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Overview

Brief Summary

Gadwalls are often very busy under water, with only their tail sticking out of the water. They look for food on the bottom. Gadwalls are one size smaller than mallard ducks. They are only seen in nature areas, whereas mallards are seen everywhere, particularly city parks.
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Anas strepera

While many ducks in North America are adorned with bright blues, greens, or reds, the Gadwall’s coloration is far more subdued. The male is gray overall with a tan head and gray bill, while the female is brownish overall with a dull yellow bill. Besides their medium size (19-23 inches) and nondescript plumage, Gadwalls may be identified in flight by a small white patch on the trailing edge of their wings. Gadwalls are found widely across the Northern Hemisphere. In North America, Gadwalls breed primarily in the northern Great Plains. Smaller breeding areas can be found in the Rocky Mountains, in Alaska, in coastal California, and along the Great Lakes. Many Gadwall populations in the Rockies are non-migratory, but the majority of Gadwalls migrate south for the winter, when they may be found along the Atlantic and Gulf coasts of the southeast, the southern Plains, the Pacific coast from northern California north to Washington, and in southern portions of the Great Lakes. In Eurasia, Gadwalls breed in northern and central Europe, wintering from central Europe south to North Africa. In summer, the Gadwall breeds primarily in wetlands surrounded by grasslands or prairie. In winter, Gadwalls frequent small ponds as well as freshwater and saltwater marshes. Gadwalls feed on aquatic plants, seeds, and invertebrates in the water column. Gadwalls may be seen either on land or in the water, where they may be observed foraging for food. This species may also be observed taking off straight up from the water or undertaking straight, swift flights on migration or between breeding or foraging grounds. Gadwalls are most active during the day.

Threat Status: Least concern

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Comprehensive Description

Description of Anas strepera

Het vrouwtje is geliger van kleur dan het mannetje.
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1geron

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Distribution

Anas strepera is a migratory bird. It winters from southern Mexico and Guatemala to coastal Alaska, the Atlantic, and Gulf coast regions of the United States and many areas in-between. Their summer breeding grounds range from the Atlantic coast of Canada to as far north as the western coastal regions of Alaska. Although, the largest concentration of them are found in the summer breeding grounds of the prairie pot-hole region of southern Canada and northern United States. Gadwalls can also be found in Iceland during the breeding season. They can also be found breeding in the Iceland, British Isles, Europe, and Asia (Tesky 1993, LeSchack et. al. 1997).

Biogeographic Regions: nearctic (Native ); palearctic (Native ); oriental (Native )

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Range Description

Anas strepera has an extremely wide distribution across the Palearctic and Nearctic regions, occurring in the U.S.A., Canada, Mexico, Guatemala, Belize, Cuba, Jamaica, Iceland, Ireland, the United Kingdom, Portugal, Spain, Morocco, Western Sahara, Andorra, France, Monaco, Belgium, Luxembourg, the Netherlands, Switzerland, Liechtenstein, Austria, Italy, Germany, Denmark, the Czech Republic, Slovenia, Croatia, Bosnia and Herzegovina, Serbia, Montenegro, Kosovo, Albania, The Former Yugoslav Republic of Macedonia, Greece, Bulgaria, Romania, Hungary, Slovakia, Moldova, Ukraine, Belarus, Russia, Turkey, Tunisia, Libya, Egypt, Sudan, Ethiopia, Georgia, Armenia, Azerbaijan, Syria, Israel, Lebanon, Jordan, Iraq, Saudi Arabia, Iran, Turkmenistan, Uzbekistan, Tajikistan, Kyrgyzstan, China, Mongolia, Pakistan, India, Nepal, Bangladesh, Bhutan, Burma and Japan. The subspecies couesi was discovered on Teraina, Kiribati in 1874, but it has not been seen since and is now extinct (del Hoyo et al. 1992).
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occurs (regularly, as a native taxon) in multiple nations

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National Distribution

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

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Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) 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).

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North America; Oceania; Scotian Shelf to the Gulf of Mexico
  • North-West Atlantic Ocean species (NWARMS)
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In North America the gadwall's breeding range extends from southern
Alaska and southern Yukon to the New Brunswick-Nova Scotia border, south
locally to southern California, northern Texas, central Minnesota, and
northern Pennsylvania, and along the Atlantic Coast south to Florida and
the Gulf Coast [6,19].  It also breeds in Iceland, the British Isles,
Europe, and Asia [6].

In North America the gadwall winters from coastal Alaska south to
southern Mexico, the Gulf Coast, and along the Atlantic Coast to
southern New England [6,19].
  • 19.  DeGraaf, Richard M.; Scott, Virgil E.; Hamre, R. H.; [and others]
  • 6.  Johnsgard, Paul A. 1979. A guide to North American waterfowl.        Bloomington, IN: Indiana University Press. 274 p.  [20026]

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Regional Distribution in the Western United States

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This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):

    1  Northern Pacific Border
    2  Cascade Mountains
    3  Southern Pacific Border
    4  Sierra Mountains
    5  Columbia Plateau
    6  Upper Basin and Range
    7  Lower Basin and Range
    8  Northern Rocky Mountains
    9  Middle Rocky Mountains
   10  Wyoming Basin
   11  Southern Rocky Mountains
   12  Colorado Plateau
   13  Rocky Mountain Piedmont
   14  Great Plains
   15  Black Hills Uplift
   16  Upper Missouri Basin and Broken Lands

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Occurrence in North America





AL AK AZ AR CA CO CT DE FL GA
ID IA KS LA ME MD MA MI MN MS
MO MT NE NV NJ NM NY ND OH OK
OR PA RI SC SD TN TX UT VT VA
WA WV WI WY


