Blue-winged teal  (Anas discors)

The blue-winged teal is classified as Least Concern (LC) on the IUCN Red List (1).

A small, distinctive species of dabbling duck, the blue-winged teal (Anas discors) has conspicuous chalky-blue upper-wing coverts lined with a bold, white rear border, and an iridescent green patch on the back of the wings (2) (3). In breeding plumage, the male blue-winged teal has a greyish or blue-grey head, with a large white crescent in front of the eye, which borders the base of the bill. The cinnamon-brown to buff underparts are densely spotted with fine black markings (3) (4) (5), and a rounded white patch is obvious on the flank. The bill is black and the legs and feet are orange-yellow (2) (3) (6). Outside of the breeding season, the male blue-winged teal exhibits ‘eclipse plumage’, moulting into a drab, grey-brown plumage, which closely resembles the female, except for a darker head with a faint outline of the white crescent in front of the eye (2) (3) (4) (5).

The female blue-winged teal is generally a plainer, mottled grey-brown overall, with a duller blue wing patch that has a narrow and indistinct white rear border. The patch on the back of the wing is mostly blackish-brown with very little green. The female has a dark line running through the eye, with small whitish crescents above and below. The juvenile blue-winged teal is similar to the adult female (2) (3) (4) (5).

The blue-winged teal breeds across North America, mainly in the prairie regions of Canada and north-central America. It is a migratory species, wintering in southern U.S., Mexico, Colombia, Ecuador and Peru, and occasionally further south to Chile. In eastern South America, the blue-winged teal also winters in Venezuela, the Guianas, Suriname and northern Brazil. It is sometimes known to winter as far south as Argentina (1) (2) (6) (7). The blue-winged teal is occasionally recorded in Europe, with most records in Britain and Ireland (5).

Generally associated with freshwater in prairies and parklands, the blue-winged teal is found in marshes, temporary and seasonal wetlands, shallow lakes, ponds and pools, and along shallow streams. It typically inhabits the shoreline rather than open water, in areas of dense emergent vegetation (2) (3) (6) (7).  In coastal areas, the blue-winged teal may occur in salt-marsh meadows with adjoining ponds or creeks (7).

During the winter, the blue-winged teal occurs on shallow inland freshwater marshes, and often also inhabits brackish or saline water bodies close to the coast, usually in tropical mangrove habitat (2) (7). 

The blue-winged teal rests on rocks protruding above water, trunks or limbs of fallen trees, bare stretches of shoreline, or on mud flats. It nests on dry ground, amid vegetation in meadows and fields that are generally close to water (7).

Foraging primarily in areas of shallow water or on mudflats, the blue-winged teal feeds on seeds, roots, grass, sedge, algae and other aquatic plants, as well as insects and aquatic invertebrates, such as molluscs and small crustaceans (2) (3) (7). Before egg-laying, the female blue-winged teal consumes large amounts of invertebrates, mostly insect larvae and snails, to provide enough energy for egg production and incubation (3). The blue-winged teal rarely dives fully below the surface, instead feeding mainly by dabbling on the surface with just the bill submerged, or by dipping just the head under the water. It will also glean invertebrates from submerged or floating vegetation (2) (3) (6).

Like other small dabbling ducks that breed in North America, the blue-winged teal forms pairs in late winter, or during the northern migration in spring (3) (6). Breeding typically begins in May (2). The female selects a territory on arrival at the breeding grounds, which is defended by the male during breeding (3). The female builds the nest just before the first egg is laid, typically selecting a well-hidden site in upland vegetation and using the feet to scrape a bowl-shaped depression in the ground. The nest is then lined with grasses found around the nest site, as well as with down and feathers (2) (3) (6).

Generally, the female will lay 10 to 12 eggs, although clutch size ranges between 6 and 15 eggs (2) (3) (7), which are incubated for 21 to 27 days (2) (7). The ducklings spend very little time in the nest, typically less than 24 hours, before making their first journey to water (3) (7). The female broods the young, although the male blue-winged teal may occasionally accompany young broods for short periods (3). The young are able to feed with out assistance from the adults, but the female remains with the ducklings for around two weeks, leading the young to appropriate feeding sites. The young blue-winged teals fledge at around 35 to 44 days old (2) (3) (6) (7). 

The male blue-winged teal leaves the breeding grounds before the female, moving to suitable moulting cover among thick vegetation, where it becomes flightless for a period of three to four weeks (7). The blue-winged teal migrates to its wintering habitats much earlier than similar species, typically departing around mid-August. The male leaves first, with the female and juveniles following by mid-September (3) (7). The blue-winged teal migrates in small flocks that display strange flight patterns composed of quick twists and turns carried out in unison (6).

The global population of the blue-winged teal has undergone a small decrease in the last 40 years, but it is not currently considered to be threatened with extinction (1) (8). The population trend of this species appears to depend on wetland conditions around its breeding grounds, with notable declines in populations following several dry years. The degradation of breeding habitat is therefore likely to be a potential threat to the blue-winged teal. In the prairie regions of the U.S. and Canada, this species’ habitat has been severely impacted by wetland drainage and grassland loss due to agriculture. In the southern U.S., habitats used by migrating and wintering birds is also threatened by agricultural development, industrial and urban encroachment, changes in water usage, and pollution (3). 

The blue-winged teal is hunted in the U.S. during special ‘September teal seasons’ that coincide with the autumn migration. Immature teal are more vulnerable to hunting than adults, but at the current levels this harvesting is not currently considered to pose a major threat to the population (3).

There are no specific conservation measures currently targeted at the blue-winged teal (1). However, this species will have benefited from conservation and environmental initiatives which aim to restore and protect wetland habitat in the U.S. For example, the North American Waterfowl Management Plan was established in 1986 as an international plan to conserve waterfowl and migratory birds in North America (3) (9). Under the plan, over 4.5 billion U.S. dollars have been invested to help protect, restore and enhance more than 15.7 million acres of waterfowl habitat (9). Furthermore, the U.S. Department of Agriculture’s Conservation Reserve Program (CRP) has also converted more than 1.8 million hectares of cropland back to grassland in north-central America (3) (10). Both of these schemes will have benefited prairie and wetland nesting waterfowl, and it has been shown that breeding-pair abundance of the blue-winged teal is greater in areas of restored grassland than in areas of agricultural crop land (3). 

More research is needed into the breeding biology and wintering ecology of the blue-winged teal. An improved understanding of this species will help to determine how money can be more effectively spent to manage prairies and wetlands for the benefit of both the blue-winged teal and other waterfowl populations in these regions (3).

ARKive is supported by OTEP, a joint programme of funding from the UK FCO and DFID which provides support to address priority environmental issues in the Overseas Territories, and Defra

Find out more about the blue-winged teal and other bird species:

• BirdLife International:
  http://www.birdlife.org/datazone/speciesfactsheet.php?id=443
• Rohwer, F.C., Johnson, W.P. and Loos, E.R. (2002) Blue-winged teal (Anas discors). In: Poole, A. (Ed.) The Birds of North America Online. Cornell Lab of Ornithology, Ithaca. Available at:
  http://bna.birds.cornell.edu/bna/species/625