Wednesday, June 24, 2009

It Ain't Easy Being Green

Last night I slept in my cabin that floats at the edge of a large swamp of several hundred acres on Lake Champlain. I try to stay there every few weeks or so in the summer, where, after kayaking from dusk into darkness, I sit, listen to a baseball game on the radio, and then listen to the sounds of the water and the swamp as I fall asleep.

Last night I heard the muskrats in the swamp, the occasional squawk of a great blue heron disturbed in its roost, the buzzing of mosquitoes at the screen door and the beavers splashing along the lake shore, all sounds I have heard many times before.

But apart from this, it was silent. That has never been the case before. In past years the swamp and the surrounding woodlands have been filled with the sound of frogs, from the spring peepers and wood frogs of the early spring, to the leopard frogs, pickerel frogs, green frogs, bullfrogs, gray tree frogs, western chorus frogs and even their cousins, the American toad (see for both pictures and sound samples). In fact, frogs have always been everywhere here, at least since I first moved to Vermont this week some seven years ago. During some summers it has been impossible to take a step without causing a frog, buried deep in the grass, to leap out of the way, and I leave the mower high to keep from acting as the inadvertent grim reaper of my neighbors. In the same town in which I live there is even a commercial frog collecting company that captures them for biology class, and locals have told me of earning extra money as kids by capturing big bags of frogs.

But this year, almost total silence. The peepers and tree frogs and wood frogs appeared and disappeared just as quickly, and I’ve hardly heard any of the others all. In past years, the waters of the swamp have nearly boiled with tadpoles as they approach maturity, but this year I have hardly seen any at all. And last night in the swamp, apart from a distant, single bull frog calling in vain all alone, nothing.

Amphibians are endangered nearly everywhere and as the journal BioScience tells me:

“Amphibians’ physiology (permeable skin) and complex water-and-land life cycle expose them to more environmental changes than most animals, and though they have survived climate changes before, today's changes are accelerating too rapidly for frogs to keep pace.
Also, frogs’ eggs have no shells, exposing embryos to increased UV-B radiation levels, which can cause harmful mutations. Pollution has contaminated the water frogs thrive in and global climate change is causing higher levels of infectious diseases.”

I am not a scientist and am not quite certain that the low level of frogs this year is due to the factors cited above. It could be some natural, cyclical fluctuation due to weather conditions or other factors. I do know that when the lake and the swamp froze this winter, for example, the water level was much lower than in recent years, and I wonder if the lack of sufficient ice cover caused an abnormally high die-off of hibernating frogs. Similarly, the lake never reached flood stage this spring and some habitats that usually are inundated remained dry. This, too, may have affected the population.

I do know that the silence makes nights in the cabin a bit longer, and more lonely. And that great blue heron may simply have been hungry.

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