AB BC MB SK



MEXICO

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Physical Description

Morphology

Gadwalls can be very easy to identify in hand, but they can be very difficult to identify in the field. They are a medium-sized dabbling duck with non-distinct plumage and are most commonly misidentified in the field. The male and female gadwalls look very similar and resemble the hen mallard in drab plumage. The adult male has a gray plumage in the breeding season with distinct vermiculation on the scapular and back feathers. The head is brown and the upper and lower tail covers are black. The adult male tertials are long, and acutely pointed colored silver-gray. In basic plumage, the male Gadwall looks almost identical to the female. The adult female tertials are shorter and more bluntly pointed. The females lack the vermiculation but look very similar to the males with plumage more is more brownish on the back and buffy tan on the breast. The most distinguishing marks for both male and females are the white secondaries with black greater secondary coverts. This is very easy to see when in flight. The white speculum is the most identifying mark to recognize both sexes in the field but is only visible when in flight. The males will begin their prebasic molt after breeding with the female sometime during early to mid-summer depending on mating time and nest success. During this time they are not able to fly and are very vulnerable to predation (Bellrose 1980, Tesky 1993, LeSchack et al. 1997).

The Gadwall has to go through its juvenile plumage that may last 10 weeks until they begin their prealternate molt. The juvenile plumage of both the male and females look almost identical to the female plumage of all dabbling ducks. When the male juvenile goes through its prealternate molt, it then begins to take on the distinct male plumage with silver tipped tertials, puffy gray head, vermiculation, and rusty colored speculum (Bellrose 1980, LeSchack et al. 1997).

Range mass: 500 to 1044 g.

Average mass: 860 g.

Range length: 46 to 57 cm.

Average length: 50 cm.

Other Physical Features: endothermic ; bilateral symmetry

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Size

Length: 51 cm

Weight: 990 grams

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Ecology

Habitat

Gadwalls prefer marshes, sloughs, ponds, and small lakes with grasslands in both fresh and brackish water as breading habitats. They tend to be more abundant on small prairie marshes than in temporary water areas, deep marshes, and open water marshes. They generally avoid wetlands that are bordered by woodlands or thick vegetation. In the winter they prefer the brackish water marshes with abundant leafy aquatic vegetation. There are many winter populations that have made yearly migrations back to the same waterfowl refuges, reservoirs, beaver ponds, and sewage treatment plants (Johnsguard 1979, Tesky 1993, LeSchack et al. 1997).

Range elevation: 0 (low) m.

Habitat Regions: temperate ; freshwater

Terrestrial Biomes: tundra ; taiga

Wetlands: marsh

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Habitat and Ecology

Habitat and Ecology
Behaviour The species is strongly migratory in the north of its range (Kear 2005b) although breeding populations in temperate regions are largely sedentary (del Hoyo et al. 1992). Males leave the breeding grounds in early-July (one month before the females and young), migrating to key waters to undergo a flightless moulting period lasting for c.4 weeks, after which they continue to the wintering grounds (Scott and Rose 1996). The return migration occurs from March to April (Scott and Rose 1996), and although the timing of the breeding season varies geographically the species generally nests late in the year (e.g. May-July) (Kear 2005b). It breeds in single pairs or loose groups (del Hoyo et al. 1992) and is usually observed in small parties outside of the breeding season, with large concentrations sometimes forming on passage (Madge and Burn 1988) or during the moulting period (Kear 2005b) (Madge and Burn 1988). Habitat The species inhabits highly productive (del Hoyo et al. 1992, Kear 2005b) and eutrophic (Snow and Perrins 1998) freshwater marsh or lake habitats (del Hoyo et al. 1992, Kear 2005b) in open lowland grassland (Johnsgard 1978, Madge and Burn 1988), showing a preference for sheltered, shallow, standing or slow-flowing waters (Snow and Perrins 1998) with abundant emergent vegetation (Johnsgard 1978, del Hoyo et al. 1992, Snow and Perrins 1998, Kear 2005b) and grass-covered islands providing cover for nesting (Johnsgard 1978, del Hoyo et al. 1992, Snow and Perrins 1998). It may also be found on permanent, shallow, slightly alkaline marshes (Johnsgard 1978, del Hoyo et al. 1992), as well as on oxbow lakes, channels (Flint et al. 1984), reservoirs and gravel-pits (Kear 2005b). After hatching, females move their broods to deeper marshes or to the edges of large impoundments, sometimes more than 1 mile away from the nesting sites (Johnsgard 1978). Rarely (e.g. in the winter) (Madge and Burn 1988) the species occurs along sheltered coasts (del Hoyo et al. 1992, Scott and Rose 1996) at coastal marshes (North America) (Kear 2005b), estuaries (Flint et al. 1984, Madge and Burn 1988, Snow and Perrins 1998), deltas or lagoons (Snow and Perrins 1998). Diet The species is predominantly herbivorous (del Hoyo et al. 1992), its diet consisting of the seeds, leaves, roots and stems of aquatic plants (del Hoyo et al. 1992) (submerged and emergent) as well as grasses and stoneworts Chara spp. (Kear 2005b), occasionally also taking cereal grains on land (Brown et al. 1982, Snow and Perrins 1998). In addition, the species may take a small amount of animal matter during the winter (Africa), such as insects, molluscs, annelids, amphibians, amphibian spawn and small fish (Brown et al. 1982). Breeding site The nest is a well-hidden (Johnsgard 1978) hollow (Snow and Perrins 1998) in grass and leaves positioned on the ground in thick vegetation (del Hoyo et al. 1992) such as nettles Urtica spp. (Madge and Burn 1988), grass tussocks, thick bushes, rushes or tall grass (Brown et al. 1982). The species shows a preference for dense, dry herbaceous vegetation (Johnsgard 1978) and often nests far from water (Madge and Burn 1988, Kear 2005b). It may nest in dense concentrations on islands (Madge and Burn 1988, Kear 2005b) (neighbouring nests as close as 5 m apart) (Snow and Perrins 1998) although it is not a colonial species (Madge and Burn 1988, Kear 2005b). Management information The cyclical removal of adult fish from an artificial waterbody (gravel pit) in the UK (leaving small fish for piscivorous birds) resulted in an increase in the winter use of the habitat by the species as result of an increase in the growth of submerged aquatic macrophytes (Giles 1994). The removed fish (dead or alive) were sold to generate funds (Giles 1994).


