing tadpoles then change into air breathing adults who spend their adult lives living in or near water. This is not really an accurate picture of course because even among the world's frog species there are huge variations on this basic pattern.
The other group of amphibians that comes to mind is the salamander-newt family. Many assume, based on their knowledge of frogs, that this family lives a similar life-style. Some do, but the red-backed salamander certainly has some more surprises for us.
It is a hardy woodland salamander. So hardy in fact that it is active on warm winter days when other amphibians are hibernating. This salamander unlike most other amphibians migrates to communal burrows several centimeters below the surface. When it emerges it returns to its home territory of about 0.2 to 0.3 meters squared. That translates into up to four salamanders for every 4 square meters of forest floor. They live under rocks, fallen trees and prey on insects, worms and other invertebrates living in the leaf litter. They capture by using their sticky tongues.
They do not mate in water and in fact avoid it where they can. They mate on land in the spring and in the fall. The mail deposits his spermatophore near the female. This small packet contains his sperm but it is not deposited in her. She either rejects it or chooses it based on the vigour of his mating dance. Even then fertilization may be delayed for several weeks or months. Eggs are laid in clusters of 3 to 13 in moist, rotting cavities. The female defends them and turns them regularly.
There is no gill stage in this species of amphibian and a few weeks after hatching the young resemble small adults. Until they set off on their own their mother continues to guard them. She will mate every two years.
It will be two years before the young are sexually mature.
In these days of global warming, the other surprising thing is that here in Eastern Canada there are any of these salamanders at all. During the last ice age the nearest suitable habitat for these animals was at least several hundred kilometers to the south. These small 13 centimeter amphibians have had to slowly migrate north to claim renew habitats. No small feat considering the ice age melting left behind the Great Lakes as a barrier.
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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