The Northern pintail is a migratory duck with wide geographic distribution. This is a large bird, and the male's long central tail feathers give rise to the species' English and scientific names. Both sexes have blue-grey bills and grey legs and feet. The male is more striking, having a thin white stripe running from the back of its chocolate-colored head down its neck to its mostly white undercarriage. The male also has attractive grey, brown, and black patterning on its back and sides. The female is mainly scalloped and mottled in light brown with a more uniformly grey-brown head, and its pointed tail is shorter than the male's; it is still easily identified by its shape, long neck, and long grey bill. In non-breeding (eclipse) plumage, the male looks similar to the female but retains the male upper wing pattern and long grey shoulder feathers.
Northern pintails breed across northern areas of the Palearctic south to about Poland and Mongolia, and in Canada, Alaska and the Midwestern United States. Mainly in winters south of their breeding range, reaches almost to the equator in Panama, northern sub-Saharan Africa, and tropical South Asia. Small numbers migrate to Pacific islands, particularly Hawaii, where a few hundred birds winter on the main islands. In parts of the range, such as Great Britain and the northwestern United States, pintails may be present all year. The breeding habitat of Northern pintails is open unwooded wetlands, such as wet grassland, lakesides or tundra. In winter, they can be found in a wider range of open habitats, such as sheltered estuaries, brackish marshes, coastal lagoons, and flooded and dry agricultural fields.
Northern pintails are highly gregarious outside the breeding season and form very large mixed flocks with other ducks. They walk well on land and swim well. Pintails have a very fast flight, with their wings slightly swept-back, rather than straight out from the body like other ducks. They feed by dabbling and upending in shallow water for plant food mainly in the evening or at night and therefore spend much of the day resting. Their long neck enables them to take food items from the bottom of water bodies up to 30 cm (12 in) deep. When on land pintails feed by grazing, picking at the grain and digging out roots and tubers with their bill. These birds are generally quiet but 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.
Northern pintails are omnivores and their diet varies seasonally. In winter they eat mainly plant material including seeds and rhizomes of aquatic plants, but may sometimes feed on roots, grain, and other seeds in fields. During the nesting season, these birds eat mainly invertebrate animals, including aquatic insects, mollusks, and crustaceans.
Northern pintails are serially monogamous and form pair bonds that last only during one breeding season. Pairs usually form in autumn and winter and birds arrive together at their breeding grounds. 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. It is a shallow scrape on the ground lined with plant material and down. The female lays 7 to 9 cream-colored eggs at the rate of one per day. If predators destroy the first clutch, the female can produce a replacement clutch as late as the end of July. The female alone incubates the eggs for 22 to 24 days before they hatch. The precocial (well developed) downy chicks are then led by the female to the nearest body of water, where they feed on dead insects on the water surface. The chicks fledge in 46 to 47 days after hatching but stay with the female until she has completed molting. They reach reproductive maturity at one year of age.
The main threats to Northern pintails include avian diseases, hunting, habitat loss, lead poisoning, and predation by mammals. These birds are popular for game shooting because of their speed, agility, and excellent eating qualities, and are hunted across their range. The preferred habitat of Northern pintails is naturally susceptible to problems such as drought or the encroachment of vegetation and might be increasingly threatened by climate change. Populations are also affected by the conversion of wetlands and grassland to arable crops, depriving pintails of feeding and nesting areas. Spring planting means that many nests of these early breeding ducks are destroyed by farming activities, such as ploughing and harrowing.
According to the IUCN Red List, the total population size of the Northern pintail is 7,100,000-7,200,000 individuals. This roughly equates to 4,700,000-4,800,000 mature individuals. The European population consists of 210,000-269,000 pairs, which equates to 419,000-539,000 mature individuals. Currently, this species is classified as Least Concern (LC) on the IUCN Red List but its numbers today are decreasing.