35 Colorado Ducks, Geese, and Swans: ID, Habitat & Sound Guide

Identify Colorado’s ducks, geese, and swans with this streamlined guide. This resource features detailed accounts for 35 species, covering plumage, natural history, and calls, organized by taxonomic groups. We also include a dedicated section on urban, domestic, and feral ducks to help you confidently recognize any waterfowl found in the Centennial State.

How to use this Guide

Click on any of the four major groups below (DABBLING DUCKS, DIVING DUCKS, GEESE, and SWANS) to explore the species included in each category, including their detailed subgroups. You can also use the Table of Contents below this section to browse the entire guide.

Exploring Essential Concepts and Definitions

This state-specific guide focuses on the local status and occurrence of waterfowl in Colorado. However, to master key terminology and understand the science behind identification, you may wish to dig deeper into the foundational concepts. If you’re curious about topics like the “Big Divide” between Dabbling vs. Diving Ducks“, the function of their anatomy, how to identify plumage cycles, or the principles of migration and conservation across North America, these subjects are thoroughly explained in our comprehensive resource.

For an exhaustive breakdown of all definitions, concepts, and techniques used in this guide, please follow the link below to the main pillar page: Complete Guide to Ducks, Geese, and Swans of North America.

Ducks, Mergansers, Geese, and Swans in Colorado

This guide features the ducks, mergansers, geese, and swans that occur in Colorado. While most North American waterfowl species have been recorded here as vagrants or accidental visitors, this guide focuses on species whose official range includes the Lone Star State, as documented by the eBird/Science platform.

At the end, you’ll also find a section on domestic and feral species commonly seen in city parks and retention ponds. Because Colorado’s wetlands are biodiverse, you will often find waterfowl sharing these habitats with other bird species. For a complete picture of the state’s avian life, you can explore our dedicated guide to the Wetland Birds of Colorado including cranes, grebes, snipes, ibises, spoonbills, rails, among others.

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DABBLING DUCKS OF COLORADO

The Dabbling Ducks are the most commonly encountered waterfowl in the State, recognized by their habit of feeding in shallow water. They rarely fully submerge, instead feeding by tipping up to reach submerged plants and invertebrates—leaving only their tail feathers visible. Their legs are centrally placed, allowing them to walk easily on land and launch straight up into the air when taking flight.

Core Dabbling Ducks (Anas/Spatula/Mareca)

Blue-winged Teal (Spatula discors)

Identification: Drake: slaty-blue head, white crescent behind bill, speckled brown body. Hen: brown, has a pale area at base of bill. Both sexes reveal bold powder-blue wing patches on the upper wing.
Compare: Hen Green-winged Teal is darker, and has a different wing color pattern. Hen Cinnamon Teal is warmer-toned overall, has a longer a more spatulated bill, and duller face pattern. Learn the subtle field marks to distinguish the Female Blue-winged Teal from the Female Cinnamon Teal.
Behavior: Dabbling duck, tips up or submerges head/bill for food. Monogamous; pair bonds usually dissolve during incubation.
Flocking: The Blue-winged Teal forms small compact flocks that twist and turn at high speed. Flocks often fly low over marshes. It frequently mixes with other dabbling ducks.
Habitat: Shallow ponds, pond-marsh mixes, marshes, vegetated wetlands, rice fields, estuaries, mangroves.
Range: Breeds across much of North America; winters southern US to Central and South America.
Status and Movements: The Blue-winged Teal is a common summer resident and transient in Colorado, arriving in early spring to breed and departing by early fall. This dabbler favors shallow wetlands.
Diet: Aquatic insect larvae, crustaceans, clams, snails, and grains.
Nest: Small circular depression scraped by female. Lined with dried grasses and down/breast feathers.
Breeding: Egg laying: late Apr-Aug | Clutch: 6-14 eggs | Broods: 1 brood | Eggs: Creamy white | Incubation: 19-29 days.
Lifespan: At least 23 years, 3 months.
Population: Global breeding population estimated at 7.8 million individuals. The Blue-winged Teal is the second most abundant duck in North America.

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Cinnamon Teal (Spatula cyanoptera)

Identification: Drake vivid rusty plumage, red eye. Hen/immature: rich brown overall. Both sexes have dark somewhat spatulated bill and large blue patches on the upper wing.
Compare: Hen Green-winged Teal is darker, and has a green wing speculum. Hen Blue-winged Teal is colder brown and has a pale area at the base of a shorter and narrower bill. Learn the subtle field marks to distinguish the Female Blue-winged Teal from the Female Cinnamon Teal.
Behavior: Dabbling duck. Forages at water surface; tips up to strain seeds/insects with bill. Pairs form late winter/spring. Males guard mates until incubation.
Flocking: The Cinnamon Teal flies in pairs or very small flocks during the summer breeding season, and in small, highly maneuverable flocks during migration. It frequently associate with Blue-winged Teals and the Northern Shoveler into larger flocks.
Habitat: Freshwater wetlands, emergent vegetation, marshes, ponds, lakes, streams, reservoirs, wet agricultural fields, tidal estuaries, mangrove swamps.
Range: Breeds interior western North America. Winters Mexico.
Status and Movements: The Cinnamon Teal is a common summer resident and transient in Colorado. This vibrant dabbler arrives in spring, breeds in marshy areas, and migrates south by early fall.
Diet: Aquatic plant seeds, aquatic vegetation, zooplankton, insects, snails, beetles, midges, bulrush, smartweed.
Nest: Depression lined with rushes, grass, down. Often concealed below matted dead stems, approached via tunnels.
Breeding: Breeding Months: late Mar-mid-Sep | Clutch: 4-16 eggs | Broods: 1-2 broods | Eggs: Creamy white | Incubation: 21-25 days.
Lifespan: At least 10 years, 6 months.
Population: Global breeding population estimated at 380,000 individuals. The Cinnamon Teal is on the Yellow Watch List for declining populations.

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Northern Shoveler (Spatula clypeata)

Identification: Breeding Drake: Northern Shoveler has bright green head, white chest, rust sides. Hen/immature: mottled brown, large orange bill, blue wing patches. Unique shovel-shaped bill.
Compare: Drake and hen Northern Shoveler share their wing color pattern with Cinnamon and Blue-winged teals, but shovelers are noticeably larger. Hen has a large orangish and spatulated bill.
Behavior: Tips up and sweeps bill side to side to filter tiny prey. Large groups sometimes swim in circles to stir up food. Pairs stay together until almost fall migration.
Flocking: Flight is steady and direct typically in flocks of 5 to 20 birds during the non-breeding season. During the breeding season groups are generally limited to pairs. Northern Shovelers gather in larger rafts or flocks at major migratory stopovers.
Habitat: Shallow wetlands, coastal marshes, rice fields, flooded fields, lakes, sewage lagoons.
Range: Breeds across North America; winters southern U.S. south to Central America and Caribbean.
Status and Movements: The Northern Shoveler is a common summer resident and transient in Colorado, with some individuals wintering. It is most abundant during spring and fall migrations across the state.
Diet: Tiny crustaceans, aquatic invertebrates, seeds.
Nest: Small depression on ground. Lined with downy feathers. Surrounded by vegetation, typically within 150 feet of water.
Breeding: Egg laying: May-Jun | Clutch: 8-12 eggs | Broods: 1 brood | Eggs: Pale greenish gray or olive-buff | Incubation: 22-25 days.
Lifespan: At least 16 years, 7 months.
Population: Global breeding population estimated approx. 5.9 million individuals.

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Gadwall (Mareca strepera)

Identification: Drake intricate gray-brown pattern, black rear end. Hen patterned brown/buff, thinner dark bill with thin orange edge. Both sexes show a white wing patch.
Compare: Hen Gadwall is similar to other female teals but has an orange line along the edge of the bill. Both sexes have a distinctive white wing patch. Hen Mallard has a large blue wing speculum.
Behavior: Tips forward for submerged vegetation, rarely dives. Pairs form early, often in late fall. Seasonally monogamous.
Flocking: The Gadwall flies swiftly in a small to medium size flocks, often in a nervous, irregular fashion with many twists and turns.
Habitat: Prairie potholes, Canadian prairies, tundra, boreal forest wetlands, fresh/salt water wetlands.
Range: The Gadwall breeds primarily in the Great Plains and Canadian prairies; winters across the southern U.S. and Mexico.
Status and Movements: The Gadwall is a common resident and transient in Colorado, breeding widely across the state. While some winter, populations swell during spring and fall migrations on open water.
Diet: Mostly submerged aquatic vegetation, snails, midges, water beetles.
Nest: Hollow scrape on ground, lined with twigs, leaves, down.
Breeding: Egg laying: mid-Apr-Jun | Clutch: 7-12 eggs | Broods: 1 brood | Eggs: N/A | Incubation: 24-27 days
Lifespan: At least 19 years, 6 months.
Population: Approximately 4.4 million individuals.

