During the first warm weather in March, accompanied by heavy, or prolonged, rain and melting snow in the woodlands of Lancaster County, Pennsylvania, wood frogs and spotted salamanders rouse from hibernation under soil and carpets of dead, fallen leaves on forest floors and make their ways through the rain and over soggy, fallen leaves to shallow, fish-less depressions rapidly filling with water. These amphibians enter those pools of cold water of varying sizes to spawn.
By March, locally, skunk cabbage flower hoods and tussocks of green grass above last year's dead, light-brown blades are visible in inches-deep water of vernal pools in local woodlands. And many rims of those pools and tree trunks fallen into the water are green with moss, making these pools all the more lovely.
Vernal pools and ponds in woods from March into summer are amphibian havens in the mid-Atlantic States. Being animals "with two lives", Jefferson and spotted salamanders, which are mole salamanders, wood frogs, spring peeper frogs and upland chorus frogs live as youngsters in small, shallow, usually temporary, pools. And American toads, pickerel frogs and eastern newts, which is another kind of salamander, live part of their lives in permanent, but small, woodland ponds.
Jefferson, spotted, marbled and tiger salamanders are called mole salamanders because they burrow through the soft, damp soil, just under the forest floors' dead-leaf carpets, to catch and eat invertebrates. For that reason, these fat-bodied salamanders are seldom seen, except when spawning.
Wood frogs usually ingest invertebrates above the leaf litter, thus reducing competition with mole salamanders. But woodies scramble under the leaves when predators threaten.
Jefferson's salamanders and spotted salamanders are always silent, including when spawning. But male wood frogs utter choruses of hoarse croaks that entice female wood frogs into the pools to spawn. Those wood frog concerts in March can be heard from several yards away.
Each spotted salamander egg mass, one of several, is in a white, gelatin-like substance and lies on the bottom of the pool. Wood frog egg masses, are enveloped in clear gelatin and float on the surface of the water. Salamander larvae prey on invertebrates in their shallow pools, including fairy shrimp and midge larvae. Wood frog tadpoles feed on dead tree leaves fallen into the pools, and growing alga. Their different diets allow the young of these two species to live together in the same pools without competing with each other. And they must eat well because each year the young are pitted in a race to develop lungs and escape the shallow pool before it completely dries in summer.
Spring peepers and chorus frogs spawn in temporary woodland pools, but also in more permanent ponds in woods. These related tree frogs spawn by late March and through much of April. Although they are seldom seen because they are small and camouflaged, their primeval calls are pleasant to hear on spring evenings. They are voices in wooded wetlands, particularly in the dark.
Male peepers "peep" loudly, while male chorus frogs utter a short, gentle trill that sounds like somebody running a finger nail along the teeth of a comb. Both species call from grass stems on the edges of pools and ponds.
The long, musical trills of male American toads join the ancient concerts of peepers in permanent ponds by the second week in April. Those toads are visible sitting in the shallows of ponds as their throats bulge out with each trill. As with all frogs and toads, the toads' throats blowing out like a balloon amplifies the sounds of their courtship calls to bring the genders together for spawning.
I enjoy hearing the ancient concerts of male frogs and toads, anytime, day or night, at pond edges and in wetlands in the woods during April. The peeps of peepers, the trills of toads, the "snores" of pickerel frogs that date back millions of years transfer me to the long ago Age of Amphibians in my imagination.
Eastern newts spawn in permanent woodland ponds. Their larvae develop lungs and leave the water to hunt invertebrates for a few years on leafy forest floors at night and during rainy days. On those leafy floors they are called red efts because they are red. But at some point those efts re-enter woodland ponds to spend the rest of their lives in those watery habitats where they consume invertebrates and the eggs of other amphibians. Newts may have left the land for life in ponds where few salamanders live because they couldn't cope with the competition of other land salamanders. They found a new niche for themselves and developed poisonous skins to repel predatory fish.
Amphibians today are remnants of their former glory millions of years ago. Some species depend on vernal pools and ponds to carry out part of their life cycles. And we, today, can enjoy hearing their wild, ageless choruses.
No comments:
Post a Comment