Black scoter

Voice

The Common Scoter group is the one scoter group that genuinely calls at sea, and here that pays off. The drake gives a clear, far-carrying whistle. On Common Scoter it is a short, muffled pyoo; on Black Scoter the note is held far longer, slightly quavering and mournful, more of a koo-lee that seems to run on for seconds. That difference in length is reliable and has produced several British birds: heard first in a whistling raft, then picked out with a scope. Away from the March to May display period both are largely silent.

Identification

Identical to Common Scoter in size and build: a compact, wholly dark scoter with a pointed tail and no white in the wing. Adult drake: glossy black, with the entire swollen bill base bright yellow to orange, as though a large yellow blob had been pressed onto the bill; the yellow reaches back to the feathering and wraps over the top and sides of the swelling, with the rest of the bill black. The female is dark brown with pale cheek and throat cut sharply against a dark cap and a grey bill, exactly as in Common Scoter. First-winter males show almost no yellow and acquire it through their second calendar year.

Confusion species

Everything turns on Common Scoter. On a drake Common the knob at the bill base is black and the yellow is confined to a narrow strip along the culmen around and behind the nostrils; on Black Scoter the whole swelling is yellow or orange, wrapping over the sides, which makes the bill base look fuller and more bulbous. Black Scoter also averages a rounder head, with a steeper forehead and a fuller nape, but those differences overlap and never carry an identification on their own. Adult drakes are workable, even at range, as long as the bird holds its head side-on. Second calendar-year males are unreliable: a half-yellow, half-dark bill panel fits a young Common Scoter just as well. Females and first-years cannot be separated in the field, and the honest course is to leave them unidentified; no proposed character stands up.

Habitat

Shallow coastal seas over shellfish banks, always inside rafts of Common Scoter and so usually within a few kilometres of the shore. Also in tide races at inlets and off pier heads. Breeds beside lakes and tundra pools in Alaska and eastern Siberia; in Europe you will only ever see it at sea.

Range and movements

Breeds in Alaska, north-east Siberia and eastern Canada and winters on both American coasts. In Europe it is a genuine rarity. Britain has around thirty-five records, starting with Gosford Bay, Lothian, in 1987, heavily weighted to Scotland, with long-staying drakes at Llanfairfechan in Wales, at Blackdog and Murcar on the Aberdeenshire coast, at Lunan Bay and along the Northumberland coast; most involve returning individuals. The Netherlands has four records accepted by its rarities committee: Voorne in December 1954, Texel in November 1967, Voorne again in November 1977 and Schiermonnikoog in October 2021, the last bird returning in 2022 and 2023. The first three were also the first for Europe. Spain has three accepted records, in Asturias in 1986 and 1994 and in Galicia in 2002.

Where and when to look

Take a headland or a pier where big moulting rafts of Common Scoter gather in late summer and autumn, and grind through them with a scope in flat calm. Do not look for black, look for yellow: every drake that turns its head gives you a fraction of a second on the bill base. On a windless evening in March or April it pays to listen first, and a whistle that plainly outlasts the rest of the chorus is the cue to comb that corner of the raft.

Conservation status

Assessed as Near Threatened. Numbers in Alaska and eastern Canada have fallen steeply within a few decades and the causes are not well understood. Gillnet bycatch, oil pollution, hunting along the flyways and changes in the shellfish banks have all been proposed. Because the birds concentrate in dense rafts at a limited number of sites, any single incident registers immediately in the totals.