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American Wigeon (Mareca americana)

Identification: Drake: gray head with a white forehead and crown, green patch behind the eye, cinnamon body, large white wing patch. Bill: pale gray, black tip, white rump. Hen: plainer brown with rusty sides.
Compare: Drake American Wigeon differ from drake Eurasian Wigeon due to a chestnut head and a buffy forehead. Hen Eurasian has a warmer orangey head, but difficult to separate from hen American.
Behavior: Forages on the surface or tips up for aquatic plants; plucks terrestrial plants with short bill. Quite vocal; distinctive whistle.
Flocking: The American Wigeon is highly social outside of breeding season, forming large noisy flocks on water and grazing fields.
Habitat: Freshwater wetlands, lakes, slow rivers, marshes, estuaries, bays, grasslands, pastures, golf courses.
Range: Breeds Alaska, Canada, Northwest U.S.; winters southern U.S. and Mexico.
Status and Movements: The American Wigeon is a common transient and winter visitor in Colorado, with some breeding. It is most frequently observed from late fall through early spring across the state.
Diet: Aquatic plants. Upland plants. Invertebrates (midges, mollusks).
Nest: Small depression on dry ground, sometimes far from water. Lined with grasses, reeds, cattails, and down feathers.
Breeding: Egg laying: Early May-Jun | Clutch: 3-13 eggs | Broods: 1 brood | Eggs: Creamy white | Incubation: 22-28 days.
Lifespan: At least 21 years, 4 months.
Population: Approximately 2.7 million individuals.

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Eurasian Wigeon (Mareca penelope)

Identification: Drake: gray body, bright rufous head, buffy-cream forecrown, large white wing patch. Hen: mostly brown, some rufous on flanks/head. Juveniles resemble females. Bill: black-tipped, blue-gray.
Compare: Drake is similar to a drake American Wigeon, which has a gray head and white forehead and crown. Hen American has a colder gray head.
Behavior: Forages in flocks, tips up for submerged plants. Males court with ritual movements, often gathered around one female.
Flocking: The Eurasian Wigeon is highly gregarious outside of breeding season. In North America, they are almost invariably found mixed within large flocks of American Wigeon.
Habitat: Shallow wetlands, freshwater marshes, ponds, lakes. Winters: coastal sites, estuaries, bays, brackish lagoons.
Range: Rare visitor to North America. Winters Pacific/Atlantic coasts (Iceland/Asia origin).
Status and Movements: The Eurasian Wigeon is a rare but regular winter visitor and transient in Colorado. Look for this distinctive wigeon from late fall through early spring, often with American Wigeons.
Diet: Aquatic/terrestrial plants. Grasses, cultivated rice, wheat, barley, potato. Invertebrates.
Nest: Shallow depression on ground. Near small pond/marsh or upland site. Lined with grasses and female breasts down.
Breeding: Does not breed in NA | Clutch: 6-12 eggs | Eggs: Buffy in color | Incubation: 22-28 days.
Lifespan: At least 33 years, 7 months (Europe).
Population: Worldwide breeding population estimated at 2 million individuals.

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Mallard (Anas platyrhynchos)

Identification: Drake: iridescent green head, yellow bill, gray flanks, pale tail with black tail-curls. Hen/Juvenile: mottled brown, orange bill with dark patch. Both sexes show white-bordered, blue speculum.
Compare: The hen Mallard differs from hens American Black Duck, Mottled Duck, and Mexican Duck due to a warmer brown body, black and orange bill, and bold white wing bars on the leading and trailing edges of the blue wing speculum. Learn the subtle field marks to distinguish the American Black Duck from the Female Mallard.
Behavior: Dabbling duck, tips forward to graze; rarely dives. Generally monogamous, pairs form in fall.
Flocking: Mallards are social and gregarious outside of breeding season. They form large, loose flocks (up to hundreds of birds) often mixing with other dabblers.
Habitat: Ponds, lakes, marshes, rivers, coastal habitats, estuaries and City parks.
Range: Widespread throughout North. Breeds far north; year-round/winter in central/southern U.S. and Mexico.
Status and Movements: The Mallard is an abundant resident throughout Colorado, present year-round. Its numbers are augmented by transients and winter visitors, making it the state’s most widespread duck.
Diet: Seeds, aquatic vegetation, insect larvae, freshwater shrimp. Agricultural grain, human handouts.
Nest: Shallow bowl/depression on ground near water, concealed under vegetation.
Breeding: Egg laying: Early-Apr-Jul | Clutch: 1-13 eggs | Broods: 1-2 | Eggs: Creamy to grayish or greenish buff | Incubation: 23-30 days.
Lifespan: At least 27 years, 7 months.
Population: Estimated population around 19 million individuals.

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Mexican Duck (Anas diazi)

Identification: Male is dull cinnamon with a dull yellowish bill. The female is buffy with a mottled orange/black bill. Both sexes resemble a female Mallard.
Compare: Similar to a female Mallard, but noticeably darker. Hybridizes with Mallards producing birds with intermediate features.
Behavior: Forages agricultural crops during dry season. Monogamous, pair bond length unclear. Usually wary, but sometimes tame in urban settings.
Flocking: Usually in pairs or small flocks. Forms large flocks that grow as the dry season progresses and small habitats shrink.
Habitat: Lakes, reservoirs, large streams, temporary marshes, farm ponds, agricultural landscapes.
Range: Extreme southwestern U.S. (South Texas) and Central Mexico, where 98% of the population resides.
Status and Movements: The Mexican Duck is an uncommon resident in southern Colorado, present year-round. This species is often difficult to distinguish from female Mallards in the field.
Diet: Grains, seeds, aquatic plant tubers, invertebrates (breeding season protein).
Nest: Shallow cup lined with down. Built on ground, among dense wheat stubble/sorghum, usually far from water.
Breeding: Egg laying: Feb-early Jul | Clutch: 2-10 eggs | Eggs: White, faint bluish-green hue | Incubation: 26 days
Lifespan: Not known.
Population: Approximately 55,000 individuals. Body Measurements: Length: 19.65 in (Average of 17.7-21.6 in) Weight: 36.9 oz (Average of 29.9-43.9 oz) Wingspan: N/A

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Northern Pintail (Anas acuta)

Identification: Drake: chocolate head/neck, white breast/stripe down neck, long pointed tail. Hen/immature: mottled brown, pale tan face, bluish-gray bill.
Compare: The hen is similar to other hen teals and hen Mallard, Mottled and American Black Ducks. The hen Pintail has a warmer brown head, long neck, and distinctive bluish-gray bill.
Behavior: Dabbling duck. Forages on surface or tips up, filters food with bill. Generally social.
Flocking: The Northern Pintail is highly social, forming large, loose flocks (often hundreds) in winter. Flocks are known for fast, graceful flight in long, wavering lines or V-formations. Often feed and roost with American Wigeon.
Habitat: Seasonal wetlands, croplands, wet meadows, shortgrass prairies, lakes, estuaries, tidal marshes, flooded agricultural fields.
Range: Breeds Alaska, Canada, Great Plains; winters southern U.S. and Mexico.
Status and Movements: The Northern Pintail is a common transient and winter visitor in Colorado, with some breeding. This elegant duck is most prevalent from late fall through early spring across the state.
Diet: Aquatic plant seeds, worms, snails, crustaceans, aquatic insects, small grains.
Nest: Shallow bowl on ground, far from water. Female makes scrapes, lines nest with grasses/down.
Breeding: Egg laying: Apr-mid-Jun | Clutch: 3-12 eggs | Broods: 1 brood | Eggs: Greenish buff | Incubation: 22-24 days.
Lifespan: At least 22 years, 3 months.
Population: Global breeding population estimated at 5.1 million individuals.

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Green-winged Teal (Anas crecca)

Identification: Smallest dabbling duck. Drake: cinnamon head, gleaming green eye crescent, white vertical stripe on shoulder. Hen: mottled brown, yellowish tail streak. Both show green speculum.
Compare: Hen is similar to other teals and hen Mallard but differs due to a tiny size, darker overall, and green wing speculum.
Behavior: Dabbling duck. Forages shallow wetlands by tipping up or picking while standing in puddles. Quite vocal. Pairs form fall/winter.
Flocking: The Green-winged Teal is highly gregarious, forming tight, dense flocks of up to hundreds of birds. Flocks perform fast, highly erratic movements and sudden, synchronized turns in flight; renowned for their speed and agility.
Habitat: Shallow ponds, flooded fields, coastal marshes, estuaries, river deltas, boreal forest wetlands, sedge meadows, beaver ponds.
Range: Breeds widely across northern North America (Canada/Alaska). Winters in southern U.S. and Mexico.
Status and Movements: The Green-winged Teal is a common transient and winter visitor in Colorado, with some breeding. This small dabbler is abundant from late fall through early spring across the state.
Diet: Aquatic invertebrates, seeds, sedge fruit, pondweeds, grasses, rice, corn.
Nest: Well-concealed depression on ground, typically within 200 yards of water. Lined with grasses, sedges, leaves, down.
Breeding: Egg laying: mid-Apr-late Jul | Clutch: 6-9 eggs | Broods: 1-2 | Eggs: Creamy white to pale olive-buff | Incubation: 20-23 days.
Lifespan: At least 20 years, 3 months.
Population: Global breeding population estimated at 6.7 million individuals.

