Unusually for a bird with such a large range, it has no geographical subspecies if the possibly conspecific duck Eaton's pintail is considered to be a separate species.

This is a large duck, and the male's long central tail feathers give rise to the species' English and scientific names.

[8] A claimed extinct subspecies from Manra Island, Tristram's pintail, A. a. modesta, appears to be indistinguishable from the nominate form.

[8] In non-breeding (eclipse) plumage, the drake pintail looks similar to the female, but retains the male upperwing pattern and long grey shoulder feathers.

Juvenile birds resemble the female, but are less neatly scalloped and have a duller brown speculum with a narrower trailing edge.

[14] The male's call is a soft proop-proop whistle, similar to that of the common teal, whereas the female has a mallard-like descending quack, and a low croak when flushed.

[8] This dabbling duck breeds across northern areas of the Palearctic south to about Poland and Mongolia,[12] and in Canada, Alaska and the Midwestern United States.

In winter, it will utilise a wider range of open habitats, such as sheltered estuaries, brackish marshes and coastal lagoons.

[12] Among the earliest species to breed in the spring, northern pintails typically form pairs during migration, or even while still on wintering grounds.

[17][18] Breeding takes place between April and June, with the nest being constructed on the ground and hidden amongst vegetation in a dry location, often some distance from water.

[19] The pintail feeds by dabbling and upending in shallow water for plant food mainly in the evening or at night, and therefore spends much of the day resting.

[8] Its long neck enables it to take food items from the bottom of water bodies up to 30 cm (12 in) deep, which are beyond the reach of other dabbling ducks like the mallard.

[13] During the nesting season, this bird eats mainly invertebrate animals, including aquatic insects, molluscs and crustaceans.

[12] Pintail nests and chicks are vulnerable to predation by mammals, such as foxes and badgers, and birds like gulls, crows and magpies.

The adults can take flight to escape terrestrial predators, but nesting females in particular may be surprised by large carnivores such as bobcats.

[26] The northern pintail is a popular species for game shooting because of its speed, agility, and excellent eating qualities, and is hunted across its range.

[19] Populations are also affected by the conversion of wetlands and grassland to arable crops, depriving the duck of feeding and nesting areas.

In 1997, an estimated 1.5 million water birds, the majority being northern pintails, died from avian botulism during two outbreaks in Canada and Utah.