The tide goes out for miles. Not the dramatic drainage of a harbor—no rush, no roar—but the quiet withdrawal of water from salt grass, from the mud flats, from the thousand small channels that hold the shape of every current that has ever moved through here. What remains is not emptiness. The flat exposes itself the way a sentence does when you finally read it right.
A great blue heron stands in six inches of water at the edge of the Rowley River, motionless in the way only a heron can be motionless—not patient, which implies waiting, but genuinely still, the way a stone is still. It has been there long enough that the birds behind it have stopped noting it. A tern crosses overhead without looking down.
This is mid-March. The Plum Island refuge is mostly closed to visitors until the piping plovers arrive and the closure expands to protect their nests, but today the parking lot at the northern end is open and nearly empty. One truck with Massachusetts plates. A birder in a green jacket working a spotting scope on a tripod, her notebook open on the hood of the truck, writing something in a hand too small to read at any distance. She has been here since before the sun cleared the dunes. She does not look up.
The light in March in this part of the world is a kind of argument. It suggests warmth with its angle—the gold of late afternoon, even at noon—but the wind off the Atlantic has not consulted it. Spartina grass, the marsh cordgrass that covers the flats in summer, stands now in its dead form, the brown that is almost copper when the light catches it exactly right. It bends in the wind and springs back. It has been doing this all winter. It will do it for another six weeks before anything green pushes through at the base.
Out on the mud, the sanderlings run. They always run. This is a fact about sanderlings: they do not walk, they sprint in small bursts, following the water’s edge as the waves advance and withdraw, eating whatever the water uncovers. A dozen of them working a hundred feet of shoreline, legs a blur, appearing to panic and then appearing to be fine, appearing to panic again. If they have an inner life it is organized around the immediate. The wave. The small crustacean. The wave again.
There is a house near the southern end of the island that has been there since the 1940s. Every winter the Atlantic takes more of the dune in front of it. The pilings have been exposed, the beach stairs replaced twice. The family that owns it—a family from Andover, a family that had money once and now has considerably less of it—comes in the summer and spends two weeks arguing about whether to sell. They do not sell. The children have memories of catching fiddler crabs in the marsh behind the house. The father remembers his father casting off the beach at dawn. These are the things that make a place impossible to leave even after it has started to leave you.
The heron moves. Not in response to anything visible—no fish, no threat—just a slow rearrangement, three long steps forward, the head dropping slightly toward the water. Then still again.
At the visitor center, a laminated placard explains the ecology of the salt marsh. It uses the word productive several times. The marsh is highly productive. What this means is: the cordgrass dies and decomposes, the bacteria thrive, the invertebrates eat the bacteria, the fish eat the invertebrates, the birds eat the fish, and the whole arrangement is supported by the daily rhythm of water coming and going, bringing nutrients from the ocean, taking the detritus out to sea. The marsh does not try to be productive. It simply is what it is, and what it is happens to sustain a great deal.
By three in the afternoon the tide is coming back. The channels fill first—you can watch the water moving inland through the network of cuts in the grass, covering the mud, climbing the stalks of last year’s spartina. The heron has moved half a mile south without anyone seeing it go. The birder has packed up her scope and is eating a sandwich in her truck, windows cracked, binoculars still around her neck.
The light is going gold now, actually gold, the low sun throwing long shadows across the dunes. The piping plovers are somewhere south of here, in Georgia or the Carolinas or further. In six weeks they will arrive and the closure will go up and the restricted section of beach will become, for the season, theirs. The wardens will count nests. They will do this carefully, marking the locations, checking them every few days. The fencing is low—just rope and small wooden stakes—but the plovers stay inside it and raise their young in the scrapes of sand between the clumps of grass.
The heron stands somewhere in the marsh to the south. The sanderlings are still running. The water is coming back in.
What the marsh produces, more than anything, is time—the sense of it, the long slow fact of it, the way the tide has been doing this since before the first house was built on the island, since before there was anyone to watch the heron stand still in the shallows and think: look at that.
The birder finishes her sandwich. She picks up her binoculars. She looks.