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Native Specialized Dabblers

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Wood Duck (Aix sponsa)

Identification: Drake vivid colors: glossy green head, white stripes, chestnut breast, buff sides. Hen gray-brown, white-speckled breast. Juveniles are similar. Unique crested head. The Wood Duck is often called a “perching duck,” but feeds primarily by dabbling.
Compare: The hen Wood Duck is similar to many other hen ducks, but is distinguished by a bold eye ring, distinctive gray crest, and longish tail. Habitat choice is crucial.
Behavior: Dabbling duck, dives shallowly. Perches, nests in trees. Head jerks when swimming. Pairs form January; bond dissolves after eggs laid.
Flocking: The Wood Duck is less gregarious than many ducks; typically found in pairs or small, loose family groups. Larger flocks (50+) may form during fall migration or roosting at dusk. Flight is fast, direct, and often through dense timber.
Habitat: Wooded swamps, marshes, streams, beaver ponds, small lakes, tree cavities, forested wetlands, bottomland forests.
Range: Found in wooded swamps, streams, and lake edges across North America.
Status and Movements: The Wood Duck is a common summer resident and transient in Colorado, breeding in wooded wetlands. Some individuals may overwinter, but most depart by late fall.
Diet: Seeds, fruits, insects, arthropods. Acorns, soybeans, smartweed, duckweed, millet, grain, wild cherries, beetles, snails.
Nest: Tree cavity or woodpecker hole, 2–60 feet high. Lined with down feathers and wood chips.
Breeding: Egg laying: early Apr-Jun (Pairs form Jan) | Clutch: 6-16 eggs | Broods: 1-2 broods | Eggs: Glossy creamy white to tan | Incubation: 28-37 days. Egg-dumping common, especially in nest boxes.
Lifespan: At least 22 years, 6 months.
Population: Estimated at approximately over 3 million birds.

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DIVING DUCKS OF COLORADO

The Diving Ducks are built for life beneath the water’s surface. Unlike dabblers, their legs are set far back on their bodies, which provides maximum propulsion underwater but makes them clumsy on land. To take flight, they must run, or “patter,” across the water’s surface to gain enough speed. This group primarily forages in deeper lakes, large rivers, and coastal bays.

Core Colorado Diving Ducks (Aythya)

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Canvasback (Aythya valisineria)

Identification: Drake: Rusty head/neck, gleaming whitish body, black chest/rear. Hen: Grayish/brown body, dark eyes. Both have long sloping foreheads and black bill.
Compare: Redheads have a similar color pattern but are smaller, with a steeper forehead, a gray (not white) back, and a bluish (not black) bill. Learn the subtle field marks to distinguish the Canvasback from the Redhead.
Behavior: Diving duck, gregarious nonbreeding season. Dives underwater constantly. Rarely goes ashore. It often forms large rafts.
Flocking: The Canvasback is highly social, forming massive, dense rafts (thousands) on large lakes. Flocks fly in long, swift, oblique lines or V-formations with powerful, sustained speed. They are the fastest fliers of North American ducks.
Habitat: Lakes, deep-water marshes, ponds, estuaries, coastal waters, lagoons, rivers, flooded agricultural fields.
Range: Breeds lakes/marshes Prairie Pothole Region, Canada, Alaska. Winters US coasts/inland waters, Mexico. This Canvasback is widespread.
Status and Movements: The Canvasback is a common transient and winter visitor in Colorado. This distinctive diving duck is observed from late fall through early spring on larger bodies of water.
Diet: Plant tubers, rhizomes, aquatic plant seeds, wild celery, mussels, clams, insects.
Nest: Large bulky platform of sedges, reeds, rushes. Loosely woven, floats on water, attached to emergent stalks.
Breeding: Egg laying mid Apr-early Jul | Clutch: 5-11 eggs | Broods: 1 | Eggs: Greenish drab | Incubation: 24-29 days.
Lifespan: At least 22 years, 7 months.
Population: Estimated breeding population is 566,000.

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Redhead (Aythya americana)

Identification: Drake: Gleaming cinnamon head, black breast/tail, neat gray body. Hen/immature: uniform brown. Both sexes: black-tipped, gray bill, smoothly rounded head.
Compare: Canvasbacks have a similar color pattern but are larger, with a sloping forehead (triangular head), a white (not gray) back, and a black (not bluish) bill. Learn the subtle field marks to distinguish the Canvasback from the Redhead.
Behavior: Sociable duck. Usually dives for food, may tip up in shallow water like dabbling ducks. Monogamous; males court female with gymnastic “head throw” display.
Flocking: The Redhead is highly social, forming large, dense rafts on open water (often thousands). Flocks fly in tight, changing patterns or long, wavy lines with rapid, shallow wingbeats. Often flies with scaups and Canvasbacks.
Habitat: Seasonal wetlands, prairie potholes, deep marsh, large lakes, reservoirs, coastal bays, Gulf Coast, agricultural fields.
Range: Breeds Great Plains/Midwest prairie pothole region, West. Winters Gulf Coast, Great Lakes, southern U.S. waters.
Status and Movements: The Redhead is a common summer resident, transient, and winter visitor in Colorado. This diving duck breeds across the state and is present year-round, with peak numbers during migration.
Diet: Submerged aquatic plants, green algae. Invertebrates: snails, zebra mussels, mayflies, small clams.
Nest: Circular woven bowl built by female using plant material on an underwater vegetation foundation. Found in cattails/bulrushes over water.
Breeding: Egg laying: May-late Jul | Clutch: 7-8 eggs | Broods: 1 | Eggs: Creamy white to pale, olive buff/buffy brown | Incubation: 22-28 days
Lifespan: At least 20 years, 7 months.
Population: North American population estimated at 1.2 million Redhead individuals (2015).

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Ring-necked Duck (Aythya collaris)

Identification: Drake: black/gray, peaked head, prominent white bill ring, black back, white chest (area) spur. Hen: rich brown, pale cheek, whitish eye ring/bill patch.
Compare: Drake Lesser Scaups have a pale back, lack the white side spur, and the white band and black tip of the bill of the Ring-necked. Hen scaups have a solid dark-brown head, not the capped look of the hen Ring-necked Duck.
Behavior: Diving duck. Forages diving for mollusks, invertebrates, submerged vegetation. Uses displays (head throw, nodding) for courtship and rival warnings.
Flocking: The Ring-necked Duck typically forms medium-sized flocks, flying swiftly and directly in loose V-formations or irregular groups. Their agile flight, characterized by quick wingbeats, makes them appear energetic.
Habitat: Freshwater marshes, bogs, beaver ponds, shallow lakes, flooded agricultural fields, cattle ponds, river floodplains, brackish estuaries, reservoirs.
Range: Breeds far northern North America boreal forest. Winters widely US inland/coastal waters, Mexico, Central America/Caribbean.
Status and Movements: The Ring-necked Duck is a common transient and winter visitor in Colorado. This diving duck is frequently seen on open water from late fall through early spring.
Diet: Submerged plants and seeds, aquatic invertebrates, mollusks, earthworms, leeches.
Nest: Simple bowl of sedges/plants on/over water or floating vegetation. Flimsy collection of bent stems, lined with down feathers.
Breeding: Egg laying: early May-mid-Jul | Clutch: 6-14 eggs | Broods: 1 | Eggs: N/A | Incubation: 25-29 days.
Lifespan: At least 20 years, 5 months.
Population: Global breeding population estimated at 2 million individuals.

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Greater Scaup (Aythya marila)

Identification: Drake black/white, rounded head, iridescent green sheen. Blue bill, yellow eye. Hen brown, darker head, variable white bill patch. Nonbreeding mottled gray/brown.
Compare: Drake and hen Lesser Scaup usually show a peak at the back of the head, while Greater Scaup has a more smoothly rounded head. Overall, very similar species. Learn the subtle field marks to distinguish the Lesser Scaup from the Greater Scaup.
Behavior: Diving duck. Forages underwater for aquatic invertebrates/plants, diving up to 23 feet. Monogamous seasonally; pairs form in winter.
Flocking: Greater Scaup are highly gregarious, often forming immense, dense rafts. Their powerful, fast flight occurs in coordinated, tightly packed flocks, often shifting patterns over water, exhibiting strong, direct movement.
Habitat: Shallow lakes, ponds, treeless wetlands, tundra. Coastal bays, reservoirs, Great Lakes, Pacific/Atlantic shorelines.
Range: Breeds North American tundra. Winters Pacific/Atlantic coasts, Great Lakes, reservoirs.
Status and Movements: The Greater Scaup is an uncommon transient and winter visitor in Colorado. Look for this diving duck on larger reservoirs and lakes from late fall into early spring.
Diet: Aquatic invertebrates, mollusks, insects, crustaceans. Aquatic plants, seeds.
Nest: Saucer-shaped depression on ground, near water, dense cover. Lined with grasses, plant material, downy feathers.
Breeding: Egg laying: mid-May – late Aug | Clutch: 5-13 eggs | Broods: 1 | Eggs: Brownish olive-buff | Incubation: 23-28 days.
Lifespan: At least 20 years, 5 months.
Population: Estimated 780,000 individuals. The Greater Scaup is listed as a common bird in steep decline.

