Martha’s Vineyard provides a winter home for sea ducks of all varieties

The largest number of ducks often remain on the water just off land, but recent weather conditions have forced them into local bays.

Photo by Matt Pelikan

Regardless of how harsh a winter is, Martha’s Vineyard is always the seasonal home for a lot of ducks. Our productive bays, ponds, and shoals invariably attract scoters, eiders, mergansers, buffleheads, and other “sea ducks” by the thousands, sometimes the tens of thousands.

This invasion of avian seasonals may not be all that apparent to the non-birder: The largest rafts of ducks spend much of their time feeding or just bobbing on the swells a long way offshore, and even many thousands of ducks, spread out along our lengthy shoreline, doesn’t look like much if you’re not paying attention. But the right weather conditions hitting at the right point in the season can dramatically alter the picture, concentrating ducks in highly visible areas, swelling duck numbers, and changing the mix of species that is present.

A good, vicious cold snap in late winter invariably does the trick, especially if storms and heavy snow are involved. Sound familiar?

In a dramatic but utterly predictable phenomenon, the past few weeks have seen a notable increase in the numbers of certain duck species, coinciding with an equally dramatic change in duck distribution and behavior. As tough and hardy as these birds are, freezing water effectively represents a loss of habitat for them, and in weather like we’ve been having, large numbers of wintering waterfowl have suddenly moved south, concentrated on remaining areas of open shallow water, or both.

In particular, scaup (“bluebills” to many Islanders, especially those who hunt) typically start the winter in large numbers not far north of us, on ponds both inland and coastal. Scaup also winter routinely in modest numbers on the Island’s Great Ponds. But when the ponds on the southeastern coastal plain of mainland Massachusetts, across the water in Barnstable County, or on the Vineyard itself, lock up, rafts of scaup (there are two species, but never mind) must relocate.

Favored destinations include openings of embayments and other shallow but productive sites where tidal flow or even vessel traffic keeps the water open. And so, for example, scaup flocks have recently turned up on a small unfrozen portion of the Lagoon, where they are readily visible from the municipal boat landing.

These birds are surely reserving the right to move farther south: Ducks can easily travel hundreds of miles in a day if they feel the need. But clearly scaup wintering in our region have committed, in some dim, birdy way, to a strategy of investing as little energy as possible in migrating. If they can stick out a week or two in temporary quarters, conditions will likely moderate and allow them to begin the move back toward their breeding grounds. Their boldness may translate to an early arrival, and perhaps a better chance of reproducing than birds that moved farther south.

Other species have been on the move, too, though some species are more affected by harsh winters than others. Scaup and some of the smaller sea ducks, notably buffleheads, prefer to feed in relatively shallow water, which of course is what freezes up first. Hence, we get a surge of these species. Common eiders, in contrast, don’t care much at all about the weather: Massive, famously insulated, and comfortable in deep water whether feeding or resting, they often don’t seem to react at all to a cold spell.

Overall, then, duck numbers have increased, more so with some species than with others. And ducks in general (but again, some species more than others) have gravitated to a limited number of sites, many of which, happily for a birder, are easily accessible.

Last Thursday inside the opening of the Lagoon, I found about 250 scaup (mostly in one large raft, closely packed as is typical of bluebills), two dozen common goldeneyes, roughly 30 red-breasted mergansers, 50 buffleheads, and smaller numbers of another four or five species. A single Barrow’s goldeneye, uncommon on the Vineyard, was the highlight of the mix.

Similarly, as the noon ferry unmoored in Woods Hole on Saturday, a dozen species of ducks were visible from the weather deck. Again, scaup were by far the most common: Several flocks of a couple of hundred each were stretched out along the waterfront, where, I think, they were picking mussels or other edibles off the submerged portions of seawalls and pilings. The Woods Hole channel itself was alive with long-tailed ducks, goldeneyes, and common eiders.

Waterfowl concentrations like this are short-lived, dispersing as soon as conditions moderate, and they don’t occur every winter by any means. But they offer a chance for good looks at a diverse mix of ducks — with, if you’re lucky, something unusual thrown in. For me, they’re also a reminder of how specific the seasonal needs of a migratory species can be: It may only matter for a few days or weeks, but the overlap of productive waters and fast currents offers a temporary refuge that tides these birds through a harsh season.