Arm Inner wing between body and carpal joint (often used for raptors).
Brownhead Term applied to encompass female, juvenile and immature plumages of Smew, Red-breasted Merganser and Goosander.
Chum Revolting mixture of dead fish, fish oil and, sometimes, popcorn poured onto the sea to attract seabirds on pelagic trips.
Culmen The ridge along the top of the upper mandible of the bill.
Eclipse Non-breeding plumage of male ducks in late summer.
Filoplume A hair-like feather.
Gonys The ridge of the lower mandible between the gonydeal angle and the bill tip (often used in reference to large gulls).
Gular Pertaining to the throat.
Hand Outer wing between carpal joint and tip (often used for raptors).
Leucism All-white plumage or all-white feathers mixed with normal-coloured ones. Always normal-coloured eyes. Other colour aberrations (such as black plumage that is normally pale brown) have a variety of terms; see van Grouw (2013).
Overshooting When a migrant bird flies further than it should (e.g. a Subalpine Warbler heading from Africa to Spain, but ‘overshooting’ to Britain.)
Pishing ‘Shushing’ noise made by birdwatchers to attract warblers and other small passerines.
P10, P9 etc. The primaries on some species, particularly gulls, are referred to by a letter and number, P10 being the outermost primary, P9 the second outermost and so on to P1, which is the innermost primary immediately adjacent to the secondaries. Confusingly, this system is usually reversed in passerines, where the outermost primary is referred to as P1.
Rectrices Main tail feathers.
Remiges Main flight feathers (primaries and secondaries).
Tertial crescent Large white crescent-shaped fringe to the closed tertials, seen on adult gulls at rest.
Tertial step Refers to a distinct ‘step’ on the closed wing between the tertials and the primaries when viewed side-on (commonest on large gulls).
Wreck Occasional disaster affecting seabirds that are swept ashore or inland by gales and/or food shortages.