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Lesser Scaup (Aythya affinis)

Identification: The Lesser Scaup Drake: Black/white, peaked head, iridescent purple/green sheen, bluish bill/yellow eye. Hen: brown, pale bill patch variable.
Compare: Drake and hen Greater Scaup usually show a more rounded head, while Lesser Scaup shows a peak at the back of the head. Overall, very similar species. Learn the subtle field marks to distinguish the Lesser Scaup from the Greater Scaup.
Behavior: Diving duck. Sleeps on water. Seasonally monogamous, new mates yearly. Drakes display vigorously courting females.
Flocking: The Lesser Scaup typically forms smaller, yet still gregarious, flocks than its larger cousin. They fly swiftly and directly, often in erratic or loose V-formations with rapid wingbeats, showing agile aerial maneuvers.
Habitat: Prairie potholes, boreal forest, tundra wetlands, hayfields. Lakes, reservoirs, coastal bays, estuaries, agricultural ponds.
Range: Breeds Northern North America/Prairie Potholes. Winters US inland/coastal waters, extending south to Central America/Caribbean.
Status and Movements: The Lesser Scaup is a common transient and winter visitor in Colorado. This diving duck is frequently observed on open water from late fall through early spring.
Diet: Aquatic invertebrates: mollusks, insects, crustaceans. Aquatic plants, seeds.
Nest: Saucer-shaped depression on ground in tall, well-concealed vegetation (prairies/marshes). Lined with grasses and female down.
Breeding: Egg laying: late May-Jul | Clutch: 6-14 eggs | Broods: 1 | Eggs: Pale to dark olive/greenish buff | Incubation: 21-27 days.
Lifespan: At least 18 years.
Population: Global breeding population estimated at 3.8 million individuals.

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Subgroup: Sea Ducks

Sea ducks are specialized diving waterfowl of coastal marine habitats, breeding in northern latitudes. Groups include eiders, scoters, mergansers, goldeneyes, long-tailed ducks, harlequin ducks, and buffleheads. Winter mainly at sea; use inland lakes and rivers during migration and breeding.

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Surf Scoter (Melanitta perspicillata)

Identification: Drake jet black, orange/white/black bill, white nape/forecrown patches. Hen dark brown, dark bill, usually two white face patches.
Compare: White-winged Scoters have a large white patch in the wing that Surf Scoters lack. Surf Scoters have distinctive white patches on the forehead and back of the neck. Hens have a darker cap than White-winged Scoters.
Behavior: Dives for prey, often just before ocean waves break. Rests on water. Drake defends moving area around hen during breeding.
Flocking: Surf Scoters typically form smaller flocks, often flying in loose, undulating lines or irregular groups low over the waves. Their direct, powerful flight exhibits purposeful movement, characterized by strong, steady wingbeats. Roosts miles offshore nightly.
Habitat: Taiga shield ecotone, shallow lakes, boreal forest/tundra blend, ocean coasts, bays, estuaries, inland lakes (migration/storms).
Range: Breeds N. Canada/Alaska boreal forest/tundra. Winters Atlantic/Pacific coasts, inland waters. The Surf Scoter is widespread.
Status and Movements: The Surf Scoter is a rare but regular transient and winter visitor in Colorado. This distinctive sea duck is occasionally found on large reservoirs from late fall to early spring.
Diet: Mollusks (mussels, clams), marine snails, crabs, worms, herring spawn. Aquatic vegetation. Freshwater invertebrates/insects (breeding).
Nest: Well concealed depression on ground. Beneath vegetation/rocky ledges. Lined with down, moss, grasses, needles, twigs, bark.
Breeding: Egg layin: mid May – mid-Aug | Clutch: 6-9 eggs | Broods: 1 | Eggs: Creamy white | Incubation: 28-30 days.
Lifespan: At least 19 years, 7 months.
Population: Global breeding population estimated at 470,000 individuals.

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White-winged Scoter (Melanitta deglandi)

Identification: Drake velvety black, white comma eye patch, orange-tipped bill, white wing patch. Hen dark brown, two smudgy white face patches. Juveniles similar to hens.
Compare: Drake Surf Scoters have a large white patch on the forehead and back of the neck that Drake White-winged Scoters lack. Hens have a uniform dark head that contrasts with the dark-capped head of a hen Surf Scoter.
Behavior: Forages diving deep underwater. Swallows prey whole underwater. Winters in flocks. Monogamous mating system presumed.
Flocking: White-winged Scoters typically form small, loose flocks, flying with strong, direct wingbeats. Their flight is powerful and steady, often staying low over coastal waters, occasionally gathering in larger, dispersed rafts.
Habitat: Boreal forest, shallow freshwater lakes, brushy shrubs (breeding). Coastal areas, shallow saltwater bays, estuaries, Great Lakes (winter).
Range: Breeds Northern Canada/Alaska boreal forest. Winters Atlantic/Pacific coasts, Great Lakes, inland waters. This White-winged Scoter is widespread.
Status and Movements: The White-winged Scoter is a rare but regular transient and winter visitor in Colorado. This large sea duck is occasionally observed on expansive waters from late fall through early spring.
Diet: Mollusks (mussels, clams, snails), crustaceans, fish, insects (freshwater: caddisflies/midges), aquatic plants (small amounts).
Nest: Depression in soil, beneath heavy, thorny vegetation (roses/berry bushes). Fluffy bowl of down/grasses/twigs.
Breeding: Egg laying: Jun-mid-Aug | Clutch: 6-16 eggs | Broods: 1 | Eggs: Creamy buff or light pink | Incubation: 28-30 days.
Lifespan: At least 18 years, 1 month.
Population: Global breeding population estimated at 400,000 individuals.

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Black Scoter (Melanitta americana)

Identification: Drake all jet black, orange knob at base of bill. Hen dark brown, pale face and delineated dark cap.
Compare: White-winged Scoters have a white patch in the wing that Black Scoters lack. The orange bill knob in Black Scoters is distinctive. Hen Black Scoter have a pale face and delineated dark cap.
Behavior: Dives for shellfish/mussels (winter); marsh insects (summer). Drakes vocal, croon. Monogamous, males closely guard mates.
Flocking: Black Scoters gather in moderate to large flocks, maintaining tight, often crescent-shaped flight patterns. They exhibit strong, direct flight with steady, powerful wingbeats, frequently moving low over the water in cohesive groups.
Habitat: Coastal ocean waters, bays, inland lakes/rivers, boreal forest lakes, shallow water, rocky bottoms.
Range: Breeds far north boreal forest/tundra; winters Atlantic/Pacific coasts, Great Lakes, inland waters, scarce southern US.
Status and Movements: The Black Scoter is a rare winter visitor and transient in Colorado. Look for this sea duck on large reservoirs from late fall through early spring, though sightings are infrequent.
Diet: Mollusks (mussels, clams, scallop), crustaceans, insects/larvae, fish eggs, marine vegetation (eelgrass).
Nest: Depression on ground, grassy/sheltered spot, usually <100 feet from water. Lined with female’s down feathers.
Breeding: Egg laying: mid-May – mid-Aug | Clutch: 8-9 eggs | Broods: 1 | Eggs: Off-white to pinkish buff | Incubation: 27-28 days.
Lifespan: At least 10 years, 6 months.
Population: Global breeding population estimated at 900,000 individuals.

