green-winged teal

green-winged teal
Name	Green-winged teal
Status	LC
Status system	IUCN3.1
Genus	Anas
Species	crecca
Authority	(Linnaeus, 1758)

green-winged teal is a small dabbling bird in the family Anatidae notable for its compact size and contrasting male plumage during the breeding season. It is widely distributed across North America, Eurasia, and parts of Africa, occurring in a variety of wetland habitats and migratory flyways. The species has long been studied by ornithologists associated with institutions such as the Smithsonian Institution, the Royal Society for the Protection of Birds, and the American Ornithological Society for its ecology, migration, and hybridization patterns.

Taxonomy and systematics

The species was formally described in 1758 by Carl Linnaeus in the tenth edition of Systema Naturae, placed in the genus Anas alongside other dabbling ducks. Subspecific and taxonomic treatment has involved debate among authorities including the International Ornithologists' Union, the American Ornithologists' Union, and the British Ornithologists' Union concerning separation of Eurasian and North American populations. Molecular studies published by researchers affiliated with universities such as Oxford University, University of Cambridge, and the University of California, Berkeley have used mitochondrial DNA and genomic markers to resolve relationships with congeners like the Eurasian teal and to assess introgression with species documented by the National Audubon Society and the Canadian Wildlife Service. Historical taxonomists including George Robert Gray and contemporary systematists at the Natural History Museum, London have contributed to nomenclatural stability.

Description

Adults display strong sexual dimorphism noted in field guides produced by the Cornell Lab of Ornithology, the Royal Society for the Protection of Birds, and the National Geographic Society. Breeding males show a chestnut head, a green lateral stripe through the eye, and a vertically oriented posterior wing patch that distinguishes them in identification keys used by the British Trust for Ornithology and the American Birding Association. Non-breeding males, females, and juveniles exhibit cryptic brown plumage similar to many species illustrated in works from the Audubon Society and the Linnean Society of London, requiring careful comparison with plates from the Field Museum of Natural History and measurements used by banding programs coordinated by the U.S. Geological Survey. Size and weight metrics are consistent with entries in encyclopedias such as the Encyclopaedia Britannica and checklists maintained by the IUCN.

Distribution and habitat

The species occupies breeding ranges across northern Canada, Alaska, northern Europe, and Siberia, with migratory wintering areas extending to the southern United States, Mexico, sub-Saharan Africa, and parts of southern Asia including China and Japan. Migration routes intersect major stopover sites managed by agencies like the U.S. Fish and Wildlife Service, Environment Agency (England), and conservation organizations such as Wetlands International. Habitats include shallow freshwater marshes, flooded grasslands, estuaries, and coastal lagoons documented in regional surveys by the Ramsar Convention and studies by the World Wildlife Fund. Distribution maps are regularly updated by collaborative programs involving the eBird platform, the British Trust for Ornithology atlases, and national surveys run by the Canadian Wildlife Service.

Behavior and ecology

Feeding behavior is characteristic of dabbling species described in treatises from the Royal Ontario Museum and observational studies by the Max Planck Institute for Ornithology. Diet consists primarily of seeds, aquatic invertebrates, and small crustaceans, with foraging tactics recorded at wetlands monitored by the Wildfowl & Wetlands Trust and the National Audubon Society. Social structure varies seasonally; flocks form on wintering grounds as documented in long-term census projects by the North American Waterfowl Management Plan partners and the Migratory Bird Treaty Act reporting frameworks. Predation and interspecific interactions involve raptors documented by the Raptor Research Foundation and larger waterfowl discussed in monographs from the Smithsonian Institution.

Reproduction and lifecycle

Breeding phenology follows patterns established in continental catalogs such as those of the American Ornithological Society and regional atlases from the British Trust for Ornithology. Nests are constructed on the ground amid vegetation in tundra and marsh habitats noted in field studies by researchers at the University of Alaska Fairbanks and the University of Cambridge. Clutch sizes, incubation periods, and fledging success metrics are reported in peer-reviewed journals published by the Ecological Society of America and data repositories managed by the Global Biodiversity Information Facility. Lifecycle stages include precocial ducklings that feed with parental guidance, a strategy compared in comparative analyses by the Royal Society and the Zoological Society of London.

Conservation and threats

Currently assessed as Least Concern by the IUCN Red List, the species nonetheless faces pressures documented in conservation plans from the North American Waterfowl Management Plan, the European Bird Census Council, and the African-Eurasian Migratory Waterbird Agreement. Threats include habitat loss from agricultural conversion recorded in reports by the Food and Agriculture Organization, wetland drainage cited by the Ramsar Convention, climate change impacts assessed by the Intergovernmental Panel on Climate Change, and hunting pressures regulated under legislation such as the Migratory Bird Treaty Act and national frameworks overseen by the U.S. Fish and Wildlife Service and the Department for Environment, Food & Rural Affairs. Conservation measures promoted by NGOs including the Wildfowl & Wetlands Trust, BirdLife International, and the National Audubon Society emphasize wetland protection, management of hunting quotas, and international cooperation through treaties like the Convention on Biological Diversity.

Category:Anas Category:Birds described in 1758