Friday, 3 January 2014

Black-throated Diver (Gavia arctica)

Winter plumage adult Black-throated Diver (subspecies G. a. arctica) at Swithland Reservoir, Leicestershire - January 2014

OTHER NAMES: Arctic Loon, Black-throated Loon
Featured Subspecies: Gavia arctica arctica
Weight: 2-3.2kg
Length: 68-73cm
Wingspan: 120cm
UK AMBER LIST / LEAST CONCERN - IUCN Red List

Also known as the Arctic Loon and the Black-throated Loon.  Theoretically at least, the black-throated diver is the rarest of the three divers found regularly in the UK, but as I've found the theoretical easiest to track down the hardest to find (the red-throated) I wouldn't read too deeply into that information.  The divers generally seem to be fairly frustrating to get hold of unless you have the fortune to live in the places they turn up; generally along the coast or at certain reservoirs - trying to make one off trips to catch up with them often results in them not being found when you get there.  The black-throated diver itself is intermediate between the great northern and red-throated - the Summer plumage of any should be fairly easy to differentiate but in the Winter plumage, the beak is probably the best quick diagnostic to go from - the Great Northern has the sword like proportions of heron bill, the black-throated is more slender and like a grebe and the Red-throated has a distinct upwards turn to it.

 - Related Species -
ORDER: Gaviiformes
FAMILY: Gaviidae
GENUS: Gavia
SUBSPECIES: G. a. arctica, G. a. pacifica, G. a. viridigularis

 - Sighting Locations -
UNITED KINGDOM - Scarce Breeding Species (190-250 pairs) and Scarce Winter Migrant (approx. 560 birds)
 - Vagrant bird seen at Swithland Reservoir (1 Winter plumage adult in 2014) .

Further Notes: RSPB, Wikipedia, BirdGuides, BirdForum Opus, Arkive, IUCN Red List

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