Anas platyrhynchus Linnaeus, 1758, Europe. Seven subspecies.
OTHER COMMON NAMES
English: Greenhead, koloa; French: Canard colvert; German: Stockente; Spanish: Anade Azulуn.
19.7–25.6 in (50–65 cm); 1.7–3.5 lb (750–1,580 g). Green head, brown chest, blue speculum.
A. p. platyrhynchus: widespread throughout the nearctic, in palearctic from Iceland to Kamchatka and south to the Mediterrean; winters on most of Pacific coast from the Aleu- tians to California, southern half of the United States, northeastern Mexico, the West Indies, northern Africa, and from Iraq west to southeastern China. A. p. conboschas: coasts of southern Greenland. A. p. fulvigula: coastal Alabama west to Florida peninsula. A. p. maculosa: Gulf coast from Mississippi south to central Tamaulipas, Mexico; winters south to Veracruz. A. p. diazi: southeastern Arizona to western Texas and south to Mexico. A. p. wyvilliana: Kauai, Oahu, and Hawaii, Hawaiian Islands. A. p. laysanensis: Laysan Island, Hawaiian Islands. Populations elsewhere are introduced.
Shallow and calm waters of all types of natural or artificial wetlands and saltwater and brackish water. Prefers some vegetative cover.
Territorial to midincubation. Males then abandon their mates and territory. The c. 39.54–274.29 acres (16–111 ha) large, overlapping territories are defended aggressively. Forced copulations occur. Typical
s are the grunt-whistle and headup- tail-up displays used in courtship. Migratory.
FEEDING ECOLOGY AND DIET
Feeds on water by dabbling, head-dipping, upending, and rarely diving, and on land forages by grazing and probing. Omnivorous diet includes terrestrial and aquatic invertebrates, fish, amphibians, and various plant parts.
Seasonally monogamous. Breeding begins Feb.–Jun., depending on locality. The nest is made in a cavity or the ground. Generally lays 9–13 eggs; incubation c. 27–28 days; fledging 50–60 days. Becomes sexually mature at 1 year.
Common. Only Hawaiian subspecies are rare. A. p. laysanensis considered Vulnerable and listed on Appendix I of CITES. A. p. wyvilliana considered Critically Endangered. The other subspecies are common. A. p. diazi may be threatened by hybridization with southward spreading A. p. platyrhynchus.
SIGNIFICANCE TO HUMANS
Hunted for sport.
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