Systems
  • Terrestrial
  • Freshwater
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Comments: Lakes, ponds, rivers, marshes. Prefers freshwater but may be found on any open water during migration and winter. Moderate- to large-sized wetland of a permanent or semipermanent nature, expanses of open water with submersed vegetation, and open undisturbed shorelines are important molting habitats (Ringelman 1990).

Nests in thick vegetation near freshwater lakes, ponds, or streams, including open brackish or alkaline waters. Nests usually in dry upland site under clump of shrubs or in herbaceous vegetation, average of 300 m from water. Tends to nest near semipermanent wetlands that are relatively resistant to drought (Ringelman 1990). Commonly uses man-made ponds. May nest on island, upland meadow or grassland. Suitable nesting islands should be 0.1-0.5 ha in size, elongate, and separated from mainland by at least 150 m of water that remains 0.9 m deep in nesting season (Ringelman 1990). Successful breeders usually return to nesting area used the previous year (Szymczak and Rexstad 1991). A diversity of wetland types is required for successful reproduction, so that brood-rearing habitat is near nesting habitat; females will move brood up to 1.9 km to brood habitat (Ringelman 1990).

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marshes, sloughs, ponds, and small lakes with grasslands in both fresh and brackish water
  • North-West Atlantic Ocean species (NWARMS)
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Cover Requirements

More info for the terms: cover, density

For escape cover, gadwalls prefer large areas of open water water rather
than with emergents [16].  Tall, dense vegetation provides good nesting
cover for gadwalls.  As the vegetative cover increases, the potential
for nest establishment and success increases.  Height and density of
vegetation is assumed to be more important than species composition.  In
a California study, most gadwall nests were in vegetation 13 to 36
inches (33-91 cm) tall that provided concealment on all sides and above.
No nests were found in herbaceous cover less than 6 inches (15 cm) tall.
Fifty-one percent of nests in North Dakota nesting fields were in
herbaceous cover from 12 to 24 inches (30-60 cm) tall, while 47 percent
were in cover less than 6 inches (15 cm) tall [16].
  • 16.  Sousa, Patrick J. 1985. Habitat suitability index models: gadwall        (breeding). Biological Report 82(10.100). Washington, DC: U.S.        Department of the Interior, Fish and Wildlife Service. 35 p.  [20031]

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Preferred Habitat

Gadwall pairs use wetlands for feeding, loafing, and courtship prior to
nesting [16].  They prefer prairie marshes, sloughs, ponds, or small
lakes in grasslands of both freshwater and brackish habitats.  They
generally avoid wetlands bordered by woodlands or thick brush,
preferring those bordered by dense, low herbaceous vegetation, or with
grassy islands [6,17,19].  Shallow semipermanent prairie marshes are
preferred over deeper marshes, lakes or temporary water areas [6,16].
Sixy one percent of 1,073 gadwall broods observed over a 20-year period
in North and South Dakota were in semipermanent wetlands [16].

Winter habitat - Gadwalls prefer to winter in freshwater, marshy
habitats and slightly brackish estuarine bays [6,19].

Nesting - Gadwalls nest on well-drained sites on islands in lakes,
upland meadows or pastures, alfalfa fields, or on prairies usually
within 150 feet (45 m) of water.  They prefer to nest in uplands rather
than over water [19] and generally select the tallest, densest,
herbaceous or shrubby vegetation available to nest in [16].
  • 16.  Sousa, Patrick J. 1985. Habitat suitability index models: gadwall        (breeding). Biological Report 82(10.100). Washington, DC: U.S.        Department of the Interior, Fish and Wildlife Service. 35 p.  [20031]
  • 17.  Springer, Paul F.; Stewart, Robert E. 1977. Gadwall nesting in Maryland.        Auk. 67: 234-235.  [20042]
  • 19.  DeGraaf, Richard M.; Scott, Virgil E.; Hamre, R. H.; [and others]
  • 6.  Johnsgard, Paul A. 1979. A guide to North American waterfowl.        Bloomington, IN: Indiana University Press. 274 p.  [20026]

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Associated Plant Communities

More info for the term: cover

During the breeding season, gadwalls often inhabit islands in wetland
communities with patches of dense western snowberry (Symphoricarpos
occidentalis), slim nettle (Urtica gracilis), Canada thistle (Cirsium
arvense), rose (Rosa spp.), and brome (Bromus spp.).  Additionally,
gadwalls commonly use areas dominated by cattail (Typha spp.), bulrush
(Scirpus spp.), sedge (Carex spp.), and common rivergrass (Scolochloa
festucacea) [8].  Gadwalls will also use upland cover types of cropland,
pasture and hayland, grassland, and mixed prairie and weed [8,9,16].

