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Anas discorsblue-winged teal

By Monica Mingo

Geographic Range

During the summer months, blue-winged teal can be found throughout North America, from southeastern Alaska (western limit) to the Atlantic coast (eastern limit). They are also found in the continental U.S. in the Great Plains as far south as the Gulf Coast of Texas and Louisiana. In the winter months they migrate southwards to the Carolinas, southern California, and New Mexico and into tropical South America. Although Anas discors is commonly found in Neartic regions, it is also found in Australia. These ducks breed in southern Alaska and western Canada and south to northwestern California, New Mexico, and New York. (Lemaster, 1985)

Habitat

Freshwater habitats for Anas discors include shallow ponds and seasonal and permanent wetlands. They often use both temporary and permanent ponds. During breeding season, blue-winged teal remain near the water's edge in ponds and wetlands, preferring to breed in areas of calm, sluggish water. (Bennett, 1938)

  • Aquatic Biomes
  • lakes and ponds
  • temporary pools

Physical Description

Anas discors are called blue-winged teal because both sexes have blue spots on their forewings. They also have large white patches on the front of the wing, best visible when in flight. Males are smaller than females. Males have a large vertical white crescent on their face, between the eye and the bill, and a white patch on their rear flank. Females lack the crescent and white patch, with dull gray-brown coloration.

Wingspans range from 56 to 62 cm, and total lengths are typically 36 to 41 cm. Adults weigh 280 to 499 g. (Guillemain, et al., 2007)

  • Sexual Dimorphism
  • female larger
  • male more colorful
  • Range mass
    280 to 499 g
    9.87 to 17.59 oz
  • Range length
    36 to 41 cm
    14.17 to 16.14 in
  • Range wingspan
    56 to 62 cm
    22.05 to 24.41 in

Reproduction

Blue-winged teal are seasonally monogamous. Pairs usually form on wintering grounds and during spring migration. Most female are paired when they arrive on breeding grounds.

A group of males will court one female. Males swim after females and perform a variety of courtship displays. Usually, courtship begins in flight, when males call and pursue females in an erratic flight. A typical on-water display would be: a male swims in front of a female and with his body at an angle to her line of her movement, but his head is up so that the bill points away from the female. The female accepts a male by stretching her head outward. Then her head is lowered and her bill is pointed toward the male. They both perform a head pump. (Bailey, et al., 1973; Rohwer, et al., 2002)

Blue-winged teal nest from late April through early May. They tend to breed in northern prairie potholes and parklands. Nesting habitat includes wetland areas within grasslands, such as shallow marshes, sloughs, flooded ditches, and temporary ponds. Females lay 6 to 14 eggs, which take 21 to 40 days to hatch. Young reach the fledgling stage at about 24 days and are independent after 40 days. (Livezey, 1980)

  • Breeding interval
    Blue-winged teal breed once yearly.
  • Breeding season
    Blue-winged teal mate from late spring to early summer.
  • Range eggs per season
    6 to 14
  • Range time to hatching
    21 to 40 days
  • Range fledging age
    24 to 25 days
  • Range time to independence
    40 (low) days

Females are in charge of nest maintenance and rearing the young, males play no apparent part. Females change their breeding locality each year. To create a nest, a female digs a bowl-shaped depression with her feet and pulls in dried grass that is available around the nest bowl. She lays one egg per day, typically totalling more than 10 eggs. Upon returning to the nest, she lands a short distance from the nest so that predators do not know the nest location. When the eggs hatch the female preens her hatchlings until they are dry and clean. She then leads her ducklings to a nearby wetland and does not return to the nest. The young remain with their mother until they are ready to fly, about 40 days post-hatching. (Glover, 1986; Kear, 2005; Livezey, 1980)

  • Parental Investment
  • precocial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • provisioning
      • female
    • protecting
      • female

Lifespan/Longevity

Ducklings are susceptible to parasites and diseases, and often do not reach maturity. Botulism (Clostridium botulinum) and avian cholera (Pasteurella multocida), both bacterial diseases, impact blue-winged teal populations heavily through ingestion of the bacteria. Migration is another source of mortality, particularly in young teal. Blue-winged teal that do survive to adulthood have been known to live up to 17 years. (Rohwer, et al., 2002; Rohwer, et al., 2002)

  • Range lifespan
    Status: wild
    17.4 (high) years
  • Typical lifespan
    Status: wild
    17.4 (high) years

Behavior

Blue-winged teal are highly gregarious, tending to move in or form a group with others of the same species. The only time they are not social is during breeding season. Blue-winged teal migrate between wintering and breeding ranges each year. They are generally subordinate to larger-bodied dabbling and diving ducks. They are active during the day. Blue-winged teal can walk well on land and in shallow water. They are not known for climbing, but they often rest and preen on logs and rocks that are slightly above water. They can gain flight directly from land or water. The only time a blue-wing teal will dive in the water is if threatened by a predator or when trying to escape copulation attempts. Blue-winged teal use preening, head-scratching, and stretching of the body to self-clean. (Rohwer, et al., 2002)

Home Range

Blue-winged teal establish small territories around nests during the breeding season. During the remainder of the year they do not defend territories or remain within a set home range. (Rohwer, et al., 2002)

Communication and Perception

Males that are unpaired usually make a loud, high-pitched whistle "peew" or a low-pitched nasal "paay." A male's decrescendo begins with a single call that is followed by a short series of low-pitched "pews." These types of calls are broadcast during fall and early winter, but rarely after pair formation.

