Silent spring

March 26, 1997|By DON C. FORESTER

MID-MARCH FOUND ME sitting in an aging red Honda beside a wind-swept stretch of New Germany Road in east-central Garrett County. The sun had gone down and a cold rain had begun to fall -- the raindrops competing for air space with the large, wet flakes of a late winter snow. The driver's-side window was open, and the left side of my face ached as I strained to hear above the sound of the frigid, howling wind.

My attention was riveted on a shallow ditch, etched from the base of a steep rocky bank, and less than two feet from the asphalt surface of the roadway. This unlikely spot was the last known breeding site in Maryland for the mountain chorus frog, Pseudacris brachyphona.

As I listened in vain -- my ear mentally tuned to the frequency band of the male frogs' advertisement call -- prophetic words issued softly from the tape deck beneath the car's dash:

''Hello darkness, my old friend, I've come to talk with you again/ Because a vision softly creeping, left its seeds while I was sleeping,/ And the vision that was painted in my brain still remains --/ Within the sound of silence.''

In 1966, when Paul Simon penned the ''Sound of Silence,'' the mountain chorus frog was found throughout much of the Allegheny Plateau in Maryland. Today, hardly three decades later, its harsh trill no longer punctuates the nights of Maryland's montane wetlands.

Last spring, supported by a subsistence grant from Maryland Department of Natural Resources, I spent 12 weeks combing the remote back country of Allegany and Garrett counties, searching for mountain chorus frogs, arguably the most threatened of Maryland's 20 species of frogs and toads. During that period I logged more than 3,000 road miles and visited all historic breeding sites recorded in the data base of the Maryland Natural Heritage Program.

Suitable habitat was everywhere -- the frogs were not! In the end I located one population of 17 adults -- eight males and nine females. Over the course of the reproductive season the females collectively laid 978 eggs, most of which hatched. One male (appropriately nicknamed ''Lucky'' by my field assistants) mated with three of the females, further exacerbating a decline in genetic diversity.

Tragedy without warning

By late May more than 600 tiny tadpoles were still present in an isolated, 18-foot stretch of the ditch. And then, without warning -- tragedy! During June, western Maryland was buffeted by a series of intensive rain storms. Swollen creeks and rivers inundated low-lying farms and settlements. Torrential runoff scoured the breeding site, causing the delicate larvae to cascade down the adjacent mountain side. In a matter of minutes an entire year's reproductive effort was gone, and with it, the fate of the population was sealed.

The possible extirpation of mountain chorus frogs from Maryland is significant, not because it decreases the faunal diversity of a small eastern state, but because it brings into focus the more serious problem of amphibian declines on a global scale. Collectively, these declines remind us that we are, without doubt, ratcheting toward a silent spring -- a reality that should cause each reader and reflect on last stanza of Paul Simon's unintended environmental metaphor:

''Fools, said I, you do not know, silence like a cancer grows./ Hear my words that I might teach you, take my arms that I might reach you./ But my words like silent raindrops fell and echoed in the wells of silence.''

Don C. Forester professes biology at Towson State University.

Pub Date: 3/26/97

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