REFERENCES :
NO-ENTRY
  • 16.  Sousa, Patrick J. 1985. Habitat suitability index models: gadwall        (breeding). Biological Report 82(10.100). Washington, DC: U.S.        Department of the Interior, Fish and Wildlife Service. 35 p.  [20031]
  • 8.  Hines, J. E.; Mitchell, G. J. 1983. Gadwall nest-site selection and        nesting success. Journal of Wildlife Management. 47(4): 1063-1071.        [21351]
  • 9.  Dahlsten, D. L.. 1986. Control of invaders. In: Mooney, Harold A.;        Drake, James A., eds. Ecology of Biological Invasions of North America        and Hawaii. Ecological Studies 58. New York: Springer-Verlag: 275-302.        [16144]

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Habitat: Plant Associations

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This species is known to occur in association with the following plant community types (as classified by Küchler 1964):

   K047  Fescue - oatgrass
   K048  California steppe
   K049  Tule marshes
   K050  Fescue - wheatgrass
   K051  Wheatgrass - bluegrass
   K053  Grama - galleta steppe
   K054  Grama - tobosa prairie
   K056  Wheatgrass - needlegrass shrubsteppe
   K057  Galleta - three-awn shrubsteppe
   K058  Grama - tobosa shrubsteppe
   K063  Foothills prairie
   K064  Grama - needlegrass - wheatgrass
   K065  Grama - buffalograss
   K066  Wheatgrass - needlegrass
   K067  Wheatgrass - bluestem - needlegrass
   K068  Wheatgrass - grama - buffalograss
   K069  Bluestem - grama prairie
   K072  Sea oats prairie
   K073  Northern cordgrass prairie
   K074  Bluestem prairie
   K075  Nebraska Sandhills prairie
   K076  Blackland prairie
   K077  Bluestem - sacahuista prairie
   K078  Southern cordgrass prairie
   K079  Palmetto prairie
   K094  Conifer bog
   K098  Northern floodplain forest
   K100  Oak - hickory forest

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Habitat: Ecosystem

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This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):

FRES14 Oak-pine
FRES15 Oak-hickory
FRES17 Elm-ash-cottonwood
FRES18 Maple-beech-birch
FRES19 Aspen-birch
FRES36 Mountain grasslands
FRES37 Mountain meadows
FRES38 Plains grasslands
FRES39 Prairie
FRES41 Wet grasslands
FRES42 Annual grasslands

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Habitat: Cover Types

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This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):

    16  Aspen
    17  Pin cherry
    18  Paper birch
    63  Cottonwood
    88  Willow oak - water oak - diamondleaf oak
    89  Live oak
    95  Black willow
   203  Balsam poplar
   217  Aspen
   235  Cottonwood - willow
   252  Paper birch

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Depth range based on 114 specimens in 1 taxon.

Environmental ranges
  Depth range (m): 0 - 0
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

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Migration

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.

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).

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Trophic Strategy

Gadwalls main food sources are aquatic vegetation, aquatic invertebrates, and seeds. They are surface feeders feeding mostly on plant material growing close to the surface. They can also be found in fields feeding on grain or even in woodlands feeding on acorns. Their main diet of plant material includes leaves and stems of aquatic plants. Gadwalls will also supplement their plant diet with insects, crustaceans, amphibians, mollusks, and fish. Females will eat a protein and fat rich diet prior to mating. This provide them with extra resources for the egg laying and incubation periods. During this time, males eat more plant material than females (LeSchack et al. 1997).

Some of the plant material Gadwalls eat: pondweed (Potamogeton spp.), niad (Najas spp.), water milfoil (Myriophyllum spp.), algae (Cladophoraceae), smartweed (Polygonum spp.), bulrush (Scirpus spp.), spikerush (Eleocharis spp.), saltgrass (Distichlis spp.) and muskgrass (Chara spp.).

Animal Foods: amphibians; fish; insects; terrestrial non-insect arthropods; mollusks

Plant Foods: leaves; seeds, grains, and nuts; algae

Primary Diet: omnivore

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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).

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Food Habits

Gadwalls are almost exclusively surface feeders.  They tend to feed in
rather shallow marshes having abundant aquatic plant life growing close
to the surface [6].  They sometimes feed in stubble fields for grain or
in woods for acorns [19].  They mainly consume leaves and stems of
aquatic plants but also eat insects, mollusks, crustaceans, amphibians,
and fishes [9,16,19].  Aquatic plants commonly eaten by gadwalls include
pondweed (Potamogeton spp.), widgeongrass (Ruppia maritima), saltgrass
(Distichlis spp.), muskgrass (Chara spp.), eelgrass (Zostera marina),
spikerush (Eleocharis spp.), spiked watermilfoil (Myriophyllum spicatum)
and filamentous algae [9,16,19].  The two most prominent plants in the
diet of gadwall in South Carolina are fragrant flatsedge (Cyperus
odoratus) and Carolina redroot (Lachnanthes caroliniana).  Major animal
foods include crustaceans, especially those belonging to the order
Anostraca, and insects, especially adult and larval chironomids
(Chironamidae) [16].

