Species: Anas strepera
Gadwall
Species
Encyclopedia of Puget Sound
Classification
Kingdom
Animalia
Phylum
Craniata
Class
Aves
Order
Anseriformes
Family
Anatidae
Genus
Anas
NatureServe
Classification
Other Global Common Names
Pato Friso - canard chipeau
Informal Taxonomy
Animals, Vertebrates - Birds - Waterfowl
Formal Taxonomy
Animalia - Craniata - Aves - Anseriformes - Anatidae - Anas - Considered by some authors as two separate species, A. STREPERA (common gadwall) and A. COUESI (Coues' gadwall), the latter now extinct (AOU 1983). See Livezey (1991) for a phylogenetic analysis and classification (supergenera, subgenera, infragenera, etc.) of dabbling ducks based on comparative morphology, in which STREPERA is placed in the genus MARECA.
Ecology and Life History
Migration
true - true - true - Partially migratory. Migratory populations move northward in spring, departing wintering areas by March or early April, usually arriving at northernmost breeding grounds late April-early May; move southward September-October (sometimes later) (Ringelman 1990, Terres 1980). Primary migration corridor originates in the prairies and extends through the low plains region of the central and south-central U.S. and into Mexico; secondary migration routes link the prairies with the Pacific Northwest, northern and central California, and northern Utah; Utah breeders winter in central and southern California and Mexico; migrates also along diagonal routes from Great Plains to central and southern Atlantic coast (Ringelman 1990). Gadwalls banded in breeding areas in north-central Colorado were recovered primarily near the banding areas and in central and coastal Texas, northern Utah, along the east and west coast of Mexico, and in the Interior Highlands of Mexico (Szymczak and Rexstad 1991).
Non-migrant
true
Locally Migrant
true
Food Comments
Feeds on leaves, stems, and tubers of aquatic plants. Also eats algae and seeds of sedges and grasses. Occasionally grazes in pastures and grain fields; may feed on acorns. Eats some small fishes and aquatic invertebrates (e.g., insects, crustaceans). Aquatic invertebrates comprise about half the diet in spring and summer; eats green portions of aquatic plants in non-nesting season; feeds generally in water 15-66 cm deep (Ringelman 1990). Juveniles intitally eat equal amount of animal and plant food; plant food begins to dominate after 2 weeks (Ringelman 1990).
Reproduction Comments
Breeding usually begins in mid-April in the south to early June in the north. Clutch size: usually about 9-11. Incubation: about 4 weeks, by female. Young are tended by female, can fly at 49-63 days. Relatively high percentage of yearlings do not breed. Up to at least a few hundred nests/ha on islands lacking mammalian predators.
Ecology Comments
Molting males may form groups of hundreds or thousands in mid-summer. Annual survivorship of adults banded in Colorado was 69-75% (Szymczak and Rexstad 1991).
Length
51
Weight
990
Conservation Status
NatureServe Global Status Rank
G5
Global Status Last Reviewed
1996-11-21
Global Status Last Changed
1996-11-21
Other Status
LC - Least concern
Distribution
Conservation Status Map
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Global Range
H - >2,500,000 square km (greater than 1,000,000 square miles) - H - BREEDS: North America: southern Alaska, southern Yukon, southern Mackenzie (north to near Yellowknife; Can. Field-Nat. 106:254-256), northern Saskatchewan, central Manitoba, southern Ontario, southwestern Quebec, Prince Edward Island, Anticosti Island (rarely), and the New Brunswick-Nova Scotia border south locally to southern California, southern Nevada, northern Arizona, southern New Mexico, northern Texas, southern Kansas, Iowa, centralMinnesota, southern Wisconsin, northern Ohio, northern Pennsylvania (formerly), and, on the Atlantic coast, to North Carolina (one isolated breeding area in northern Alabama); also in the Old World (AOU 1983). Highest breeding densities occur in the northern Great Plains and intermountain valleys of the western U.S.; some portions of Alaskan, Pacific, and Atlantic coasts also have important breeding populations (Ringelman 1990). Range may be expanding eastward. WINTERS: North America: southern Alaska, southern British Columbia, Idaho, Colorado, southern South Dakota, Iowa, the southern Great Lakes, and Chesapeake Bay on the Atlantic coast (rarely from New Brunswick and Nova Scotia) south to northern Baja California, Oaxaca, the state of Mexico, Puebla, Veracruz, Tabasco, Yucatan, the Gulf Coast, Florida, the Bahamas, western Cuba, and (formerly) Jamaica; also in Old World (AOU 1983). Major wintering areas include coastal Louisiana and Texas, Gulf Coast of Mexico to Yucatan Peninsula, central and southern Atlantic coast of U.S., Central Valley of California, and much of the west coast of Mexico (Ringelman 1990); also northwestern Utah (Bear River refuge) and southeastern Missouri (Mingo refuge) (Root 1988). Formerly resident (COUESI group) in the northern Line Islands (Washington and New York islands); now extinct (AOU 1983).
Global Range Code
H
Global Range Description
>2,500,000 square km (greater than 1,000,000 square miles)