Among the stranger-looking birds, grebes are highly adapted to life on and in the water. Their legs are set far back on their bodies — efficient for swimming but problematic on dry land, where a grebe is reduced to pushing itself awkwardly along on its belly. Grebe feet, rather than being truly webbed with skin stretching between the toes, are unique, with flexible lobes of flesh along the sides of each toe. Grebes can fly, but don’t make it look easy; their heavy bodies demand incessant, rapid wing beats to generate enough lift, and an airborne grebe looks to be in a constant state of mild panic.
In their preferred element, though, grebes are masterful. Those ludicrous legs and feet propel their owner with fishlike ease. Grebes can dive to substantial depths, and routinely stay submerged for a minute or more; if you’re watching a grebe, it often pops to the surface an unbelievable distance from where you saw it submerge.
Due to their structural similarity, grebes and loons were long presumed to be closely related, and many field guides still present them on adjacent pages. But genetic analysis suggests that the actual relationship between these aquatic divers is not close. In fact, the closest living relatives of the grebes, as implausible as it may sound, appear to be the flamingos. In any case, grebes are among the most ancient extant birds, a tried and true design that debuted millions of years ago.
Five species of grebes have occurred on the Vineyard, but two of these — eared grebe and western grebe — are rare enough vagrants from the west, with just a few Island records, so that we can set them aside. The remaining three species all occur here regularly, but generally in small numbers; there are exceptions, though, especially with the more oceanic pair of species.
The tiny pied-billed grebe, so named for a dark ring that encircles its stubby beak, is a compact, brownish bird of fresh water. Crackatuxet Cove on the Edgartown Great Pond and the head of the Lagoon are classic Vineyard locations for this species, and one or two individuals can often be found in one or both locations from October until the water freezes. Squibnocket Pond is another reliable location. But while this jay-size bird can be found dependably, I can’t recall ever seeing more than a half-dozen or so in a day on the Vineyard.
Our other usual grebes, red-necked and horned, occur almost invariably on salt water. Individuals or small groups sometimes turn up in the Island’s harbors (scanning from the Eastville Beach parking lot is a good bet). But the largest numbers of these species typically occur on open waters off State Beach or the South Shore. Often, they’re feeding right in the surf zone, presumably preying on small fish and invertebrates stirred up by wave action. Other times, they are far enough from land to be difficult to spot.
Red-necked grebes, as their name suggests, are colorful birds in breeding plumage. And horned grebes truly do sport feathery “horns” in the breeding season. We do see partial breeding plumage on some late-winter birds, but mainly, we get grebes in their drab winter feathers, gray above and whitish below. Since grebes are often viewed at long range, structure may be the best way to distinguish the two species, with red-necked substantially larger and more robust than horned.
Numbers are typically modest; a dozen horned grebes in a day is good work, as is anything more than one red-necked. But once in a while, flocks of migrants settle in. I’ve counted 400 horned grebes in a dispersed flock off State Beach, and Vern Laux and I once tallied 220 red-necked grebes from a vantage point just west of Lucy Vincent Beach in Chilmark.
Despite their awkward demeanor in the air, grebes are strongly migratory birds that cover long distances in remarkably little time. Horned and red-necked grebes both breed in the continent’s Northwest, nesting by potholes and freshwater wetlands from the prairie provinces up into Alaska. They winter mainly along the coasts, with significant portions of their populations working their way through the Great Lakes and then making a rapid flight to winter along the Eastern Seaboard. Wintering birds concentrate off New England, but can be found from the Maritimes to roughly the Carolinas (red-necked) or the Gulf of Mexico (horned).
I’ve gone for entire seasons without seeing a single horned or red-necked grebe; other years, they’re present through the entire winter in modest numbers. It often seems like the entire population moves around constantly during the winter. These birds are highly gregarious at times, perhaps especially before they launch on the return migration to their breeding rounds. Such aggregations in late winter account for most of the high counts of grebes on the Vineyard. But it’s clear that the locations where these species stage for their journey vary widely from year to year, according to rules that are presumably clear to the grebes, though they leave me baffled.
As we emerge from the coldest part of the winter, East Coast grebes are ramping their inscrutable preparations for migration. February and March are prime grebe time on the Vineyard, and it’s worth making the effort to find and observe these ornithological oddities.