Recently hatched gadwalls in Alberta initially fed on invertebrates but
were essentially herbiverous by 3 weeks of age.  Major animal foods of
ducklings included adult and larval chironamids, water boatman
(Cerixidae), beetles (Coleoptera), and cladocerans (Cladocera).
Important plants in the duckling's diets were pondweed, green algae
(Cladophoracea), duckweed (Lemna minor), and seeds of American
sloughgrass (Beckmannia syzigachne) [16].
  • 16.  Sousa, Patrick J. 1985. Habitat suitability index models: gadwall        (breeding). Biological Report 82(10.100). Washington, DC: U.S.        Department of the Interior, Fish and Wildlife Service. 35 p.  [20031]
  • 19.  DeGraaf, Richard M.; Scott, Virgil E.; Hamre, R. H.; [and others]
  • 6.  Johnsgard, Paul A. 1979. A guide to North American waterfowl.        Bloomington, IN: Indiana University Press. 274 p.  [20026]
  • 9.  Dahlsten, D. L.. 1986. Control of invaders. In: Mooney, Harold A.;        Drake, James A., eds. Ecology of Biological Invasions of North America        and Hawaii. Ecological Studies 58. New York: Springer-Verlag: 275-302.        [16144]

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Associations

The Gadwall has many predators, including: humans from hunting and urban accidents, fox (Vulpes spp.), raccoons (Procyon lotor), coyotes (Canis latrans), badgers (Taxidea taxus), weasels (Mustela spp.), hawks (Accipitridae), crows (Corvus spp.), and minks (Neovison vison). (Tesky 1993).

Gadwalls are most vulnerable when females are nesting and when the males are molting from alternate to basic back to alternate plumage. Their main source of defense is to be on the water. Like all ducks, they also become very vulnerable when feeding to close to the shore in dense vegetation. This makes them subject to the quick strike of fox and coyotes (Tesky 1993, LeSchack et al. 1997).

Known Predators:

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Predators

Predators of gadwalls include humans, foxes (Vulpes spp.), raccoons
(Procyon lotor), striped skunks (Mephitis mephitis), coyotes (Canis
latrans), badgers (Taxidea taxus), weasels (Mustela spp.), minks
(Mustela vison), crows (Corvus spp.), and magpies (Pica spp.)
[8,9,12,14].
  • 12.  Martz, Gerald F. 1967. Effects of nesting cover removal on breeding        puddle ducks. Journal of Wildlife Management. 31(2): 236-247.  [16284]
  • 14.  Sargeant, Alan B.; Allen, Stephen H.; Eberhardt, Robert T. 1984. Red fox        predation on breeding ducks in midcontinent North America. Wildlife        Monographs No. 89. Washington, DC: The Wildlife Society. 41 p.  [18149]
  • 8.  Hines, J. E.; Mitchell, G. J. 1983. Gadwall nest-site selection and        nesting success. Journal of Wildlife Management. 47(4): 1063-1071.        [21351]
  • 9.  Dahlsten, D. L.. 1986. Control of invaders. In: Mooney, Harold A.;        Drake, James A., eds. Ecology of Biological Invasions of North America        and Hawaii. Ecological Studies 58. New York: Springer-Verlag: 275-302.        [16144]

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Known predators

Anas strepera is prey of:
Accipitridae
Mustela
Vulpes
Homo sapiens
Taxidea taxus
Procyon lotor
Canis latrans

This list may not be complete but is based on published studies.
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Known prey organisms

Anas strepera preys on:
Actinopterygii
algae
Mollusca
Arthropoda
Insecta
Amphibia

This list may not be complete but is based on published studies.
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General Ecology

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).

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Habitat-related Fire Effects

More info for the term: cover

Burning can change the growth form and pattern of nesting cover for
gadwalls [20].  Gadwalls prefer nesting in dense cover [16], which can
be destroyed by fire.  A study of the effects of nesting cover removal
on breeding puddle ducks at Lower Souris National Wildlife Refuge, North
Dakota, showed that after spring burning, nest densities of gadwalls
were greater in areas where the vegetation was not burned [12].
Additionally, gadwall nests were significantly (P less than 0.01) less abundant in
mowed meadows that would be expected by chance.  They made up 29 percent
of all nests found, but only 13 percent of the nests were in mowed
meadows.  Gadwalls will, however, use areas that have been burned if
cover development is sufficent when they begin nesting [12].  Changes in
vegetation cover induced by fire can also benefit gadwalls by destroying
unwanted vegetation and increasing vegetation preffed by gadwalls [15].
  • 12.  Martz, Gerald F. 1967. Effects of nesting cover removal on breeding        puddle ducks. Journal of Wildlife Management. 31(2): 236-247.  [16284]
  • 15.  Schlichtemeier, Gary. 1967. Marsh burning for waterfowl. In:        Proceedings, 6th annual Tall Timbers fire ecology conference; 1967 March        6-7; Tallahassee, FL. No. 6. Tallahassee, FL: Tall Timbers Research        Station: 40-46.  [16450]
  • 16.  Sousa, Patrick J. 1985. Habitat suitability index models: gadwall        (breeding). Biological Report 82(10.100). Washington, DC: U.S.        Department of the Interior, Fish and Wildlife Service. 35 p.  [20031]
  • 20.  Kruse, Arnold D.; Higgins, Kenneth F. 1990. Effects of prescribed fire        upon wildlife habitat in northern mixed-grass prairie. In: Alexander, M.        E.; Bisgrove, G. F., technical coordinators. The art and science of fire        management: Proceedings, 1st Interior West Fire Council annual meeting        and workshop; 1988 October 24-27; Kananaskis Village, AB. Inf. Rep.        NOR-X-309. Edmonton, AB: Forestry Canada, Northwest Region, Northern        Forestry Centre: 182-193.  [14146]

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Timing of Major Life History Events

Breeding and nesting - The gadwall's breeding season varies but usually
occurs in May through mid-July, somewhat later in the northern regions
and earlier in the south [2,11].

Clutch/incubation - Gadwalls lay 5 to 13 eggs per nest, and incubation
is 24 to 28 days [1,13].

Fledge - Gadwalls fledge 7 to 8 weeks after hatching [6].