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Long-tailed Duck (Clangula hyemalis)

Identification: Drake: stunning black/white in winter; dark/white face patch summer. Extravagantly long tail plumes (male). Hen/immature smudgy brown/white, brown crown/cheek patch, dark bill.
Compare: Shares the long and slender tail feathers with the Northern Pintail, but the head color pattern and bill color are different.
Behavior: The Long-tailed Duck is a strong swimmer, active diver, often reaching 200 feet deep to forage. Thought monogamous; pairs lasting many seasons.
Flocking: Highly social when not breeding. Can form large flocks, often far offshore. Occasionally mixes with other diving duck species. Flight erratic.
Habitat: Long-tailed Ducks occupy arctic wetlands, tundra, freshwater lakes, ocean coasts, large freshwater lakes, protected bays.
Status and Movements: The Long-tailed Duck is an uncommon winter visitor in Colorado. This distinctive sea duck typically appears on larger bodies of water from late fall, departing by early spring.
Diet: Marine crustaceans, aquatic insects, mussels, small fish, zooplankton, fairy shrimp, fish eggs, plant matter.
Nest: Shallow depression in ground, lined with dwarf willow/birch leaves. Located in clusters on arctic islands/peninsulas.
Breeding: Egg laying: late May-early Jul | Clutch: 6-9 eggs | Broods: 1 | Eggs: Pale gray to olive | Incubation: 24-29 days
Lifespan: At least 17 years.
Population: Global breeding population estimated at 3.2 million individuals.

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Bufflehead (Bucephala albeola)

Identification: Drake: White body, black back, glossy green/purple head, large white patch. Hen/immature: gray-brown, oval white cheek patch.
Compare: Drake Hooded Mergansers have cinnamon (not white) sides and a longer, thinner bill than Drake Buffleheads. The hen Bufflehead has a dark round head and single white patch on the cheek.
Behavior: The Bufflehead dives underwater for aquatic invertebrates. Monogamous; pairs often last several years. Males rapidly bob heads courting hens.
Flocking: Buffleheads are typically found in small, scattered groups or pairs, rarely forming large flocks. Their flight is remarkably fast and erratic, characterized by rapid, whirring wingbeats and sudden, darting movements, especially when flushed.
Habitat: Buffleheads occupy boreal forests, aspen parkland lakes/ponds. Winter: shallow saltwater bays, estuaries, large lakes, inland ponds.
Range: Breeds Canada/Alaska boreal forest; isolated western U.S. populations. Winters coasts/large inland waters across southern North America.
Status and Movements: The Bufflehead is a common winter resident across Colorado. This small diving duck arrives in late fall, gracing open waters until early spring’s departure.
Diet: Aquatic invertebrates, shrimp, crabs, mussels, fish eggs, small fish. Plant seeds (pondweeds/bulrushes).
Nest: Nests exclusively in tree cavities, primarily old Northern Flicker holes. Female lines cavity with down.
Breeding: Egg laying: late Apr-mid-Jul | Clutch: 4-17 eggs | Eggs: Cream-colored or buff; unmarked.
Lifespan: At least 18 years, 8 months.
Population: Global breeding population estimated at 1.3 million individuals.

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Common Goldeneye (Bucephala clangula)

Identification: Drake: Green-black head, round white spot, radiant amber eye, crisp black/white body/wings. Hen: Chocolate head, bright eye, gray body.
Compare: Barrow’s Goldeneyes have an oval or crescent-shaped white spot behind the bill whereas the spot on Drake Common Goldeneyes is round. Barrow’s also have a black spur on the side that Common Goldeneyes lack. Learn the subtle field marks to distinguish the Common Goldeneye from the Barrow’s Goldeneye.
Behavior: Diving duck. The Common Goldeneye forages in flocks that often perform synchronized dives. Drakes display (head backward/forward) courting females.
Flocking: Forms small, loose flocks or linear formations, flying with strong, direct, and swift movements. Their rapid, whirring wingbeats propel them quickly across the water, often in cohesive, though not dense, groups of a few dozen.
Habitat: Boreal forest, tree cavities, lakes, rivers, wetlands. Winter: Protected coastal waters, large inland lakes.
Range: Breeds Canada/Alaska boreal forest, some US states. Winters Atlantic, Pacific, Gulf coasts, large inland waters.
Status and Movements: The Common Goldeneye is a common winter resident throughout Colorado. Arriving in late fall, these striking diving ducks frequent open water, departing as spring approaches.
Diet: Aquatic invertebrates. Vegetation: seeds/tubers (pondweeds, bulrush).
Nest: The Common Goldeneye nests in tree cavities (natural/woodpecker holes) or nest boxes. Female lines cavity/bowl with down feathers.
Breeding: Egg laying: early Apr-mid-Jul | Clutch: 4-9 eggs | Broods: 1 | Eggs: Greenish to olive-green | Incubation: 27-33 days.
Lifespan: At least 20 years, 5 months.
Population: Global breeding population estimated at 2.5 million individuals.

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Barrow’s Goldeneye (Bucephala islandica)

Identification: Male: black/white, purplish head, long white crescent face, white shoulder “windows,” bright yellow eye. Female: cool gray, coppery head, mostly yellow bill.
Compare: Barrow’s Goldeneyes have an oval or crescent-shaped white spot behind the bill whereas the spot on Drake Common Goldeneyes is round. Barrow’s also have a black spur on the side that Common Goldeneyes lack. Learn the subtle field marks to distinguish the Common Goldeneye from the Barrow’s Goldeneye.
Behavior: Active diver, forages on invertebrate prey. Flight swift, rapid wingbeats. Males perform acrobatic courtship displays around females in winter/spring.
Flocking: Flocks during winter on coasts/large lakes. Often remains out of sight of land.
Habitat: Shallow freshwater lakes, mountain ponds, sloughs, remote boreal/montane forests. Winters: rocky marine coastlines.
Range: Breeds western North America mountains/forests (Canada/Alaska). Winters, rocky coasts, large inland lakes.
Status and Movements: The Barrow’s Goldeneye is an uncommon winter resident and local breeder in Colorado. Found primarily in mountainous regions, they are present from fall through spring, with some remaining year-round.
Nest: Nests in tree cavities (old woodpecker holes) or nest boxes. Female uses wood shavings.
Breeding: Egg laying: early Apr-mid-Jul | Clutch: 6-12 | Broods: 1 | Eggs: bluish green to olive-green eggs | Incubation: 29-31 days
Lifespan: At least 18 years.
Population: Global population estimate for Barrow’s Goldeneye not available. Body Measurements: Length: 18.0 in (45.7 cm) Weight: 33.6 oz (950.5 g) Wingspan: 28.2 in (71.35 cm) This Barrow’s Goldeneye data uses averages calculated from the ranges provided.

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Subgroup: Mergansers (Sawbill Ducks)

The Mergansers are easily distinguished by their thin, streamlined bills that are serrated, or “saw-toothed,” which gives them their nickname, “Sawbill Ducks.” This specialized bill is an adaptation for their nearly exclusive diet of fish. While they are powerful divers like the rest of the group, Mergansers in Colorado can be found in a variety of habitats, from freshwater lakes and rivers (Hooded Merganser) to saltwater estuaries (Red-breasted Merganser).

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Hooded Merganser (Lophodytes cucullatus)

Identification: Drake: black/white patterns, chestnut flanks, large white patch on black, fan-shaped crest. Hen/immature: gray/brown with tawny-cinnamon crest.
Compare: Drake Buffleheads have a white belly and sides whereas Drake Hooded Mergansers have cinnamon sides and a longer and thinner bill. Buffleheads are smaller. Hens Hooded Merganser are darker and smaller than hens Red-breasted and Common Mergansers.
Behavior: Busy diver. Drakes court expanding crests, making low, groaning calls. Not known if pairs reunite post-incubation. Runs across water to fly.
Flocking: Hooded Mergansers typically fly in small, often single-file groups, rarely forming large congregations. They exhibit very fast, direct flight with rapid, shallow wingbeats, displaying surprising agility as they navigate waterways with heads held low.
Habitat: Forested wetlands, small ponds, rivers, lakes, marshes, protected saltwater bays.
Range: Breeds eastern half/Pacific Northwest North America. Winters large fresh/brackish bays, US inland waters.
Status and Movements: The Hooded Merganser is an uncommon winter resident and local breeder in Colorado. These distinctive ducks are present from fall through spring, with some pairs nesting in forested wetlands.
Diet: Small fish, aquatic insects, crustaceans, amphibians, mollusks, vegetation.
Nest: Tree cavity (live/dead tree, 10–90 feet high) or nest box. Female adds down to shallow bowl in cavity.
Breeding: Egg laying: Feb-early May | Clutch: 5-13 eggs | Broods: 1 brood | Eggs: White, thick shelled | Incubation: 26-41 days
Lifespan: At least 14 years, 6 months.
Population: Estimated at 1.1 million individuals.

