A spring fancy for the great blue heron


March 05, 1994|By TOM HORTON

NANJEMOY -- From deep in the Southern Maryland woods, where the Potomac's great bend sculpts the western bulge of Charles County, a breeze wafts the sounds of spring's first symphony.

Sounds of a ravening, demented mob. Howling. Screaming. Moaning. Croaking. Growling. Whooping. Gargling with oyster shells.

A soundtrack for "Jurassic Park": a rasping, clacking melange of fricatives and gutturals, belonging to a time not of this Earth's.

If you did not know what you were hearing, you would likely turn and run, groundhog-like, to the car, back to another month of winter.

DTC But to the initiated, these are sounds to savor like new wine -- a lusty potion, primordial bouquet, with hints of baying wolf and moonlit swamp.

Official spring is weeks away. But if you must rush the season, Nanjemoy is the place to be, and the sound's sources -- a couple thousand courting, mating, nesting great blue herons -- are the birds to see.

Though they nest in about 200 spots around the Chesapeake Bay, it is to these woods that nearly one in every 10 of the bay's 27,000 great blues returns. They come from across their wintering grounds in the Southeast, urged by the lengthening light that signals spring every March 21, when the day pulls even with the night for the first time since September.

It is always around Valentine's Day when they arrive, never more than a few days early or late, according to Calvert Posey, who has been watching them here for 50 years. Ice and storms do not delay them, he says. It is by the less fickle clock of the "photoperiod" -- the length of the day -- that the birds seem to set their schedule.

On four memorable Februaries, Posey was actually there the moment the great birds arrived. It was always around sunrise when a lone heron would drift in from the southwest and circle the nests, calling gutturally but making no attempt to light. Then, within 20 minutes, great numbers would appear, gliding on 7-foot wings, descending to the hundreds of nests in the tops of the big oaks and pines and beeches.

To enter a heron rookery is to connect with a time when the Earth was much younger. Great wings flail the air like flapping bedsheets as the birds curse the intruder with language learned from pterodactyls. Some remain in the highest treetops, stark and elemental as runes.

I think of the great blues as ancient wings. The true and literal ancient wing was archaeopteryx, a crow-sized, feathered dinosaur that lived and feebly flew 130 million years ago, the forerunner of all modern birds.

Today's herons have not changed greatly since their family, the Ardeidae, which includes egrets and bitterns, evolved some 60 million years ago. They retain more of reptilian archaeopteryx than most birds, and ancient wing seems to me to suit them fine.

Posey, who has lived here for almost all of his 70 years, is as much a spirit of this place as the herons, whose nesting territory he was instrumental in protecting.

He has farmed the land and timbered it, trapped its marshes and creeks, studied its plant life and the history of native Americans and colonists here.

He is that rarest of persons who understands the full scope and value -- not just acres and prices -- of the community in which he lives.

He recalls when the herons first came to nest here. Though their franchise on the planet goes back to the mists of time, they have existed here and elsewhere within a context of near-constant change.

He was combining wheat one day, probably in 1943, when he saw the big birds flying all around him in numbers he had never observed before, Posey says.

They had established a new rookery in the vicinity. Later, Posey would connect the event with the clear-cutting a year before of an established heron nesting area on the Mattawoman Creek in another part of the county. It had been cut for a pig farm.

That was just one among many greater shifts in Charles County's land use, according to Posey. During the last few centuries, this section of the county has gone from totally forested, to mostly cleared for growing grain and for the fox hunting pleasure of the gentry and now has reverted to where Charles is Maryland's third most forested county, next to Garrett and Allegany.

Beaver have gone and come again. In recent years they have damaged and killed many of the fine old nest trees within the heron rookery. And muskrat, which Posey trapped in his younger days, have plummeted as the rising sea level has altered the vegetation of local marshes.

All these changes, and more: Yet the herons flourish. Their present rookery has grown from 100 or so nests in the 1940s to more than 1,300 this year.

Lately, the sheer volume of their droppings, combined with beaver activity, has thinned out enough trees to make the birds shift the boundaries of their nesting area. Many already are outside the 273 acres of the Nanjemoy Creek Great Blue Heron Sanctuary, which at Posey's urging, the Maryland chapter of The Nature Conservancy preserved about 15 years ago.

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