Maturity - Gadwalls become sexually mature and acquire their breeding
plummage during their first winter [6].

Migration - Gadwalls are one of the last ducks to arrive on breeding
areas in the spring [1]. Some early dates of arrival for various areas
in North America are as follows [2]:

                Southern Iowa - March 10
                Minnesota, Heron Lake - March 17
                Montana - April 1
                Manitoba - April 23
                Saskatchewan - April 18
                Alberta - May 5
  • 1.  Bellrose, Frank C. 1980. Ducks, geese and swans of North America.        Harrisburg, PA: Stackpole Books. 3rd ed. 540 p.  [19802]
  • 11.  Madge, Steve; Burn, Hilary. 1988. Waterfowl: An indentification guide to        the ducks, geese and swans of the world. Boston, MA: Houghton Mifflin        Company. 298 p.  [20029]
  • 13.  Musgrove, Jack W.; Musgrove, Mary R. 1943. Waterfowl in Iowa. Des        Moines, IA: State Convservation Committee. 113 p. + index.  [20028]
  • 2.  Bent, Arthur Cleveland. 1962. Life histories of North American wild        fowl. Part 1. New York: Dover Publications, Inc. 244 p.  [20027]
  • 6.  Johnsgard, Paul A. 1979. A guide to North American waterfowl.        Bloomington, IN: Indiana University Press. 274 p.  [20026]

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Life History and Behavior

Behavior

Perception Channels: visual ; tactile ; acoustic ; chemical

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Diet

aquatic plants, insects, crustaceans, amphibians, mollusks and fish
  • North-West Atlantic Ocean species (NWARMS)
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Life Expectancy

Although there is no data on longevity or mean life expectancy, there was a banded Gadwall in Alaska that was recovered in Louisiana that had reached 19 years of age (Tesky 1997).

Average lifespan

Status: wild:
234 months.

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Lifespan, longevity, and ageing

Maximum longevity: 22.3 years (wild)
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Reproduction

The courtship displays of Gadwall males can be very elaborate. The displays that the males perform range from the Head-Up-Tail-Up (male throws his head back and jerks with his tail feathers erect) to the Grunt-Whistle (male rears out of the water and slowly sinks back down while making a loud whistle). Both the male and accepting female then continues the courtship by performing other displays separately or in unison. Copulation begins with both sexes bobbing their heads up and down and touching their bills to the water horizontally with their necks extended. As the female extends her neck the male mounts her. After copulation the female bathes while the male faces her and then he bathes. There have been reported occurrences of extra-pair copulations. In the late laying and incubation season paired females unaccompanied by their mates have been chased by one to several paired males which occasionally has ended up in rape.If the nest is predated, then the female will usually make another nest and lay a second clutch. (Bellrose 1980, Tesky 1993, LeSchack et al. 1997).

Mating System: monogamous

Gadwalls are monogamous in their breeding behavior. Pairs of adult birds will bond in the mid to late fall, while inmature birds will pair by mid winter. Pair bonds are renewed each year. Most yearlings will mate the following breding season but studies on domestic flocks have showed that sometimes the late hatchlings were not sexually active untill their second year. The breeding season will vary but usually can occur in May and go through mid-July (Johnsguard 1979).

Breeding season: May-July

Range eggs per season: 7 to 12.

Average eggs per season: 9.

Range time to hatching: 24 to 27 days.

Average time to hatching: 26 days.

Range fledging age: 49 to 70 days.

Average fledging age: 63 days.

Range age at sexual or reproductive maturity (female): 10 to 22 months.

Average age at sexual or reproductive maturity (female): 12 months.

Range age at sexual or reproductive maturity (male): 10 to 22 months.

Average age at sexual or reproductive maturity (male): 12 months.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous

Average eggs per season: 9.

The male and the female will fly low over meadows and upland habitat in search of a nesting site. The female will usually choose a nest site near her natal nesting grounds. It is believed that this behavior is from the imprinting of familiar and successful nesting areas. As the male stands guard, the female will inspect an area that has suitable materials for nest building. When an area has been chosen, the female constructs a nest bowl by scraping a depression in the soil. She then lines it with leaves, grasses, and twigs from nearby material. She may then line the nest with down feathers plucked from her body.

She will lay a clutch from 7 to 13 eggs at the rate of one egg per day. The average incubation period will last 26 days with the female spending 85% of her time on the eggs. Many males will abandon the female after the clutch is laid and to a safe area where they will molt to their basic plumage.

The precocial young will hatch and be led by their mother from the vulnerable nest area to brood-rearing habitat. Since the ducklings are precocial, they obtain their own food. The female will raise the brood for no more than 10 weeks and will then abandon her young (Baldsarre et al. 1994, LeSchack et al. 1997).

Parental Investment: precocial

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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.

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Molecular Biology and Genetics

Molecular Biology

Barcode data: Anas strepera

The following is a representative barcode sequence, the centroid of all available sequences for this species.


There are 10 barcode sequences available from BOLD and GenBank.

Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.

See the BOLD taxonomy browser for more complete information about this specimen and other sequences.