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Red-breasted Merganser (Mergus serrator)

Identification: Drake: dark green shaggy crest, red bill/eye, rusty chest, white neck band. Hen/nonbreeding male: brownish gray, brown shaggy head.
Compare: Breeding Drake Common Mergansers have white sides and a white breast whereas Drake Red-breasted Mergansers have gray sides and a cinnamon breast. Hen/nonbreeding male Common Merganser have a neat head/neck border colors; these colors blend into each other in Red-breasted Merganser. Learn the subtle field marks to distinguish the Female Common Merganser from the Female Red-breasted Merganser.
Behavior: Dives underwater capturing prey with serrated bill. Non-territorial, social. Sits low in water. Requires running start to become airborne.
Flocking: The Red-breasted Merganser often flies in small, loose flocks or irregular lines, demonstrating strong, direct flight close to the water. Their flight is rapid and powerful, with quick wingbeats.
Habitat: Boreal forest, fresh/brackish/saltwater wetlands (breeding). Oceans, lakes, rivers, estuaries, bays (winter).
Range: Breeds boreal forest, typically near coast. Winters US coastal waters, Mexico, large inland lakes.
Status and Movements: The Red-breasted Merganser is an uncommon transient and winter visitor in Colorado. This slender diving duck is most often seen during migration, from late fall to early spring, on larger waters.
Diet: Small fish (4–6 inches long), crustaceans, insects, tadpoles.
Nest: Depression on ground under dense cover (logs/boulders/branches). Lined with dead grasses, insulating down feathers. Nests alone or in colonies.
Breeding: Egg laying: mid-May – mid-Jul | Clutch: 3-24 eggs | Broods: 1 brood | Eggs: Olive-buff | Incubation: 28-35 days.
Lifespan: At least 9 years, 6 months.
Population: Estimated at 370,000 individuals.

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Common Merganser (Mergus merganser)

Identification: Breeding Drake: gleaming white body, dark iridescent-green head, slender red bill. Hen: gray body, rusty-cinnamon head, short crest. Males wear nonbreeding plumage (late summer to mid-autumn) similar to female.
Compare: Breeding Drake Common Mergansers have white sides and a white breast whereas Drake Red-breasted Mergansers have gray sides and a cinnamon breast. Hen Common Merganser have a neat border (blended in Red-breasted) between cinnamon head and pale neck/breast. Learn the subtle field marks to distinguish the Female Common Merganser from the Female Red-breasted Merganser.
Behavior: Dive underwater to catch fish. Hen cares for chicks; Drakes gather in large flocks. Foraging: probe sediments/stones with serrated bill.
Flocking: Forms large flocks in winter on large inland reservoirs/rivers. Flocks may include other diving ducks (Bufflehead, goldeneyes). Up to 75 individuals.
Habitat: Northern forested habitats, large lakes, rivers. Winter: large lakes, rivers, reservoirs, coastal bays, estuaries.
Range: Breeds northern North America rivers/lakes. Winters southern/coastal regions, US states. The Common Merganser is widespread.
Status and Movements: The Common Merganser is a common resident and winter resident in Colorado. Found on various water bodies, they are present year-round, with increased numbers during the colder months.
Movements: Winters on large lakes/rivers, moving to coasts/southern regions of range.
Diet: Fish, aquatic invertebrates (insects, mollusks, crustaceans, worms), frogs, small mammals, birds, plants.
Nest: Tree cavity (natural or woodpecker hole) or nest box. Hen uses wood chips/shavings, lines with breast down.
Breeding: Egg laying: mid Apr-early Aug | Clutch: 6-17 eggs | Broods: 1 | Eggs: White, creamy, or ivory yellow | Incubation: 28-35 days.
Lifespan: At least 13 years, 5 months.
Population: Global breeding population estimated at 1.9 million individuals.

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Subgroup: Stiff-Tailed Ducks

The Stiff-Tailed Ducks are a small, distinctive group named for their unique, rigid tail feathers that are often held upright like a sail when the birds are at rest or displaying. These ducks are highly aquatic and arguably the most specialized diving ducks in North America.

They have compact bodies, thick necks, and legs positioned so far back that they are nearly incapable of walking on land. Consequently, they spend almost their entire lives on the water, where they dive frequently and expertly propel themselves using their large feet. In Colorado, the group is represented almost exclusively by the Ruddy Duck, a relatively common winter visitor. The second species in this group, the tropical Masked Duck, an extremely rare and accidental visitor to the state.

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Ruddy Duck (Oxyura jamaicensis)

Identification: Drake summer: chestnut body, sky-blue bill, white cheek, black cap. Winter male/Hen: dull gray-brown, blurry cheek stripe. Compact, stiff tail often held upright.
Compare: Hen Black Scoters are larger and do not hold their tail upwards like Ruddy Ducks do. Hen Buffleheads are smaller.
Behavior: Dive for aquatic invertebrates. Forages mostly nocturnally. Highly aggressive, often fight others. Courtship: bill striking neck creates water bubbles.
Flocking: The Ruddy Duck is a reluctant flyer, typically seen alone or in small groups. When aloft, it flies low over water with rapid, stiff wingbeats in a direct path, preferring to dive when disturbed.
Habitat: Marshes, reservoirs, large lakes, prairie potholes, brackish bays, coastal estuaries, ponds.
Range: Breeds prairie pothole region/western US. Winters in the southern US, extending through Mexico to Central America.
Status and Movements: The Ruddy Duck is a common resident and migrant in Colorado. These stiff-tailed ducks are present year-round, with breeding populations in summer and augmented numbers during migration.
Diet: Midge larvae, aquatic insects, crustaceans, zooplankton, worms, snails. Aquatic plants (pondweed, bulrushes), seeds.
Nest: Dry plant materials platform becomes bowl-like. Female weaves vegetation canopy over nest. Built 2–10 inches over water in cattails.
Breeding: Egg laying: N/A | Clutch: 3-13 eggs | Broods: 1-2 | Eggs: White/yellowish white, pebbly | Incubation: 20-26 days.
Lifespan: At least 13 years, 7 months.
Population: Global breeding population estimated at 1.3 million individuals.

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GEESE OF COLORADO

Geese are easily distinguished from ducks by their larger size, longer necks, and more upright posture. Unlike ducks, geese are primarily grazers, spending much of their feeding time on land, eating grass and other short vegetation. They also form strong, lasting pair bonds and travel in tight-knit family units, giving them a much different social structure than most ducks.

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Canada Goose (Branta canadensis)

Identification: Black head, white cheeks/chinstrap, black neck, brown back. Adults: tan breast.
Compare: Cackling Geese are smaller with a smaller bill and a shorter neck than Canada Goose. Cackling Geese also have a blockier head and steeper forehead than Canada Geese. Learn the subtle field marks to distinguish the Cackling Goose from the Canada Goose.
Behavior: Dabbling in water or grazing fields/lawns. Mate for life, pairs remain together year-round. Highly social; defend territory aggressively during breeding.
Flocking: The Canada Goose is highly gregarious, flying in large, organized V-formations or wavy lines with powerful, rhythmic wingbeats. Their flight is strong and purposeful, covering vast distances during migration at a steady pace.
Habitat: Lakes, rivers, ponds, marshes, yards, park lawns, farm fields, airports, golf courses.
Range: Widespread North American distribution. Migrates north/south; increasing resident populations in urban/suburban areas. The Canada Goose is common and widespread.
Status and Movements: The Canada Goose is an abundant resident and winter resident across Colorado. These iconic geese are present year-round, with large migratory flocks augmenting local populations during colder months.
Diet: Grasses, sedges, eelgrass, berries, seeds, agricultural grains (corn, wheat).
Nest: Large open cup on ground. Dry grasses, mosses, lichens, plant material. Lined with down/body feathers. Elevated site near water.
Breeding: Egg laying: Apr-mid-May | Clutch: 2-8 eggs | Broods: 1 brood | Eggs: Creamy white | Incubation: 25-28 days.
Lifespan: At least 33 years, 3 months.
Population: Population estimated at 7.1 million individuals.

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Cackling Goose (Branta hutchinsii)

Identification: Small, short-necked, round head, stubby-billed goose. Size and shape are best identification clues. Four subspecies involved.
Compare: Usually very similar in plumage to Canada Goose, but some Cackling have a more prominent white neck collar. Some are only slightly larger than a Mallard while some can be only slightly smaller than a Canada Goose. Learn the subtle field marks to distinguish the Cackling Goose from the Canada Goose.
Behavior: Dabbling in water or grazing fields/lawns. Pairs remain together year-round. Highly social.
Flocking: Associate in large flocks. Flocks assume V formation in flight. Flights involve loose family aggregations.
Habitat: Grassy field, rivers, ponds, marshes, yards, park lawns, farm fields.
Range: Each subspecies breed in separate regions of the far north in Canada and Alaska. Increasing resident populations in urban/suburban areas.
Status and Movements: The Cackling Goose is a common winter resident and transient in Colorado. These smaller geese arrive in fall, remaining through winter, and depart with the onset of spring migration.
Diet: Grasses, sedges, eelgrass, berries, seeds, agricultural grains.
Nest: Large open cup on ground. Dry grasses, mosses, lichens, plant material. Lined with down/body feathers.
Breeding: Egg laying: mid May-mid-July | Clutch: 2-8 eggs | Broods: 1 brood | Eggs: Creamy white | Incubation: 25-28 days.
Lifespan: At least 22 years, 8 months.
Population: Population estimated at 7.1 million individuals.

