Anas discors

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.

• Biogeographic Regions
• nearctic nearctic
  • native native
• neotropical neotropical
  • native native
• australian australian

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.

• Habitat Regions
• temperate temperate
• freshwater freshwater

• Aquatic Biomes
• lakes and ponds
• temporary pools

• Wetlands
• marsh marsh
• swamp swamp

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.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• female larger
• male more colorful

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.

• Mating System
• monogamous monogamous

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.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• oviparous oviparous

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.

• Parental Investment
• precocial 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.

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.

• Key Behaviors
• terricolous
• flies
• natatorial natatorial
• diurnal diurnal
• motile motile
• migratory migratory
• social social

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.

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.

• Communication Channels
• visual visual
• acoustic acoustic

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

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.

• Primary Diet
• carnivore carnivore
  • insectivore insectivore
  • eats non-insect arthropods
  • molluscivore molluscivore
• herbivore herbivore
  • folivore folivore

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

• Plant Foods
• leaves
• seeds, grains, and nuts
• algae
• phytoplankton phytoplankton

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 ( Mustela 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 ).

• Anti-predator Adaptations
• cryptic 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 .

Economic Importance for Humans: Positive

Blue-winged teal are game birds.

• Positive Impacts
• food 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.

• 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.

Additional Links

Encyclopedia of Life

BioKIDS Critter Catalog

Contributors

Tanya Dewey (editor), Animal Diversity Web.

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

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

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

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.