The vast harborside flats beckon on a beautiful June evening. It is a very low tide, and my dog and I luxuriate in the wet sand. What a lovely feeling to be squishing my toes in the underbelly of the bay.
There are no people here, but we are not alone. Scattered around us are roughly a dozen common grackles, strolling about, not in a flock, but spaced out as individuals or sometimes pairs.
Actually, “strolling” is not the correct verb. They are patroling, their glossy heads pointed downward as they intently scan the flats between their feet. Occasionally, they dart at something. I see one or two tug worms from the wet sand, reminiscent of robins feeding on a lawn. They are probably also looking for snails, crabs, shrimp, and other tiny intertidal creatures. A couple of these birds fly with their prey landward, perhaps back to their nests to feed their young.
What is going on here? Grackles are not shorebirds. Aside from our piping plovers, most shorebird species are far to the north, up in Hudson Bay and beyond, and are not due here until later in July. But these grackles are acting like shorebirds, even though they nest in dense shrubs and trees some distance from the water.
There is no mystery about why these birds are here: food, and plenty of it. Grackles are great opportunists, extremely resilient and adaptable. They were persecuted, and their numbers greatly reduced, by our colonial predecessors because of their supposed depredations of crops. And yet they persevered and now arrive on the Cape by the thousands in the spring. (They are not the only opportunists. I see sparrows, finches, and doves diving into the rock jetties and searching through the wrack on the beach.)
These birds remind me that the connection between sea and land is strong. Another reminder is the huge yellow swaths we encounter out on Stellwagen Bank on whale watches. What is that — pollution? passengers ask. Pollen, I tell them — tons and tons of pine pollen that waft from the trees in the spring, irritate our nasal membranes, coat our cars and lawn furniture, and head out to sea. Less visible products of the land also go seaward: fertilizer, herbicides, and plastic particles.
In a way, we are all grackles. About 40 percent of the world’s human population lives within 100 kilometers (60 miles) of the coast; throw in the shorelines of lakes and rivers, and certainly more than half of humanity is coastal. And, while our early ancestors evolved on the African savannahs, there is evidence that major droughts drove human populations to shorelines and marshes, where they discovered the bounty of fish, shellfish, and seaweed that provided the essential omega-3 amino acids that facilitated brain development. Water is literally in our blood and exerts a great attractive force on us all. As Melville describes all mankind in Moby-Dick: “They must get just as nigh the water as they possibly can without falling in.”
This is certainly true on the Cape. Shell middens document the first summer people to visit: the Wampanoag. The first Europeans also settled along the water. Thoreau, in Cape Cod, describes Provincetown as not so much a town “but an inhabited beach.” Our economy then and now depends on the water and the interface of water and land. Look at real estate values. Pick up my modest house and plop it down in Nebraska and it loses 90 percent of its value; transport it to the waterfront and it triples in worth.
But back to what we bring to the water: recent research finds that the Gulf of Maine is the most rapidly warming body of water on the planet. The reason, in simple terms: for thousands of years the warming Gulf Stream heading north and the cooling Labrador Current heading south have struck a balance, creating stable temperatures. In recent decades, the Gulf Stream has continued to plow north (bringing us blue crabs, black sea bass, sea turtles, and even a couple of manatees) while the Labrador Current has weakened. What has brought about this weakening? The melting of Arctic ice and the resulting infusion of fresh water, which diffuses the cold south-going current.
Now, a recent NASA study, based on satellite and surface sampling, documents a 65-percent decrease in the gulf’s phytoplankton productivity. These tiny green organisms are the base of the food chain for all life in the sea (and, therefore, for our “blue economy”) and for over half of our atmosphere’s oxygen. So, our addiction to fossil fuels is contributing to the inexorable warming of our beloved ocean, so taken for granted yet necessary to our very lives.
The tide advances, ankle deep. The grackles retreat gradually; they adapt, as they always have.
Will we be able to do the same?