Editing Black-throated loon (section)

==Description==
The adult black-throated loon is {{convert|58|to|73|cm|in|abbr=on}} in length with a {{convert|100|to|130|cm|in|abbr=on}} wingspan and a weight of {{convert|1.3|to|3.4|kg|lb}}. The [[nominate subspecies]] in its {{birdgloss|breeding plumage}} has a grey head and hindneck, with a black throat and a large black patch on the foreneck, both of which have a soft purple gloss. The lower throat has a necklace-shaped patch of short parallel white lines. The sides of the throat have about five long parallel white lines that start at the side of the patch on the lower throat and run down to the chest, which also has a pattern of parallel white and black lines. The rest of the {{birdgloss|underparts}}, including the centre of the chest, are pure white. The upperparts are blackish down to the base of the wing, where there are a few rows of high contrast white squares that cover the {{birdgloss|mantle}} and {{birdgloss|scapulars}}. There are small white spots on both the lesser and median coverts. The rest of the {{birdgloss|upperwing}} is a blackish colour. The {{birdgloss|underwing}} is paler than the upperwing, and the underwing coverts are white. The tail is blackish. The bill and legs are black, with a pale grey colour on the inner half of the legs. The toes and the webs are grey, the latter also being flesh coloured. The irides are a deep brown-red. The sexes are alike, and the subspecies ''viridigularis'' is very similar to the nominate except that the former has a green throat patch, instead of black.<ref name="hbw">{{cite journal |last1=Carboneras |first1=C. |last2=Garcia |first2=E. F. J. |editor1-last=del Hoyo |editor1-first=Josep |editor2-last=Elliott |editor2-first=Andrew |editor3-last=Sargatal |editor3-first=Jordi |editor4-last=Christie |editor4-first=David A. |editor5-last=de Juana |editor5-first=Eduardo |year=2017 |title=Arctic Loon (''Gavia arctica'') |journal=Handbook of the Birds of the World Alive |url=http://www.hbw.com/species/arctic-loon-gavia-arctica |publisher=Lynx Edicions |location=Barcelona |doi=10.2173/bow.arcloo.01 |access-date=28 May 2017 |url-access=subscription}}</ref> The subspecies ''viridigularis'' retains a purplish gloss, although less than the nominate.<ref name="Bent1919"/>
[[File:GaviaArctica.svg|thumb|right|Breeding, top, and non-breeding, bottom, black-throated loons]]
The non-breeding adult differs from the breeding adult in that the cap and the back of the neck are more brownish. The non-breeding adult also lacks the patterned upperparts of the breeding adult, although some of the upperwing coverts do not lose their white spots. This results in the upperparts being an almost unpatterned black from above. The sides of the throat are usually darker at the white border separating the sides of the throat and the front of the throat; most of the time a thin dark necklace between these two areas can be seen. There is white on the sides of the head that are below the eye. The bill is a steel-grey with, similar to the breeding adult, a blackish tip.<ref name="hbw"/>
[[File:Gavia arcticaLake Zeller 02.JPG|thumb|left|Non-breeding adult]]
The juvenile is similar to the non-breeding adult, but has a browner appearance. It has a buffy scaling on the upperparts that is especially pronounced on the scapulars. The lower face and front of the neck has a diffused brownish tinge. The juvenile does not have the white spots on the wing coverts, and its irides are darker and more dull in colour. The chick hatches with [[down feather]]s that range from sooty-brown to brownish-grey, usually with a slightly paler head. The abdomen is pale.<ref name="hbw"/>

The black-throated loon can be distinguished from the Pacific loon by the white on the flanks of the former.<ref name="Floyd2008">{{cite book|author=Ted Floyd|title=Smithsonian Field Guide to the Birds of North America|url=https://books.google.com/books?id=Nn3Hz6OwjTAC|date=27 May 2008|publisher=HarperCollins|isbn=978-0-06-112040-4|page=74}}</ref>

===Vocalizations===
The male, when breeding, vocalizes a loud and rhythmic "oooéé-cu-cloooéé-cu-cloooéé-cu-cluuéé" whistling song. A "áááh-oo" wail can also be heard, and a growling or croaking "knarr-knor", a sound given especially at night. The alarm call at the nest is a rising "uweek".<ref name="hbw"/>