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Snow Goose (Anser caerulescens)

Identification: White body, black wingtips visible in flight. Pink bill has dark “grinning patch.” Dark morph (“Blue Goose”): white face, dark brown body. Juveniles slightly smaller/grayer.
Compare: Ross’s Goose is smaller with a much smaller bill than Snow Goose. Lacks Snow Goose’s black line or “grinning patch” on bill. Learn the subtle field marks to distinguish the Snow Goose from the Ross’s Goose.
Behavior: Forages digging up roots/tubers (muddy areas) or grazing. Highly social, forms immense flocks. Females incubate; males guard.
Flocking: The Snow Goose forms immense, often chaotic, flocks numbering in the thousands. Their flight is strong and erratic, often appearing as undulating masses or loose V-formations, creating a cacophony as they move purposefully.
Habitat: Arctic tundra, ponds, shallow lakes, coastal salt marshes, streams, agricultural fields, wetlands, grasslands, marine inlets.
Range: Breeds Canadian/Alaskan Arctic tundra. Winters US/Mexico coasts, inland areas, agricultural fields.
Status and Movements: The Snow Goose is a common winter resident and transient in Colorado. Large flocks arrive in fall, spending the winter in agricultural fields and wetlands before departing in spring.
Diet: Grasses, sedges, rushes, forbs, horsetails, shrubs, willows, roots, tubers, seeds, agricultural grains.
Nest: Female builds simple scrape, adds down, plant material (sea-lyme grass, eelgrass, willow, birch, seaweed).
Breeding: Egg laying: late May-early Jul | Clutch: 2-6 eggs | Broods: 1 brood | Eggs: Creamy white (staining dirty gray) | Incubation: 24 days.
Lifespan: At least 30 years, 8 months.
Population: Estimated at 16 million individuals.

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Ross’s Goose (Anser rossii)

Identification: Adults white, black wingtips, pink bill, no or little “grin patch”. Rare dark (“blue”) morphs exist. Immatures white, tinged gray, dark bill.
Compare: Snow Goose is larger with a larger bill and obvious grin patch. Learn the subtle field marks to distinguish the Snow Goose from the Ross’s Goose.
Habitat: Low arctic tundra, islands (nesting/breeding). Wetlands, meadows, agricultural fields, lakes, reservoirs (migration/winter).
Range: Breeds Low Arctic tundra (Canada). Winters California, New Mexico, Texas, Louisiana, mixing with other geese.
Status and Movements: The Ross’s Goose is a common winter resident and transient in Colorado. Often found with Snow Geese, these smaller white geese arrive in fall and depart by early spring.
Diet: Plant matter: grasses, sedges, wild and domestic grains. Rarely digs roots/tubers like Snow Goose.
Nest: Large, soft bowl/depression on raised tundra, often island colonies. Grass, willow, moss, down-lined.
Breeding: Egg laying: Jun-late-Jul | Clutch: 2-6 eggs | Broods: 1 brood | Eggs: White, usually stained | Incubation: 19-25 days.
Lifespan: At least 22 years, 6 months.
Population: Estimated at 1.7 million individuals. The Ross’s Goose population was historically low but increased steeply due to climate change reducing snow cover.

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Greater White-fronted Goose (Anser albifrons)

Identification: Adults brown, white around the base of pinkish-orange bill, black belly barring, dark tail forms a “U” with upper/undertail coverts. Juveniles lack belly barring/white face feathers.
Compare: Canada Goose neck and head are black. Greater White-fronted Goose has the bill and legs pink-orange.
Behavior: Forages fields/lakes in groups. First to flush when disturbed. Forms long-term pair bonds, stay together year-round.
Flocking: The Greater White-fronted Goose gathers in moderate to large flocks, migrating in less rigid V-formations or undulating lines. Their flight is strong and direct, with deliberate wingbeats, maintaining a consistent speed over long distances.
Habitat: Tundra wetlands, rivers, ponds, sedge meadows, tidal mudflats, agricultural fields, lakes, marshes.
Range: Breeds tundra. Migrates/winters mainly west of Mississippi, California, Texas, Louisiana.
Status and Movements: The Greater White-fronted Goose is a common transient and winter resident in Colorado. Migrating through in fall and spring, many remain through winter, favoring agricultural areas.
Diet: Sedges, grasses, berries, plant tubers (summer). Seeds, grain, grasses (winter).
Nest: Scrape in ground, densely covered by grass/sedge/dwarf shrubs near water/upland tundra. Lined with plant material/down.
Breeding: Egg laying: late May-early Jul | Clutch: 1-8 eggs | Broods: 1 brood | Eggs: White to tan, stained | Incubation: 22-27 days.
Lifespan: At least 25 years, 6 months.
Population: Estimated at 2.1 million individuals.

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SWANS OF COLORADO

Swans are the largest species of waterfowl, easily distinguished from both ducks and geese by their truly massive size, pure white plumage, and exceptionally long necks. They are perhaps the most elegant of all water birds, known for their signature “S” curve of their necks when swimming. Unlike native swans, which are migratory, the introduced Mute Swan is primarily an ornamental species, often found on private and public ponds throughout Colorado.

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Tundra Swan (Cygnus columbianus)

Identification: Entirely white plumage, black bill, usually yellow spot near the eye. Neck straight. Immature gray-tinged on wings/head/neck.
Compare: Most Trundra Swans have a yellow spot near the eye in contrast to an all-black bill of the Trumpeter Swan, which is larger in size. The border separating the bill and forehead is “V” shaped in Trumpeter Swan and more “U” shaped in Tundra Swan. Learn the subtle field marks to distinguish the Trumpeter Swan from the Tundra Swan.
Behavior: Form lifelong pairs, feed/roost together year-round. Tip up for submerged vegetation. Pairs defend territory.
Flocking: Forms large, gregarious flocks when not breeding. Fly with necks outstretched; wings make characteristic whistling sound. Flocks forage/roost together.
Habitat: Arctic tundra, river deltas, pools, lakes, ponds, estuaries, coastal waters, agricultural fields.
Range: Nests Arctic tundra (Alaska/Canada). Winters US coastal/inland waters.
Status and Movements: The Tundra Swan is an uncommon transient and winter visitor in Colorado. These elegant swans are seen primarily during fall and spring migration, with fewer overwintering on open waters.
Diet: Plant matter, tubers, stems, leaves, seeds, pondweed, sedges, algae, mollusks, arthropods, agricultural grains (corn/soybeans/rice).
Nest: Mound of vegetation (grasses/sedges/lichens). Built on island or elevated tundra ridge near large water body.
Breeding: Egg laying: May-mid-Jul | Clutch: 3-5 eggs | Broods: 1 brood | Eggs: Creamy white, stained tan | Incubation: 31-32 days.
Lifespan: At least 23 years, 7 months.
Population: Population estimated at 280,000 individuals.

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Trumpeter Swan (Cygnus buccinator)

Identification: Adults entirely snowy white, black bill, black legs. Immatures gray-brown. Largest waterfowl species in North America.
Compare: Most Trundra Swans have a yellow spot near the eye in contrast to an all-black bill of the Trumpeter Swan, which is larger in size. The border separating the bill and forehead is “V” shaped in Trumpeter Swan and more “U” shaped in Tundra Swan. Learn the subtle field marks to distinguish the Trumpeter Swan from the Tundra Swan.
Behavior: Trumpeter swans forage in shallow water, tips up for aquatic vegetation. Form lifelong pair bonds; pairs stay together year-round.
Flocking: Travels in pairs/family groups. Flocks fly lower than other swans/ducks. Needs 100-yard open water “runway” for takeoff.
Habitat: Shallow freshwater ponds, lakes, marshes, rivers. Winter: ice-free streams, estuaries, reservoirs.
Range: Breeds Alaska, Canada, northwestern US, Midwest/Great Lakes. Winters ice-free coastal/inland waters.
Status and Movements: The Trumpeter Swan is a rare transient and winter visitor in Colorado. The largest North American waterfowl, it is occasionally observed on large, open water bodies during migration or winter.
Diet: Aquatic plants (pondweeds, wild rice, duckweed). Terrestrial plants, berries, grain crops (corn, barley).
Nest: Mound built on muskrat/beaver dens, islands, or manmade platforms. Foundation of aquatic vegetation.
Breeding: Egg laying: late Apr-late Jul | Clutch: 4-6 eggs | Broods: 1 brood | Eggs: Creamy to dull white, often stained brown | Incubation: 32-37 days.
Lifespan: At least 26 years, 2 months.
Population: Estimated at 63,000 individuals. The Trumpeter Swan population is recovering.

