The sight, as I’ll explain, is hardly an unusual one. But seeing a great blue heron in winter on Martha’s Vineyard always jars my mind. These gawky birds invariably look miserable in cold weather, and you’d think that their elongated legs and neck would be vulnerable to frostbite.
And yet, there they are. This large, powerful, and versatile bird of shores and marshes is a firmly established part of the Island’s winter avifauna.
They wouldn’t be here if they didn’t have their reasons. Great blue herons, with broad wings spanning five or six feet, labor to get airborne, but once in flight row along with a buoyant directness. Any healthy member of this species is certainly capable of bailing out for warmer climes at any time.
I recently watched one of these stately gray birds as it soaked up the sun and waited for minnows to come into range along the shoreline of Tiah’s Cove. It stood perfectly still until I had nearly lost patience. Then it abruptly darted its pointed bill into the water and nonchalantly extracted, then swallowed, a small fish. The bird may have looked wretched, but it knew exactly how to play the game.
The great blue heron shows one of the more curious historical patterns that I’ve come across in Vineyard Christmas Bird Count data. For the first 11 years the count was held — 1960 through 1971 — the species was scarce, with numbers barely breaking into double digits only in 1967 (10 individuals) and 1968 (11 individuals).
But then, abruptly, numbers skyrocketed, with the 1972 count producing 59. Since then, numbers have fluctuated, occasionally dipping into the 20s, but have generally been well up in double digits. The highest count appears to have come in 1986, with a remarkable tally of 130 birds.
I’m at a loss to explain the abrupt change in status; my guess is that it reflects a sudden improvement in how effectively the species was counted, rather than an actual explosion in abundance. But multiple sources of information do suggest that wintering great blue herons have steadily increased in Massachusetts, mainly along the coast, in recent decades. My own experience, now stretching back more than half a century, is consistent with that impression.
The 1963 great blue heron species account in Arthur Cleveland Bent’s volume on North American waterbirds treats the species as scarce in winter in New England, suggesting few records at all, and none north of Boston. Even in 1993, Wayne Peterson and Richard Veit, writing in “Birds of Massachusetts,” described the great blue as “an uncommon and erratic winter resident” in the state. And the great Ludlow Griscom, in his 1959 “Birds of Martha’s Vineyard,” considered a Vineyard count of 11 birds in 1953 to be notable.
But current field guides and birding websites generally show this heron well-established in much of coastal New England, with a pattern of sparse but regular winter occurrence up into the Maritime Provinces. In coastal Massachusetts, especially in mild seasons, encountering a great blue heron in winter is no longer at all surprising.
Climate change, with its associated warmer winters in our region, undoubtedly explains part of this change. But I suspect that part of the reason may also be that the great blue heron is growing more common. Like many other heron species, this bird was hunted heavily for plumes in the 19th century, and the end of that persecution has allowed a steady recovery in numbers.
Also, nesting by great blue herons in New England is often associated with beaver ponds, with colonies of herons nesting, sometimes for many years running, in dead trees drowned by the beaver’s impoundment. As the beaver population has rebounded, more and more suitable nesting habitat for great blues has become available. Massachusetts Audubon’s breeding bird atlas project documents startling growth in both numbers and distribution in the Bay State’s breeding population of this species.
Adding to all these reasons for its flourishing, the great blue heron undoubtedly benefits from its versatility as a hunter. Wetlands, ranging from saltmarsh to pond shores to, occasionally, backyard water features, stand out as preferred foraging habitat, and fish make up the majority of this bird’s diet. But great blue herons happily feed on frogs and snakes if they’re available, and the species occasionally hunts for rodents or even grasshoppers in dry habitat.
Wintering birds on the Vineyard almost invariably turn up on shorelines, adjacent to open water, and I expect they feed almost exclusively on fish. But anything that will fit down that long, surprisingly elastic neck is fair game for this heron.
Evidence for breeding by great blue herons, even historically, on Martha’s Vineyard is sketchy at best. Griscom thinks that “cranes” reported nesting on the Vineyard by Gosnold in 1602 were probably this species. Otherwise, nesting by great blues anywhere in the Cape and Islands region is at best a rare and surprising occurrence.
But as a migrant and, increasingly, as a winter resident, this species is easy to find on the Vineyard. If you spot one, take a moment to reflect on how things can change in the natural world.