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Aix sponsawood duck

By Andrea Pope

Geographic Range

Aix sponsa is found on the east coast of North America from Nova Scotia in the north, to Florida and the Gulf of Mexico in the south, and west to the center of the United States. Birds in the eastern part of the range migrate southeast in the winter. Wood ducks are also found from British Columbia to the Mexican border on the west coast. They spend the winter in southern California and the Mexican Pacific coast. Wood ducks in the southern part of the range do not migrate. ("Wood Duck, Aix sponsa", 2000; "Wood Duck (Aix sponsa)", 1999)

Habitat

Wood ducks occupy a wide variety of habitats including woodland areas along lakes, rivers, creeks, beaver and farm ponds and various other freshwater vegetated wetland areas. Because wood ducks are cavity nesters, the availability of nesting sites within one mile of water is necessary. Winter habitats are the same as those used during breeding. (Hepp and Bellrose, 1995; "Wood Duck, Aix sponsa", 2000; "Wood Duck (Aix sponsa)", 1999)

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams

Physical Description

Wood ducks are small to medium sized birds. Both male and female adults have a crest on their head, a rectangular shaped tail, white bellies and white lines on the back of the wings. Males are 48 to 54 cm long, while females are 47 to 51 cm long. Their wingspans are 70 to 73 cm long and they weigh between 500 and 700 g. The sexes are dimorphic. The males' heads are iridescent green, blue and purple and have two white lines that are parallel and run from the base of the bill and behind the eye to the back of the head. Male wood ducks also have red eyes, red at the base of the bill, rust-colored chests, bronze sides and black backs and tails. The females are brownish to gray and have white eye rings, white throats and gray chests. Juvenile wood ducks resemble adult females. Wood ducks are sometimes mistaken for American widgeons (Anas americana) when flying because the white lines that wood ducks have at the back of their wings are not visible. Also female wood ducks are mistaken for female Mandarin ducks (Aix galericulata). The difference lies in the Mandarin duck's lighter gray head and less distinctive eye patch. (Hepp and Bellrose, 1995; "Wood Duck, Aix sponsa", 2000)

  • Sexual Dimorphism
  • male larger
  • sexes colored or patterned differently
  • male more colorful
  • Range mass
    635 to 681 g
    22.38 to 24.00 oz
  • Average mass
    600 g
    21.15 oz
  • Range length
    47 to 54 cm
    18.50 to 21.26 in
  • Range wingspan
    70 to 73 cm
    27.56 to 28.74 in
  • Average basal metabolic rate
    2.247 W
    AnAge

Reproduction

Aix sponsa shows courtship behaviors in the fall and again in the spring. Male wood ducks are serially monogamous (they stay with one female for one breeding season but mate with a different female the next year). Males use their colorful plumage to attract females. Females use a loud penetrating call to attract males. Wood ducks have several courtship displays, such as the wing-and-tail-flash and mutual preening. During the wing-and-tail-flash male wood ducks raise their wings and tails rapidly, showing their broadsides to the female. Mutual preening involves both sexes nibbling at the head and neck of their mate. After mating, the males migrate to a separate location to molt. (Ehrlich, et al., 1988; Hepp and Bellrose, 1995)

Aix sponsa breeds in February and early March in the south and mid-March to mid April in the northern areas. In southern areas it is common for wood ducks to produce two broods in one breeding season. Copulation occurs in the water, the male mounts the female from behind and grabs her nape with his bill. Nests are built in cavities and are lined with wood chips and down. Females lay 6 to 15 eggs. It is not uncommon for a nest to have more than 15 eggs because at times other females will lay their eggs in the nests (a behavior called egg-dumping). Eggs are incubated for about 30 days and the chicks leave the nest within 24 hours of hatching. Chicks reach independence in 56 to 70 days and reach sexual maturity in one year. (Ehrlich, et al., 1988; Hepp and Bellrose, 1995; "Wood Duck, Aix sponsa", 2000)

  • Breeding interval
    In southern areas it is common for wood ducks to produce two broods in one breeding season.
  • Breeding season
    Breeding occurs in February and early March in the south and mid-March to mid April in the northern areas.
  • Range eggs per season
    6 to 15
  • Average eggs per season
    12
    AnAge
  • Average time to hatching
    30 days
  • Average time to hatching
    31 days
    AnAge
  • Range time to independence
    56 to 70 days
  • Average age at sexual or reproductive maturity (female)
    1 years
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    365 days
    AnAge
  • Average age at sexual or reproductive maturity (male)
    1 years
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    365 days
    AnAge

Female wood ducks incubate their eggs for approximately 30 days. Ducklings hatch 6 to 18 hours after the first crack appears in their shells. They are precocial and leave the nest within 24 hours of hatching (the mother calls the ducklings out of the nest). The female makes sure that there are no predators in the area before the ducklings leave the nest. Once out of the nest, the ducklings scatter in search of food. The chicks become independent from their mothers after 56 to 70 days of care. Males do not care for the young. (Hepp and Bellrose, 1995; "Wood Duck, Aix sponsa", 2000)

  • Parental Investment
  • no parental involvement
  • precocial
  • pre-hatching/birth
    • protecting
      • female
  • pre-weaning/fledging
    • protecting
      • female
  • pre-independence
    • protecting
      • female

Lifespan/Longevity

The average lifespan of A. sponsa is three or four years. The maximum recorded lifespan in the wild is roughly 15 years. Within the first two weeks after hatching 86 to 90% of the chicks die. One cause of mortality is predation. Hunting also accounts for some mortality, however, hunting pressures are not enough to endanger the species. ("Wood Duck", 2002; Hepp and Bellrose, 1995)

Behavior

Aix sponsa moves around by walking, flying and swimming. Wood ducks are diurnal and with the exception of females with ducklings, they sleep on the water. They are social animals and often congregate in the evening and migrate in pairs or small flocks. Although they are not territorial, their defense mechanisms to protect mates include chasing, pecking and hitting. Battles are often short. To threaten another bird, they jerk and jab their beaks. It is assumed that males are dominant over females, and adults are dominant over young birds. (Hepp and Bellrose, 1995; "Wood Duck, Aix sponsa", 2000; "Wood Duck (Aix sponsa)", 1999)

Home Range

We do not have information on home range for this species at this time.