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNCTCAGCCTGCTAATCCGCGCAGAACTAGGCCAGCCAGGGACCCTCCTGGGCGACGACCAAATTTATAACGTGATCGTCACCGCTCACGCCTTTGTAATAATCTTCTTCATAGTAATGCCCATCATAATTGGAGGATTCGGCAACTGATTAGTCCCTCTGATAATCGGTGCCCCCGACATAGCGTTCCCACGAATAAACAACATGAGCTTCTGACTCCTCCCACCGTCATTCCTCCTACTACTCGCCTCATCCACCGTAGAAGCTGGCGCTGGCACAGGTTGAACCGTGTACCCGCCCCTAGCAGGCAATCTAGCCCACGCCGGAGCCTCGGTAGACCTAGCTATCTTCTCACTCCACCTAGCCGGGGTCTCCTCCATCCTCGGAGCCATTAACTTCATTACCACGGCCATCAACATAAAACCCCCCGCACTCTCACAATACCAAACCCCACTTTTCGTTTGATCGGTCCTAATTACCGCCATCCTACTCCTCCTATCACTCCCCGTCCTCGCCGCCGGGATCACAATGCTATTAACCGACCGAAACCTAAACACCACATTCTTTGACCCCGCCGGAGGAGGAGACCCAATCCTGTACCAACACCTATTTTGATTCTTTGGCCACCCAGAAGTCTATATCTTAATTCTC
-- end --

Download FASTA File

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Statistics of barcoding coverage: Anas strepera

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 10
Specimens with Barcodes: 13
Species With Barcodes: 1
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Conservation

Conservation Status

There are no conservation plans for the Gadwall at this time. Their populations have been increasing since 1955. With the Conservation Reserve Program (CRP) under the Food Security Act of 1985, the retirement of 14 million acres of cropland in the Prairie Pothole region by 1996 has been attributed to a steady increase of many waterfowl populations including Gadwalls (Tesky 1993, LeSchack et al. 1997).

US Migratory Bird Act: protected

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

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IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2012

Assessor/s
BirdLife International

Reviewer/s
Butchart, S. & Symes, A.

Contributor/s

Justification
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend is not known, but the population is not believed to be decreasing sufficiently rapidly to approach the thresholds under the population trend criterion (>30% decline over ten years or three generations). The population size is extremely large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
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National NatureServe Conservation Status

Canada

Rounded National Status Rank: N5B,N4N : N5B: Secure - Breeding, N4N: Apparently Secure - Nonbreeding

United States

Rounded National Status Rank: N5B,N5N : N5B: Secure - Breeding, N5N: Secure - Nonbreeding

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NatureServe Conservation Status

Rounded Global Status Rank: G5 - Secure

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Status in Egypt

Regular passage visitor and winter visitor.

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Population

Population
The global population is estimated to number c.3,200,000-3,800,000 individuals (Wetlands International 2006), while national population estimates include: c.100-10,000 breeding pairs and c.50-1,000 wintering individuals in China; c.1,000-10,000 wintering individuals in Korea and
Population Trend
Unknown
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Threats

Major Threats
The species is threatened by pollution (Kear 2005b) and disturbance from recreational use of freshwater wetlands (Kear 2005b, Pease et al. 2005). It also suffers mortality as a result of lead shot ingestion (Spain) (Mondain-Monval et al. 2002) and nest predation by American mink Neovison vison (Europe) (Opermanis et al. 2001). The species is susceptible to avian influenza, so may be threatened by future outbreaks (Melville and Shortridge 2006). Utilisation The species is hunted throughout most of its range (Kear 2005b) both for recreation (Bregnballe et al. 2006, Shortridge et al. 2006) and commercial uses (Balmaki and Barati 2006), but is rarely taken in large numbers except where it is particularly abundant (Kear 2005b). The eggs of this species used to be (and possibly still are) harvested in Iceland (Gudmundsson 1979).

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Management

Management Requirements: Wetland management to benefit gadwalls should be directed at maintaining large wetlands with stable water levels suitable for the growth of submersed aquatic vegetation (Ringelman 1990). See Barker et al. (1990) for information on the effects of different livestock grazing systems on nesting success in North Dakota. See Marcy (1986) for specifications for the construction and placement of wire nest baskets.

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Use of Fire in Population Management

More info for the term: succession

Wetlands can be burned to reverse plant succession to a subclimax plant
community which is attractive to waterfowl [15].  Fire can be used to
remove the accumulation of dead vegetation built up on marshes over the
years and restore wetlands that are dominated with plants such as common
reed (Phragmites communis). Desirable gadwall foods such as pondweed can
be restored by burning.  Burning should be postponed until after the
nesting season to avoid destroying nests [15].
  • 15.  Schlichtemeier, Gary. 1967. Marsh burning for waterfowl. In:        Proceedings, 6th annual Tall Timbers fire ecology conference; 1967 March        6-7; Tallahassee, FL. No. 6. Tallahassee, FL: Tall Timbers Research        Station: 40-46.  [16450]

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Management Considerations

More info for the term: cover

Grazing and mowing often destroy preferred nesting cover for gadwalls.
Although annual mowing or grazing is not recommended, mowing may be
useful for maintaining vegetative cover in earlier, more productive
successsional stages [16].

REFERENCES :
NO-ENTRY
  • 16.  Sousa, Patrick J. 1985. Habitat suitability index models: gadwall        (breeding). Biological Report 82(10.100). Washington, DC: U.S.        Department of the Interior, Fish and Wildlife Service. 35 p.  [20031]

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Relevance to Humans and Ecosystems

Benefits

Humans benefit from Gadwalls not as much economically as they do socially and traditionally. Hunting has been a tradition in the North America since the beginning of recorded history. The Native Americans have told of hunting waterfowl in their traditional stories. The hunting of Gadwalls as well as other waterfowl is deeply rooted in traditions of North Americans. Because of the demand by hunters to continue to harvest these birds, the U.S. fish and wildlife service monitors the populations and sets regulations on hunting of waterfowl. This system can be seen to have a positive impact on humans because of the rewards of the food source from hunting. Also money generated from the sale of hunting premits and liscenses helps to maintain and create new waterfowl refuges as well as supplies revenue to monitor populations for the next years hunting regulations (LeSchack et al. 1997).

