This shot shows contrast between Pale-belled and Dark-bellied Brant (a/k/a "Black Brant" when they were separate species). Dark-bellied is the western Brant and so its appearance in Plymouth is highly unusual. A number of Pale-bellied brant can show a quite dark belly and the juvenile has a dark belly. Telling them apart involves (1) the very dark belly blending into the black chest (2) the white "necklace" goes almost entirely around the neck of the Dark-bellied and meets or nearly meets in the front whereas the Pale-bellied does not, and (3) the heavy dark barring on the sides is always present on the Dark-bellied and usually isn't as obvious on the Pale-bellied. The juvenile Pale-bellied has no white necklace and has white barring on its back and thus is readily separated from the Dark-bellied.