Following the Birds on Pristine Block Island

Like its geological cousin the mountain, a small island is best appreciated as a point in space. It sits as its own center of things, offering firm footing from which to look out, or in.

When it comes to refuge, however, they part company. Islands provide it. Mountaintops don't.

Block Island sits some 12 miles off the coast of Rhode Island, a gravelly piece of land with wind-swept bluffs and green meadows crisscrossed by 300-year-old stonewalls.

Just 6,400 acres, this glacial deposit girdled by sand cliffs has an incredible 365 freshwater ponds (one for each day of the year, the locals like to tell you). It is also home to 700 species of plants, including the endangered northern blazing star.

Historic lighthouses at Block Island's northern and southern tips still guide ships approaching Long Island Sound. A small harbor is accentuated by the white wood faades and mansard roofs of half-a-dozen grand old hotels that beckon ferries laden with the urban weary.

The island is best known as a haven for East Coast vacationers. Not so well known is that for millennia, juvenile (less than a year old) birds have migrated south in the autumn and stopped here. Just as summer tourists come to pause and rest before getting on with their lives, so do the birds, including warblers, tanagers, catbirds, chickadees, and peregrine falcons.

And where birds flock, birders follow. Patrick Dorcus is manager of the Moose Hill Audubon Sanctuary in Sharon, Mass. Each autumn he guides birding groups visiting Block Island. A Maine native, he knows the migrating habits of most North American birds. For seven years he helped manage the two Audubon sanctuaries on Block Island, giving him intimate knowledge of the island's remarkable biological diversity.

Immature birds have never made the long flight south, he points out. They have no memory of overland routes, and they usually miss the departure by flocks of mature birds. They leave when a change in temperature triggers an instinctive need to travel south. The coastline becomes both road map and flight path.

Traveling mainly at night, the birds migrate down the New England coast. As they pass over Block Island, the vast expanse of the Atlantic opens up to them. They become disoriented, circle back on the island, and land on its southern bluffs in fields and woods. (Hawks are often waiting to take advantage of this confusion.)

With the next day's early light, the migrating birds wing their way back up the seven miles to the northern tip of the island, gather themselves, and then venture off due west, straddling the Connecticut shoreline and Long Island Sound until they can see across Long Island, from New York to New Jersey, where they then veer due south again.

In addition to taking the annual bird census, Mr. Dorcus spends many hours saddled to a tractor mowing waist-high grasses - part of a restoration effort for the orange-red American burying beetle, an insect on the federal register of endangered species.

The beetle needs wooded areas adjacent to open fields for breeding, says Dorcus. It crawls out from the woods at night, squirms under some "small dead animal in the grass to dig the earth out underneath it," he says, then lays its eggs in the carcass before retuning back to the woods. In the 17th and 18th centuries, fish thrown in the fields by Yankee farmers as fertilizer established the beetle population.

The crawling undertakers "serve as an indicator species," says Dorcus, and when they are healthy and prospering, "all kinds of other good things" are happening for migrating birds and plants.

The same can be said for small islands and people who visit them: When pristine and prosperous like Block Island, many good things happen for visitors.