Aix sponsa
wood duck

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)

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)

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)

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)

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)

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)

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)

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

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)

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)

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)

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)

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)

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

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)