Communication and Perception

Adult wood ducks have 12 calls, ducklings have 5. Most adult calls are used as warning calls and to attract mates. Both males and females have pre-flight calls. Females have calls that they use to locate their mate and to call their ducklings. Ducklings, who produce calls 2 to 3 days after hatching, have alarm, contact and threatening calls. By three months of age ducklings begin making some adult calls.

Wood ducks also have several courtship displays, such as the wing-and-tail-flash and mutual preening. In addition, they will display during agonistic interactions. (Hepp and Bellrose, 1995)

Food Habits

Wood ducks are omnivores. They feed on nuts, fruits, aquatic plants and seeds, aquatic insects and other invertebrates. The majority of their food includes acorns, hickory nuts, maple seeds, smart weeds, Diptera (true flies), Lepidoptera (butterflies and moths), Hemiptera (true bugs), Coleoptera (beetles), Isopoda (pillbugs and sowbugs), Decapoda (shrimp, crabs, and relatives), Trichoptera (caddisflies), Hymenoptera (wasps, bees, and ants), Odonata (dragonflies and damselflies), and Gastropoda (gastropods, slugs, snails). (Ehrlich, et al., 1988; Hepp and Bellrose, 1995; "Wood Duck (Aix sponsa)", 1999)

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods
  • mollusks
  • Plant Foods
  • seeds, grains, and nuts
  • fruit

Predation

The most common predators of A.sponsa are great horned owls (Bubo virginianus), mink (Genus Mustela), raccoons (Procyon lotor), red foxes (Vulpes vulpes), gray foxes (Urocyon cinereoargenteus), alligators (Alligator mississippiensis) and black rat snakes (Pantherophis obsoletus). Female wood ducks have an alarm call that alerts the ducklings of the presence of a predator. The ducklings will search for cover in the water while the mother swims away from them or feigns a broken wing to protect them.

Within the first two weeks of hatching, 86 to 90 percent of the chicks die. A main cause of mortality is predation. (Hepp and Bellrose, 1995)

Ecosystem Roles

Wood ducks sometimes occupy hooded merganser (Lophodytes cucullatus) nests and when hooded merganser eggs are left in the nests, wood ducks incubate the merganser eggs as well as their own. This occurs more frequently early in the season. Wood ducks are also important prey for their predators and act as predators themselves. (Hepp and Bellrose, 1995)

Economic Importance for Humans: Positive

Humans hunt A. sponsa and eat their meat and eggs. Because they have such colorful plumage, their feathers are sometimes used to make artificial lures for fishing. Wood ducks are also sought out by many bird watchers. (Ehrlich, et al., 1988; Ray, 2002)

  • Positive Impacts
  • food
  • body parts are source of valuable material
  • ecotourism

Economic Importance for Humans: Negative

There are no known adverse affects of A. sponsa on humans.

Conservation Status

As a result of hunting and habitat destruction A. sponsa was near extinction in the early nineteen hundreds. Today, despite the fact that they are hunted, their population is thriving. Hunting laws have been put into place to protect them and man-made nest boxes are being created to counter their loss of habitat. Man-made nests are placed at least 600 feet apart in secluded areas where nests would occur naturally. They are made of wood, leaves and other material.

Wood ducks are protected by the US Migratory Bird Treaty Act. ("Wood Duck", 2002; Ehrlich, et al., 1988; Ray, 2002)

Contributors

Alaine Camfield (editor), Animal Diversity Web.

Andrea Pope (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.

Glossary

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

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

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.

chemical

uses smells or other chemicals to communicate

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

ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates

ecotourism

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.

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.

fertilization

union of egg and spermatozoan

food

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

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

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.

omnivore

an animal that mainly eats all kinds of things, including plants and animals

oviparous

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

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

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).

terrestrial

Living on the ground.

visual

uses sight to communicate

young precocial

young are relatively well-developed when born

References

U.S. Department of Agriculture, Natural Resources Conservation Service, Madison, MS, and Wildlife Habitat Council. 1999. "Wood Duck (Aix sponsa)" (On-line). Northern Prairie Wildlife Research Center. Accessed March 29, 2004 at http://www.npwrc.usgs.gov/resource/1999/woodduck/woodduck.htm.

The Georgia Museum of Natural History and Georgia Department of Natural Resources. 2000. "Wood Duck, Aix sponsa" (On-line). Accessed March 29, 2003 at http://museum.nhm.uga.edu/gawildlife/birds/anseriformes/asponsa.html.

Alabama Game and Fish Division. 2002. "Wood Duck" (On-line). Private Forest Management Team. Accessed March 29, 2004 at http://www.pfmt.org/wildlife/somethings/wood_duck.htm.

Ehrlich, P., D. Dobkin, D. Wheye. 1988. The Birder's Handbook: A Field Guide to the Natural History of North American Birds. New York: Simon and Schuster.

Hepp, G., F. Bellrose. 1995. The Birds of North America. Philadelphia, PA: The American Ornithologist' Union and The Academy of Natural Sciences.

Ray, L. 2002. "Species: Aix sponsa, The North American Wood Duck" (On-line). Accessed March 18, 2003 at http://richland.uwc.edu/Dept/Biology/accounts/woodduck.htm.

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