Black-throated Diver - Gavia arctica

Field characters: Slightly larger and longer bodied than Red-throated Diver with heavier head and straight billed. Adult breeding: Crown, upper face, and hind neck grey, lower face darker grey, shading into black chin and throat. Sides of neck narrowly striped black and white; narrow half necklace of white streaks divides throat from large black patch on foreneck, latter widening towards base; neck-side stripes extend over sides of breast. Mantle and scapulars basically blue-black, relieved by 4 areas of regular transverse white spots and checks; wing and upper tail-coverts black, spotted white. Underparts white. Bill black; legs and feet grey-black; eyes red. Adult winter: Plumage darkens more than any other diver. Forehead, mantle, and scapulars uniform dark brown; darker than crown and hind neck which show greyish cast and appear paler. Underparts silky-white except for brown spots or streaks across upper throat, on sides of chest, and along top flanks. Bill grey, with darker culmen and tip. Juvenile: Like winter adult, but upperparts browner (except for blackish forehead) and less uniform, with round feather-margins grey and appearing as pale scales in good light. Bill pale grey, sometimes bluish-white with dark culmen and tip even more obvious; eyes browner than adult.

In the breeding season tends to prefer large lochs with suitable islands and/or artificial nesting platforms. In the winter it can be found round much of the coast of Britain but is more numerous in the west, particularly Cornwall and northwest Scotland.

In VC55 it is mainly seen between October and April but most likely between November and February.

The breeding distribution is mainly confined to north and west Scotland and the Outer Hebrides on large lochs with islands. In the winter it is mainly found on the coast where it can be found in small flocks in favoured locations but more likely singular.

Fairly common in restricted range during breeding and fairly common coastal visitor in some areas but uncommon in many parts.

Rare winter visitor with all records between October and April