During the mating season, females give a short series of loud, evenly- spaced, single quacks, which vary in volume and duration. When a female that has already found a mate is being pursued by another male, she makes a quack sound followed by a "gaek" note to warm them off. Females also quack to communicate with their young. (Rohwer, et al., 2002)

Food Habits

Blue-winged teal consume a variety of aquatic invertebrates, including insects, crustaceans, snails, and small clams, and aquatic vegetation, including seeds. When females are breeding they require a diet higher in protein, so they eat more invertebrates and seeds. (Rohwer, 1986)

  • Animal Foods
  • insects
  • mollusks
  • aquatic crustaceans
  • other marine invertebrates

Predation

Long-tailed weasels Mustela frenata often consume blue-wing teal eggs. Females are susceptible to predation by raptors when incubating and when walking near nests between incubation bouts. In prairies, these ducks are captured by red foxes Vulpes vulpes. Females and ducklings are cryptically colored to avoid detection by prey.

Other predators include: peregrine falcons (Falco peregrinus), minks (Neovison vison), raccons (Procyon lotor), bald eagles (Haliaeetus leucocephalus), great horned owls (Bubo virginianus), red-tailed hawks (Buteo jamaicensis), coyotes (Canis latrans), striped skunks (Mephitis mephitis), American badgers (Taxidea taxus), American crows (Corvus brachyrhynchos), black-billed magpies (Pica hudsonia), and Franklin's ground squirrels (Spermophilus franklinii). (Rohwer, et al., 2002)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Most blue-winged teal live mutualistically with other dabbling ducks. There are many parasites that infect this species, including Pasteurella multocida (avian cholera), and protozoans, such as Cyanthocotyle bushiensis and Spahaeridotreme globulus. (Rohwer, et al., 2002)

Mutualist Species
  • other dabbling ducks (Anas)
Commensal/Parasitic Species
  • Avian cholera (Pasteurella multocida)
  • protozoans (Cyanthocotyle bushiensis)
  • protozoans (Spahaeridotreme globulus)

Economic Importance for Humans: Positive

Blue-winged teal are game birds. (Rohwer, et al., 2002)

  • Positive Impacts
  • food

Economic Importance for Humans: Negative

One concern about blue-winged teals is the spread of avian influenza, which can decimate bird populations and be transmitted to humans. (Rohwer, et al., 2002)

  • Negative Impacts
  • injures humans
    • carries human disease

Conservation Status

Blue-winged teal, although not rare, are protected under the Migratory Bird Act. Bag limits are set to maintain healthy populations. Also, the U.S. and Canada have banned pesticides and other contaminants that had been killing blue-winged teals. For instance, mercury levels and also organochlorine residue found in lakes and ponds are controlled/limited by these governments. Dieldrin is a type of insecticide that can concentrate in migratory birds--it has since been banned.

Humans often negatively affect Anas discors. Human littering can cause suffocation in this bird--from consuming or getting stuck in plastic trash and fishing lines. Also, blue-winged teal can collide with power lines, fences, and barbed wire in flight, or with vehicles. However, the most important negative influence is habitat degradation and loss due to human activities, especially wetland draining and conversion to agriculture. (Rohwer, et al., 2002; Rohwer, et al., 2002)

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Monica Mingo (author), Radford University, Karen Powers (editor, instructor), Radford University.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

diurnal
  1. active during the day, 2. lasting for one day.
endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

folivore

an animal that mainly eats leaves.

food

A substance that provides both nutrients and energy to a living thing.

freshwater

mainly lives in water that is not salty.

herbivore

An animal that eats mainly plants or parts of plants.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

marsh

marshes are wetland areas often dominated by grasses and reeds.

migratory

makes seasonal movements between breeding and wintering grounds

molluscivore

eats mollusks, members of Phylum Mollusca

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

phytoplankton

photosynthetic or plant constituent of plankton; mainly unicellular algae. (Compare to zooplankton.)

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

swamp

a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

visual

uses sight to communicate

young precocial

young are relatively well-developed when born

References

Bailey, R., N. Seymour, G. Stewart. 1973. Rape behavior in blue-winged teal. Auk, 95: 188-190.

Bennett, L. 1938. The blue-winged teal: its ecology and management. Boston: Collegiate Press.

Botero, J. 1994. Foods of Blue-Winged Teal in Two Neotropical Wetlands. Wildlife Ecology, 12: 561-565.

Connelly, J., I. Ball. 1984. Comparisons of aspects of breeding blue-winged and cinnamon teal in eastern Washington. Wilson Bulletin, 96/4: 626-633.

Glover, F. 1986. Nesting and Production of the Blue-Winged Teal (Anas discors Linnaeus) in Northwest Iowa. The Journal of Wildlife Management, 20: 28-46.

Guillemain, M., C. Arzel, P. Legagneux, H. Fritz. 2007. Predation risk constrains the plasticity of foraging behaviour in teals, Anas crecca: a flyway-level circumannual approach. Animal Behavior, 73/5: 845-854.

Kear, J. 2005. Ducks, Goose and Swans. United Kingdom: Oxford University Press.

Lemaster, R. 1985. The Great Gallery of Ducks and Other Waterfowl. Mechanicburg, PA: Stackpole Books.

Livezey, B. 1980. Effects of selected observers-related factors on fates of ducks nests. Journal of Wildlife Management, 8: 123-128.

Rohwer, F. 1986. Composition of Blue Winged Teal Eggs in Relation to eggs size, Clutch Timing of Laying. The Condor, 88: 513-519.

Rohwer, F., W. Johnson, E. Loos. 2002. Blue-winged teal. The Birds of North American, 625: 1-35.

Smith, R., L. Flake. 1985. Movement and Habitat of Brood-rearing Wood Ducks on a Praire River. Journal of Wildlife Management, 42/9: 437-442.

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