Mute Swan (Cygnus olor)

Identification: Entirely white plumage. Orange bill with a black base/knob (knob swells in breeding male). Neck usually curved into an S. Juveniles dusky gray-brown.
Compare: Tundra Swans are smaller than Mute Swans with a black (not orange) bill. They often hold their neck straighter than Mute Swans.
Behavior: Swims with wings slightly raised. Feeds grazing underwater vegetation, raking bottom with feet. Extremely aggressive, attacks intruders.
Flocking: The Mute Swan often flies in pairs or small family groups, sometimes forming larger winter flocks. Their powerful, direct flight features slow, deep wingbeats producing a characteristic humming sound, moving steadily in loose lines.
Habitat: Urban lakes, farm ponds, rivers, estuaries, bogs, creeks, streams, embayments.
Range: Nonnative. Established in the Northeast, Midatlantic, Great Lakes, Pacific Northwest US. The Mute Swan is widespread across these areas.
Status and Movements: The Mute Swan is a localized, non-native resident in Colorado. Established populations, often associated with parks and urban ponds, are present year-round, not exhibiting migratory patterns.
Diet: Aquatic vegetation (eelgrass, pondweeds, algae, flowering grasses, grains), frogs, tadpoles, fish, snails, mollusks, insects.
Nest: Large platform of vegetation (twigs, reeds, grasses). Built on peninsula/shoreline/island. Lined with grass/down.
Breeding: Egg laying: late Mar-early May | Clutch: 2-5 eggs | Broods: 1 brood | Eggs: Blue-green (changes to white/chalky) | Incubation: 34-41 days
Lifespan: At least 26 years, 9 months.
Population: Global population estimated at 400,000 individuals.

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The Urban Mix: Feral and Domestic Waterfowl of Colorado

In Colorado’s parks, retention ponds, and urban lakes, birders and casual observers often encounter waterfowl that do not fit the description of wild, native species. This group, labeled Feral and Domestic Waterfowl of Colorado, consists of birds that have either escaped captivity, been intentionally released, or are descendants of those birds.

Identification Challenges

The presence of domestic stock, particularly the Mallard and the non-native Muscovy Duck, leads to two major identification hurdles:

1. Variable Plumage: Domestic birds, descended from wild stock, have been bred for varied colors (white, black, crested, etc.). These individuals often show exaggerated features or color patterns never found in wild populations.
2. Hybridization: Domestic birds readily interbreed with wild counterparts and with other domestic strains, resulting in a large number of hybrids. These birds often exhibit a confusing mix of physical traits that makes tracing their parent species virtually impossible.

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Feral Muscovy (Cairina moschata): Large, long-bodied duck with a carunculated (red, warty) face mask. Plumage is highly variable (black, white, piebald) but retains the large white wing patch.
Pekin Duck (Domestic Mallard): Large and heavy, entirely white body; bright yellow-orange bill and legs.
Rouen Duck (Domestic Mallard): Very large and heavy version of the Mallard; often has the same rich brown and green plumage.
Hybrid Mallards: Exhibits a confusing mix of traits. Look for: Patches of pure white on a normally-colored duck; a green head with a speckled or streaked breast; or odd bill/leg colors.
Crested Duck (Domestic Mallard): Any color (often white, piebald, or mottled) but defined by a distinct puff of feathers on the top of the head.
Chinese Goose (Anser cygnoides domesticus): Recognized by the distinctive large, raised knob or ‘knob-bill’ at the base of the forehead, just above the bill. Usually white or brown/gray, with a long, slender neck.
Graylag (Barnyard) Goose (Anser anser): Large, bulky gray or white goose with thick neck, stout legs, and a prominent orange or pink bill. Often appears very heavy-bodied and flightless.
Egyptian Goose (Alopochen aegyptiaca): Large, goose-like bird with pink legs/bill and a conspicuous dark brown eye patch (goggles). The body is beige, gray, and brown with a unique white-and-black wing pattern visible in flight.

The most confusing identification issues in Colorado’s urban environments stem from non-native species like the Feral Muscovy Duck and the various domestic Mallard hybrids. The image above features the nine most common non-native species you may encounter in Colorado’s city parks, retention ponds, and suburban waterways. These non-native ducks and geese are the primary cause of ID confusion in the State.

For a complete North American guide covering the lineage, identification keys of these confusing domestic and invasive species, please consult our in-depth article: Beyond the Mallard: A North American Guide to Urban Ducks, Geese, and Hybrids.

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Colorado Waterfowl Hotspots: Top 5 Locations for Viewing

Colorado’s diverse aquatic habitats support substantial concentrations of ducks, geese, and swans. These varied ecosystems ranging from alpine lakes to prairie marshes offer essential refuge for migratory species along the Central Flyway.

Monte Vista National Wildlife Refuge: Located in the San Luis Valley, this refuge features extensive wetlands and managed grain fields. It provides vital habitat for thousands of migrating birds. You can reliably spot Northern Pintails, Mallards, and Cinnamon Teal among the vast flocks during peak migration seasons.

Barr Lake State Park: Situated northeast of Denver, this expansive prairie reservoir is surrounded by cottonwood groves. It serves as a premier destination for watching wintering waterfowl. Visitors frequently observe Wood Ducks, Hooded Mergansers, and Canada Geese across its calm waters.

Arapaho National Wildlife Refuge: Nestled in the high-altitude glacial basin of North Park, this refuge offers unique riparian habitats. It is a critical breeding ground for many species. Look for Gadwalls, American Wigeons, and Canvasbacks throughout the diverse marsh complexes.

John Martin Reservoir State Park: Located in Bent County, this massive reservoir on the Arkansas River attracts huge wintering populations. The open water and surrounding fields are perfect for viewing. High-value species here include Snow Geese, Ross’s Geese, and Common Goldeneyes.

Fossil Creek Reservoir Natural Area: Situated near Fort Collins, this natural area features a large, protected reservoir that serves as a sanctuary. It is particularly known for rare winter visitors. Keep an eye out for Tundra Swans, Buffleheads, and Redheads along the quiet shorelines.

Waterfowl of Conservation Concern and Decline in Colorado

Recent assessments indicate a precipitous collapse in grassland-obligate waterfowl populations throughout the Central Flyway, signaling an ecological crisis.

Red Alert “Tipping Point” Species

Northern Pintail: Designated a “Tipping Point” species in the 2022 State of the Birds report, this species has suffered a cumulative population loss exceeding 70% since 1966. Current trajectories suggest the loss of an additional 50% of the remaining population within decades without immediate habitat remediation.

Key Threats to Waterfowl Populations

Anthropogenic pressures and biological stressors severely compromise regional waterfowl viability.

1. Habitat Loss and Degradation: The systemic drainage and agricultural conversion of shallow seasonal wetlands and playa lakes in Eastern Colorado have eliminated critical stopover and breeding resources essential for Northern Pintail recovery, severing vital connectivity within the flyway.
2. Biological and Ecological Threats: Genetic introgression poses a severe risk to the Mexican Duck in the San Luis Valley; extensive hybridization with ubiquitous Mallards threatens to swamp the unique genetic integrity of this recently recognized, range-restricted species.

Read more about the Conservation Status of North American Ducks, Geese, and Swans.

Conclusion:

This guide provide the tools to navigate the diverse world of Colorado waterfowl. It provides the foundation for confident identification, covering native, migrants, and addressing confusing urban species. We encourage you to use the information provided here as you explore the state.

Photo Credits:

The photographic material used in this guide was made available on various websites. Many thanks to Andrew Morffew, Mark Mochell, Elizabeth Milson, Emily Chen, Dennis Church, Wendy Miller, Ken Slade, John Benson, Mick Thompson, Steve Guttman, Nicole Beaulac, Andy Reago, Chrissy McLaren, Garry C., Shawn Taylor, Steve Kersting, Gary Leaven, Vicky DeLoach, Don Hoechlin, Tom Murray, Kevin Krebs, Deborah Freeman, Kenneth Cole-Schneider, Doug Greenberg, Ian Preston, Brian Garrett, John Strung, Becky Matsubara, Judy Gallagher, Bob Jensen, Veit, Sand Diego Zoo, David Inman, Dan Mooney, Ian Preston, Lloyd Davis, Denis Fournier, Gregory Heaton, Greg Lavaty, Dona Hilkey, Alain Doyle, Aaron Maizlish, Ashley Tubs, Richard George, Ethan Gosnell, Nick, , Steve Valasek, Mitch Walters, , and Julio Mulero.

Voices:

Most recordings were obtain from: (Xeno-canto https://xeno-canto.org/)

References and Sources:

• Allaboutbirds.org
• eBird. (https://ebird.org/)
• Birds of the World: https://birdsoftheworld.org/bow/home
• Gill, Frank B., 1994. Ornithology – 2nd Edition, W. H. Freeman and Company.
• Sibley, David, 2000, The Sibley Guide to Birds. Alfred A. Knopf, Publisher.
• Species Longevity Data: United States Geological Survey (https://www.usgs.gov/)
• The Sibley Guide to Bird Life and Behavior, 2001. Chris Elphick, John Dunning, and David Sibley (eds). Alfred A. Knopf, New York.

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