Breeding birds: 200 pairs
Wintering birds: 560 birds
In breeding plumage black-throated divers have black upperparts with white streaks. Their underparts are almost white, and their breasts are white streaked with fine black lines. They have grey heads and hind necks and the front of the neck and throat has a black patch with vertical white stripes at the side and a short collar of white spots.
They have straight grey bills, deep red eyes, and their legs and webbed feet are black.
Out of breeding plumage black-throated divers have grey-brown backs with white spots and a white patch on their flanks. They have grey crowns and napes and white forenecks bordered with fine black lines.
Both sexes are similar but the male is larger than the female.
Juvenile black-throated divers look similar to adults in winter plumage. They have spotted backs and a weak patch on their chin.
Black-throated divers breed in May and are solitary nesters. The nest is a scrape in the ground or a pile of plant matter nearby water.
Black-throated divers lay 1-3 olive-brown eggs with dark brown spots which are incubated by both parents for 28-30 days. Chicks are reared by both adults for about 12 weeks and fly at 2 months.
Black-throated divers eat mainly fish but sometimes aquatic insects, crustaceans, and molluscs.
Black-throated divers can be found in lochs in the Scottish Highlands during the summer. In winter they can be found in sheltered coastal areas throughout the UK.
The black-throated diver is also known as the Arctic loon.