Wild Side: Odd ducks

Be on the lookout for American coots.

The American coot is usually found close to a shoreline. —Robert Pos / USFWS

If you’re fond of odd-looking birds, you’re in luck! Late fall is prime time for viewing American coots on Martha’s Vineyard. A member of the same taxonomic family as rails, the coot is one of those birds that seems cobbled together out of spare parts. Uniform gray in plumage, with oversize feet, a white bill, and virtually no tail, the coot is hard to confuse with any other species.

This bird’s distribution on the Vineyard is quirky. In seasonal terms, the coot is almost exclusively a late autumn visitor. Especially in years when the species is plentiful here, coots may linger into, and sometimes even through, the winter. But records of true spring migrants are rare here, and as far as I know, coots have never been detected breeding on the Vineyard.

Groups of coots sometimes occur here; I can recall seeing as many as 20 or 30 at a time. But more often, this species turns up as single birds or very small groups, usually found on brackish water, or freshwater close to the shoreline. In recent years, Crystal Lake in Oak Bluffs has often produced a coot or two; one or two others have often been observed at the head of the Lagoon. Squibnocket Pond often has coots. But over the long term, I can’t really think of a place that I’d consider reliable for this species; coots show up wherever they want, and that can vary from year to year, or even within a single season.

That white bill I mentioned is a handy identification cue; it’s shorter than a duck bill, and helps distinguish a coot from the true waterfowl it will often associate with. Coots also show a notably upright and buoyant posture on the water, again looking very little like ducks.

The coot’s biggest secret is surely its feet. Long, thick-boned legs seem far too large for this medium-size species. When seen clearly, the feet are not webbed, like a duck’s feet, but rather lobed: Each toe has loose flaps of skin, unconnected to the adjacent toes, but working like webbing to make the feet effective paddles. Clunky appearance aside, lobed toes let coots swim well and dive with gusto.

The partial webbing of a coot’s foot has other advantages. Since their toes can operate freely and individually, coots are adept at walking, or even climbing, in vegetation. The lobes of skin are even said to function like snowshoes, helping support the bird when it’s walking on mud. The chicken-like, head-bobbing gait of a coot may look awkward, but this species can move quickly, and cover a lot of ground on dry land if it wants to.

The feet even play a role in flight, partly replacing the coot’s nearly absent tail as a control surface. These birds fly fast and directly once up to speed, but getting airborne takes effort: Coots run along the surface to gain sufficient airspeed, and on flights too short to reach their full velocity, a coot is a sorry sight, flapping frantically and dangling its gawky legs as it struggles to stay aloft.

We have plenty of duck species that are capable of diving: Scaup, buffleheads, goldeneyes, mergansers, and all the other “sea ducks” feed by diving for invertebrates, small fish, or aquatic vegetation. But most of our “puddle ducks” — mallards, teal, wigeon, for example — either don’t dive at all, or do so sparingly. These are the ducks that coots associate with most often, and it’s often the sudden submersion of a bird in a distant group of puddle ducks that tips me off to the presence of a coot.

Except during the breeding season, when they take quantities of insect and aquatic invertebrate prey as a protein source for their young, coots are largely vegetarian. The ability to dive lets coots forage in relatively deep water, taking food from beyond the reach of many duck species. And so a foraging coot, when it pops to the surface after a dive, often finds itself surrounded by freeloading ducks! The ducks may simply snap up plant material the coot drops or disturbs while it’s underwater, or they may actively rob the coot of its meal. In any case, a coot surfacing into a halo of enthusiastic wigeon is a classic scenario.

Coots breed across a broad swath of North America, with the “prairie pothole” region of the upper Midwest representing the core of their range. The species has a habitat of breeding sparsely and irregularly well outside its usual range, though, including in Massachusetts; in recent years, a few pairs have often nested in the Sudbury River Valley, and years ago there was a small breeding population in Essex County. Migrating southward and toward the coasts in fall, this numerous species can be wildly abundant in winter at favored sites on the East and West Coasts. Numbers of migrants at our latitude, though, vary from year to year, and may be declining over time.

For now, though, this avian oddity is easy to find on the Vineyard in November and December. And it’s worth seeking this species out to appreciate its unique structure and behavior.