Positive Impacts: food

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Economic Uses

Comments: Lightly harvested; comprises 4.2% of continental duck breeding population, but only 2.5% of harvest (Ringelman 1990).

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Wikipedia

Gadwall

For other uses, see Gadwall (disambiguation).

The gadwall (Anas strepera) is a common and widespread duck of the family Anatidae.

Systematics[edit]

The gadwall was first described by Linnaeus in 1758 in his Systema naturae, under its current scientific name.[2] DNA studies have shown that it is a sister species with the falcated duck, and that these two are closely related to the wigeons.[3] There two subspecies:[4]

  • A. s. strepera, described by Linnaeus, is the nominate subspecies.
  • A. s. couesi, Coues' gadwall, extinct circa 1874, was formerly found on Teraina, a coral atoll in the Pacific Ocean.[5]

The etymology of the word gadwall is not known, but the name has been in use since 1666.[6]

Description[edit]

A drake

The gadwall is 46–56 cm (18–22 in) long with a 78–90 cm (31–35 in) wingspan.[7] The male is slightly larger than the female, weighing on average 990 g (35 oz) against her 850 g (30 oz).[8] The breeding male is patterned grey, with a black rear end, light chestnut wings, and a brilliant white speculum, obvious in flight or at rest.[9] In non-breeding (eclipse) plumage, the drake looks more like the female, but retains the male wing pattern, and is usually greyer above and has less orange on the bill.[8]

The female is light brown, with plumage much like a female mallard. It can be distinguished from that species by the dark orange-edged bill, smaller size, the white speculum, and white belly.[9] Both sexes go through two moults annually, following a juvenile moult.[7]

The gadwall is a quieter duck, except during its courtship display. Females give a call similar to the quack of a female mallard but higher-pitched, transcribed as gag-ag-ag-ag. Males give a grunt, transcribed as nheck, and a whistle.[8]

Distribution[edit]

The gadwall breeds in the northern areas of Europe and Asia, and central North America. In North America, its breeding range lies along the Saint Lawrence River, through the Great Lakes, Alberta, Saskatchewan, the Dakotas, south to Kansas, west to California, and along coastal Pacific Canada and southern coastal Alaska.[7][9] The range of this bird appears to be expanding into eastern North America. This dabbling duck is strongly migratory, and winters farther south than its breeding range, from coastal Alaska, south into Central America, and east into Idaho, Kansas, Ohio, Virginia, and then south all the way into Central America.[7][9] Its conservation status is Least Concern.[1]

In Great Britain, the gadwall is a scarce-breeding bird and winter visitor, though its population has increased in recent years. It is likely that its expansion was partly through introduction, mainly to England, and partly through colonization to Great Britain, with continental birds staying to breed in Scotland. It has been reported in the River Avon in Hampshire and Wiltshire. In Ireland a small breeding population has recently become established, centred on Wexford in the south and Lough Neagh in the north.[10]

Behaviour[edit]

Nest lined with feathers

The gadwall is a bird of open wetlands, such as prairie or steppe lakes, wet grassland or marshes with dense fringing vegetation, and usually feeds by dabbling for plant food with head submerged. It nests on the ground, often some distance from water. It is not as gregarious as some dabbling ducks outside the breeding season and tends to form only small flocks. This is a fairly quiet species; the male has a hoarse whistling call, and the female has a Mallard-like quack. The young birds are fed insects at first; adults also eat some molluscs and insects during the nesting season. The gadwall is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies.

References[edit]

  1. ^ a b BirdLife International (2012). "Anas strepera". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013. 
  2. ^ Linnaeus, C. (1758). Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata. (in Latin). Holmiae [Stockholm]: Laurentii Salvii. p. 125. Retrieved 10 August 2014. A. macula alarum rufa nigra alba. 
  3. ^ Johnson, Kevin P.; Sorenson, Michael D. (1999). "Phylogeny and biogeography of dabbling ducks (genus: Anas): A comparison of molecular and morphological evidence" (PDF). The Auk 116 (3): 792–805. doi:10.2307/4089339. 
  4. ^ "ITIS Report: Anas strepera". Integrated Taxonomic Information System. Retrieved 10 August 2014. 
  5. ^ Hume, Julian P.; Walters, Michael (2012). Extinct Birds. London, UK: T. & A. D. Poyser. p. 48. ISBN 978-1-4081-5725-1. Retrieved 10 August 2014. 
  6. ^ "gadwall". Merriam-Webster. Retrieved 24 August 2011. 
  7. ^ a b c d Floyd, 2008[page needed]
  8. ^ a b c Madge, Steve; Burn, Hilary (1988). Wildfowl: An Identification Guide to the Ducks, Geese and Swans of the World. Christopher Helm. pp. 200–202. ISBN 0-7470-2201-1. 
  9. ^ a b c d Dunn and Alderfer, 2006[page needed]
  10. ^ Irish Birds 9: 68. 2010. 

Literature cited[edit]

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Names and Taxonomy

Taxonomy

Comments: 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.

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Common Names

gadwall
gray (grey) duck
gray mallard
gray widgeon
redwing

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The currently accepted scientific name for the gadwall is Anas strepera
Linnaeus. There are no recognized subspecies [1,6].
  • 1.  Bellrose, Frank C. 1980. Ducks, geese and swans of North America.        Harrisburg, PA: Stackpole Books. 3rd ed. 540 p.  [19802]
  • 6.  Johnsgard, Paul A. 1979. A guide to North American waterfowl.        Bloomington, IN: Indiana University Press. 274 p.  [20026]

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