Which Wild Duck Did I See? An Identification Helper

You saw a duck at the park or on the lake, it was not a Mallard, and you would like to know what it was. Pick the size, the head colour, the bill, how it fed and where you were, and this narrows twenty-two of the commonest North American and European species — using the Cornell Lab of Ornithology’s and the RSPB’s own descriptions, not ours.

Key takeaways

• The male’s head and the bill carry most of the identification. Females of many species are brown and mottled and look alike.
• Whether it tipped up or dived splits the list in half: dabblers feed at the surface, divers disappear.
• Size is judged against a Mallard. Cornell gives every species a relative-size line, and the tool uses it.
• These are the common species. A rarity, an escaped ornamental or a hybrid will not be here.

What the tool is built from

The Cornell Lab’s All About Birds pages give each species four short paragraphs — size and shape, colour pattern, behaviour, habitat — plus a relative-size line and measurements. Eighteen North American species are in the tool with that text lightly trimmed: Mallard, American Black Duck, Wood Duck, American Wigeon, Northern Pintail, Northern Shoveler, Gadwall, Green-winged and Blue-winged Teal, Canvasback, Redhead, Ring-necked Duck, Lesser Scaup, Bufflehead, Hooded and Common Merganser, Ruddy Duck, and the Muscovy in its wild and feral forms. Several of those also occur across Europe.

For Europe the RSPB’s species pages add the Mandarin, the Tufted Duck, the Eurasian Wigeon and the Pochard, with the RSPB’s identification text; the Eurasian Teal is covered by Cornell’s Green-winged Teal entry, which describes the European form. The RSPB’s measurements are loaded onto its pages after the text and could be read for the Tufted Duck only; for the other three the tool says “not published on the page as fetched” rather than borrowing a figure from somewhere else.

The matching is Quackoria’s index of that text: each species is tagged for size relative to a Mallard, the male’s head colour, the bill, dabbling or diving, and habitat, and your answers score against the tags. Size, head colour, bill and feeding style count double, and a bird that fed the other way — dived where you saw it dabble, or the reverse — loses points, because that split is the surest thing you saw. A distinctive field mark counts most; habitat counts once; and for a brown, mottled bird the head colour is left out.

Dabbling or diving

The single most useful thing to notice. A dabbling duck feeds by tipping forward, tail in the air, and almost never goes under; it sits high on the water and springs straight up into flight. A diving duck vanishes completely and comes up somewhere else; it sits low, and needs a running start to take off. Mallard, Wigeon, Pintail, Shoveler, Gadwall, the Teals, the Wood Duck and the Black Duck dabble. Canvasback, Redhead, Ring-necked, Scaup, Bufflehead, the Mergansers, the Ruddy Duck, the Tufted Duck and the Pochard dive. Dabbling vs diving ducks explains the anatomy behind it.

The head and the bill

A glossy green head is a Mallard, a Northern Shoveler, a Common Merganser or a Wood Duck — and the bill separates them at once: yellow and flat, huge and spoon-shaped, thin and red, or small and red with a crest above it. A chestnut-red head with a grey body is a Canvasback or a Redhead in America, a Pochard or a Eurasian Wigeon in Europe; Cornell’s line for telling the first two apart is the Canvasback’s sloping forehead running straight into the bill. A dark head with a bold white patch is a Bufflehead or a Hooded Merganser, and a stiff tail cocked upward with a bright blue bill is a Ruddy Duck and nothing else.

Brown all over is the hardest case, because it is every female and every drake in late-summer eclipse. The tool cannot do much with “brown”; note the bill colour and the wing patch if you can. The Mallard page is a good place to learn the female pattern that everything else is compared with.

What the tool will not do

It will not identify a duck from a photograph — it has no camera and no eyes. It will not name rarities, vagrants, sea ducks, eiders, scoters or goldeneyes, the domestic breeds that turn up on park ponds, or the hybrids between them; the Muscovy is included because feral Muscovies are so common in parks that people search for them. And its measurements are Cornell’s “both sexes” ranges; Cornell publishes no male and female split on those pages, so the tool has none.

For a proper identification, the Cornell pages linked under each result have photographs, sounds and range maps, and the RSPB pages the same for Britain. For what the duck was doing — why it was upending, why it slept with one eye open, where it goes in October — how ducks sleep and duck migration are the reading. And if you were feeding it, the food checker says what the wildlife bodies think of that — and the duck quiz will tell you whether you already knew all this.