I first heard them this season toward the end of February, not two weeks after the Great Snow. I was rummaging through the remnants of the woodpile, hat off to the sun and shoes half sunken in mud, when I noticed the sound. It came from somewhere beyond the edge of the woods: a handful of soprano whistles, impish and clear. Even as I straightened up, wondering, I remembered.

Peepers both spook me and tickle my fancy. I can't quite believe in them. Tiny frogs awakened in the spring to thread the night with piercing chirps. Improbable. But what mystifies me is their elusiveness. They don't really inhabit the world from which we hear them, the world of our back yard and open car window. They always seem to sing from just beyond reach.

At a distance, they can sound rhythmic, like so many throated pulsations of the dark. Come nearer and the chorus dissolves into individual grace notes: little upward curves of sound. Then step close to the marshy pond from which the piping issues--louder now, a chaos of peace and trill and clacking--and suddenly it recedes; as you advance, it falls away into complete silence. You peer at the black water, the fan of brittle reeds: nothing.

I decided to seek them out. I would surprise a peeper in mid-peep, moonlight gleaming on its moist vocal sac, that protruding bubble (again, improbable) that makes a paltry frog look like an arrogant gentlemen with an enormous goiter. I would watch the music vibrating within this globe. I would see the creatures mate. I would capture a piece of the spring.

The first thing I did was consult my local biologist. Ernie Willoughby, in his office at St. Mary's College of Maryland, dwells among flowing papers and books, eyes quick behind his spectacles, mustache ready to rise with a grin. Near his desk, a cart holds specimens: skulls, a complete turtle skeleton, jars full of buoyant frogs. From Ernie and from several books, I learn the fundamentals of peeperdom.

It is the male who sings--to attract females, of course. By passing air back and forth between the distended vocal sac and the lung--via the vocal cords--these inch-long frogs produce a sound that can carry for more than half a mile. Scientists have tried to penetrate the mysteries of this love call, setting up loudspeakers at the edge of the swamp and playing tapes of peeping hordes. The females flock to the electronic cries. The males, hearing comrades, join in.

The cacophony has been anatomized. The males stagger their calls, each doing his best to distinguish himself. Not all peepers aspire to careers as soloists, however. According to peeper authority Coleman J. Goin, in an article called "The Peep Order in Peepers: A Swamp Water Serenade," Southern spring peepers form trios. They sing in waltz time, chirping As, Bs and G sharps.

Pipsqueak though they are, the males, like males everywhere, play muscle games. They'll occasionally fight for a piece of turf. Usually, though, they establish their "courtship territory" through "vocal bouts." Within one male territory, no others may peep--until, that is, the dominant male finds a mate and the couple moves off in amplexus.

Ah, amplexus. This is the frog's loving embrace. The male hops onto the female's back and clasps her at the armpits or groin. She obliges by releasing a streak of eggs, which the male inundates with sperm. It happens, at least hereabouts, between mid-February and the end of April. After that, the songs of allurement cease. The tadpoles hatch, grow and turn into frogs. They and their elders, like other tree frogs (Hylidae, the peepers' family), climb about on plants and leap after insects. A peeper can jump more than 70 times its minuscule length, snatching a bug in mid-air.

Ernie Willoughby dipped a hand into a jar of pickled frogs and lifted forth a peeper. It was a small, rubbery In Pursuit of Peepers: A Quest for Spring By DANIEL LASKIN Special to The Washington Post Letter From Southern Maryland

ST. MARY'S CITY, Md.--I first heard them this season toward the end of February, not two weeks after the Great Snow. I was rummaging through the remnants of the woodpile, hat off to the sun and shoes half sunken in mud, when I noticed the sound. It came from somewhere beyond the edge of the woods: a handful of soprano whistles, impish and clear. Even as I straightened up, wondering, I remembered.

Peepers both spook me and tickle my fancy. I can't quite believe in them. Tiny frogs awakened in the spring to thread the night with piercing chirps. Improbable. But what mystifies me is their elusiveness. They don't really inhabit the world from which we hear them, the world of our back yard and open car window. They always seem to sing from just beyond reach.

At a distance, they can sound rhythmic, like so many throated pulsations of the dark. Come nearer and the chorus dissolves into individual grace notes: little upward curves of sound. Then step close to the marshy pond from which the piping issues--louder now, a chaos of peace and trill and clacking--and suddenly it recedes; as you advance, it falls away into complete silence. You peer at the black water, the fan of brittle reeds: nothing.

I decided to seek them out. I would surprise a peeper in mid-peep, moonlight gleaming on its moist vocal sac, that protruding bubble (again, improbable) that makes a paltry frog look like an arrogant gentlemen with an enormous goiter. I would watch the music vibrating within this globe. I would see the creatures mate. I would capture a piece of the spring.

