The rest of the upper parts, including the head, neck, and breast, are coloured black to blackish brown.

In its non-breeding plumage, this bird has greyish-black upper parts, including the top of the head and a vertical stripe on the back of the neck.

Insects, which make up the majority of this bird's diet, are caught either on the surface of the water or when they are in flight; this species occasionally practices foliage gleaning.

[2] The genus name Dytes is sometimes used for this species and its closest relatives,[4] a placement which was preferred by Robert Ridgway in 1881.

The extinct Colombian grebe P. andinus is particularly closely related, and is often considered to be a subspecies of P. nigricollis; it is genetically nested within it.

[17] The nominate subspecies in breeding plumage has the head, neck, breast, and upper parts coloured black to blackish brown, with the exception of the ochre-coloured fan of feathers extending behind the eye over the eye-coverts and sides of the nape.

[4] The thin, upturned bill,[19] on the other hand, is black, and is connected to the eye by a blackish line starting at the gape.

The upperwing is blackish to drab brown in colour and has a white patch formed by the secondaries and part of the inner primaries.

The underwing and abdomen is white, with an exception to the former being the dark tertials and the mostly pale grey-brown outer primaries.

[20] This species breeds in vegetated areas of freshwater lakes across temperate Europe, Asia, eastern and southern Africa, interior southwestern Canada, and the southwest and western United States.

[21] Then, after completing the moult and waiting for sometimes several months,[22] it migrates to winter in places such as the south-western Palearctic and the eastern parts of both Africa and Asia.

[22] When not breeding, its habitat is primarily saline lakes, sheltered inshore seas, and coastal estuaries.

When advertising for a mate, a black-necked grebe will approach others of its species with its body fluffed out and its neck erect.

[27] Even though the young can swim and dive during this time, they rarely do, instead staying on the parents' backs for four days after hatching.

[20] This behaviour is present in all grebes, and is likely to have evolved because it reduces travel costs, specifically those back to the nest to brood the chicks and give them food.

[32] Predation is usually not the primary cause of egg loss, with most nesting failures occurring after the chicks have hatched.

[34] When feeding on brine shrimps at hypersaline lakes, it likely uses its large tongue to block the oral cavity.

[35] It also forages by gleaning foliage, plucking objects off of the surface of water, having its head submerged while swimming, and sometimes capturing flying insects.

[4] This grebe eats mostly insects, of both adult and larval stages, as well as crustaceans, molluscs, tadpoles, and small frogs and fish.

[38] The moult migration is dangerous, with hundreds and sometimes thousands of birds being killed by snowstorms when traveling to places such as Mono Lake.

[38] This additional fat is used to power the black-necked grebe's overnight fall migration to its wintering grounds.

[41] Migration usually starts earlier when shrimps are more abundant and when the moulting lake is at a higher than average temperature.

[38] However, when migrating, it travels as much as 6,000 kilometres (3,700 miles) to reach rich feeding areas that are exploited by few other species.

[43] In flight, the shape of this grebe is like a loon: straight neck, legs trailing, and wings beating often.

[20] When diving, this bird pulls its head back and then arches it forward into the water, with the body following and a slight springing.

In 2013, at the Great Salt Lake, for example, there was an outbreak of West Nile virus which caused one of the largest recorded avian die-offs in the US.

[45] Avian cholera, another disease that can cause massive die-offs in this species,[45] is transmitted by currently-unknown biotoxins and/or pathogens, as well as problems with feather waterproofing putting birds at risk.

[4] Unknown biotoxins, pathogens, and the impairment of feather waterproofing can lead to hypothermia and avian cholera.

These and other factors, such as human disturbance, including collisions with power transmission lines, contribute to declining populations in certain areas.

This species used to be threatened in North America by the millinery industry, which helped facilitate the hunting of the birds, and egg collectors.