The first thing I did was consult my local biologist. Ernie Willoughby, in his office at St. Mary's College of Maryland, dwells among flowing papers and books, eyes quick behind his spectacles, mustache ready to rise with a grin. Near his desk, a cart holds specimens: skulls, a complete turtle skeleton, jars full of buoyant frogs. From Ernie and from several books, I learn the fundamentals of peeperdom.

It is the male who sings--to attract females, of course. By passing air back and forth between the distended vocal sac and the lung--via the vocal cords--these inch-long frogs produce a sound that can carry for more than half a mile. Scientists have tried to penetrate the mysteries of this love call, setting up loudspeakers at the edge of the swamp and playing tapes of peeping hordes. The females flock to the electronic cries. The males, hearing comrades, join in.

The cacophony has been anatomized. The males stagger their calls, each doing his best to distinguish himself. Not all peepers aspire to careers as soloists, however. According to peeper authority Coleman J. Goin, in an article called "The Peep Order in Peepers: A Swamp Water Serenade," Southern spring peepers form trios. They sing in waltz time, chirping As, Bs and G sharps.

Pipsqueak though they are, the males, like males everywhere, play muscle games. They'll occasionally fight for a piece of turf. Usually, though, they establish their "courtship territory" through "vocal bouts." Within one male territory, no others may peep--until, that is, the dominant male finds a mate and the couple moves off in amplexus.

Ah, amplexus. This is the frog's loving embrace. The male hops onto the female's back and clasps her at the armpits or groin. She obliges by releasing a streak of eggs, which the male inundates with sperm. It happens, at least hereabouts, between mid-February and the end of April. After that, the songs of allurement cease. The tadpoles hatch, grow and turn into frogs. They and their elders, like other tree frogs (Hylidae, the peepers' family), climb about on plants and leap after insects. A peeper can jump more than 70 times its minuscule length, snatching a bug in mid-air.

Ernie Willoughby dipped a hand into a jar of pickled frogs and lifted forth a peeper. It was a small, rubbery thing, bearing its characteristic dark cross on its back (hence its scientific name, Hyla crucifer). Its fingers, long and thin--the hand of E.T. in miniature--ended in circular pads, the "adhesive discs" used for climbing. Its eyes were lifeless dots, like the eyes of broken mice you find in traps. When I left, enlightened but still unsatisfied, the reek of formaldehyde clung to my nose.

I wanted to go out into the marsh. I had to. For my guide, I chose Bob Shaw, the lanky, modest naturalist at the Chancellor's Point Natural History Area on the St. Mary's River. One evening, at nightfall, we took flashlights and waders (mine were flimsy galoshes, actually) and descended toward the swampy pool just off the river.

As we approached, the sound of the shrilling grew louder and more eerie, as if from within an enchanted circle, like the bottomless cave of the sibyl--that ancient priestess whose prophecies were flung forth in manic babbling. We blundered through briars at the edge of the water, and the noise suddenly died. Enshrouded in the new silence we waded in, Bob off in one direction, I in another.

The shallow pool stank of decay. Stalks of swamp mallow rose in dry clumps, or formed tangles on small hummocks. In the dark, sensing the water enter my boots as my feet settled into the soft bottom, glancing up at the silhouettes of cedars that ringed the place against sky, I waited.

The silence broke: a single, tentative peep. Stillness again. Then another; and, in odd syncopation, a third and fourth. From close at hand, some graver entity gave a low, moaning gurgle, like the sound of a stomach unbending indigestion. But new flurries of peeps came and then a steady string of them; then, like applause kindling in a swollen crowd, the tumult rose about. Before I could find my wits, I was engulfed in the sound.

It stunned me. The cries penetrated my ears, vibrated within my head. For a moment I couldn't really hear the noise because I was possessed by it: I was the noise. I tried to concentrate, but there was no finding any particular peace. About me rung the clamorous voice of sheer insistence, of infinite meaningless assertion. Pure, purposeless life, declaring itself.

After a few minutes, I recovered my perspective. Now I could hear. Amid the multitude of peeps, there were occasional trills and strange clickings, and the yuk-yuk of some larger frog. Softly I crouched toward a peeping that had detached itself from the throng. It seemed to be just before me. I pictured the little thing, damp, glittering. I switched on the flashlight. Nothing was there but a tangled hummock, the peep still sounding--somewhere. I peered, in vain. I lit the water and the bottom of stalks. It was as if the marsh, raucous with cheers, was empty.

Again and again I repeated the search. I hunted peeps to my right, to my left, behind me. I scanned with my flashlight. I focused for minutes on one spot. Here were living signals, with no apparent source.

I met up with Bob Shaw again after an hour. He had managed to spot two of them. What were they like? Only little frogs, glimpsed briefly in the unreal light before dropping into the water. For a moment, I envied Bob and renewed my heart. But then I smiled. I shut off my flashlight, stood at ease, and bathed myself again in the ceaseless peeping.