Greater Scaup: Habitat, Diet, Behavior & Conservation Facts (2026)

This site is supported by our readers. We may earn a commission, at no cost to you, if you purchase through links.

When waterfowl populations shift across continents, few species draw as much concern from conservationists as the greater scaup. This medium-sized diving duck has seen its numbers plummet over recent decades, even as it continues its ancient migration routes between Arctic breeding grounds and temperate coastal waters.

You’ll recognize these birds by their rounded heads and distinctive pale blue bills—features that set them apart from their close relatives. Males sport striking black-and-gray plumage, while females wear more subdued brown tones.

Understanding what drives their decline matters because these ducks serve as indicators of broader wetland health across two continents.

What is The Greater Scaup?

The Greater Scaup is a circumpolar diving duck that breeds across the Arctic tundra regions of North America and Europe.

Like the closely related spectacled eider, scaups are exceptional divers that can descend to impressive depths while foraging for aquatic invertebrates.

You’ll recognize this medium-sized waterfowl by its distinctive rounded head and pale blue bill. To properly identify this species in the field, you need to understand its scientific classification, physical characteristics, and key field marks.

Scientific Classification

You’re looking at a diving duck with a precise spot in the taxonomic system.

The greater scaup belongs to kingdom Animalia, phylum Chordata, and class Aves. Within order Anseriformes and family Anatidae, it sits in genus Aythya as species marila.

Phylogenetic analysis shows it’s closely related to the lesser scaup, with the tufted duck next in line—evolutionary history shaped by circumpolar habitats.

For detailed insight into its distribution and conservation status, see recent studies.

Physical Description

You’ll notice the greater scaup‘s compact body shape right away—males sport a black breast and head with a medium gray back, while females wear brown plumage with lighter edges.

Both sexes have a broad, pale blue beak structure ideal for filter feeding. The yellow eye stands out against darker feathers, and adults measure 39 to 43 centimeters in length with wingspans around 66 to 78 centimeters.

Identification Features

You can distinguish greater scaup (Aythya marila) from similar species by examining head shape—look for a rounded, peaked crown. Males display glossy green heads in breeding plumage, while females show pale gray faces with darker crowns.

Bill structure matters too: the pale blue-gray beak is broader than lesser scaup’s. Plumage variations include white flanks on males and mottled brown feather patterns on females.

Greater Scaup Habitat and Range

You’ll find Greater Scaup across a vast range that stretches from the Arctic to temperate coasts. These diving ducks don’t stay put—they shift between breeding grounds, wintering spots, and migration corridors throughout the year.

Understanding where they go and why helps you appreciate how they’ve adapted to life in both freshwater and saltwater environments.

Breeding Grounds

You’ll find greater scaup nesting in shallow freshwater lakes and wetlands across Alaska, western Canada, and the northern U.S. boreal region. These breeding grounds offer the perfect stage for raising chicks.

During the breeding season, males perform distinctive head bobbing courtship displays to attract females and establish pair bonds in these northern wetlands.

• Nest sites sit within 1–3 kilometers of feeding wetlands in cattail and bulrush marshes
• Water depths range from 0.5 to 2 meters with abundant invertebrate prey
• Females select locations near water edges with emergent vegetation for predator cover
• Ice-out in spring triggers rapid courtship and nesting activity across the tundra

The greater scaup’s choice of habitat is a classic example of how animals utilize specific breeding ground environments to guarantee reproductive success.

Wintering Locations

During the coldest months, you’ll encounter massive winter flocking concentrations along coastal migration routes stretching from the Gulf of Mexico to the Atlantic seaboard. These coasts and shorelines provide critical winter habitat where scaup exploit tidal feeding opportunities in estuary habitats.

Wintering Region	Habitat Type	Key Features
Gulf of Mexico	Brackish lagoons	Stable prey availability
Atlantic Coast	Shallow bays	Ice-free feeding patches
Great Lakes	Freshwater wetlands	Mixed waterfowl congregations
St. Lawrence Estuary	Coastal marshes	Marine conservation priorities

Mild temperatures and abundant mollusks make these sites essential for survival.

Migration Patterns

As autumn shifts the landscape, you’ll witness these divers set out on notable journeys along established flyways. Migration timing starts in September and peaks through October, with spring return from February to April.

Route selection and stopover ecology determine survival success during these avian migration patterns.

Behavior and Feeding Habits

Greater Scaup are skilled divers that spend much of their day underwater searching for food.

Their feeding habits change with the seasons and tides, adapting to what’s available in their environment. Understanding how these ducks hunt and interact in groups gives you insight into their survival strategies.

Foraging Techniques

You’ll notice Greater Scaup use specialized foraging strategies to reach prey both underwater and at the surface. Diving ducks like these probe soft substrates and filter sediment for hidden invertebrates during submerged grazing. Surface foraging involves dabbling along shorelines where tidal flows concentrate food.

Their feeding behaviors shift with habitat conditions and season.

Foraging Method	Key Technique
Diving Methods	Probe substrate for snails and worms
Submerged Grazing	Filter sediment in shallow water
Surface Foraging	Dabble for insects near water edge
Patch Selection	Assess water clarity before entering

Diet Composition

Your Greater Scaup‘s diet shifts like the seasons themselves, adapting to what’s available beneath the waves. Nutrient balance in Aythya ducks depends on smart prey selection across diverse food sources that fuel energy intake and survival.

• Mollusks like mussels and clams anchor winter feeding habits in coastal bays
• Aquatic insects and larvae supply protein during breeding season
• Plant material provides essential carbohydrates year-round
• Small crustaceans deliver minerals for shell growth and metabolism

Social and Flocking Behavior

You’ll see thousands of these duck species riding currents together, their synchronized movements revealing complex bird behavior at work.

Winter flocks use group vigilance to spot predators while foraging strategies shift as tides change.

Social learning helps younger waterfowl master diving techniques faster.

Migration patterns bring mixed-species groups to coastal bays, where flock dynamics reduce individual risk and boost feeding success across variable conditions.

Breeding and Life Cycle

Greater Scaup are seasonally monogamous, forming new pair bonds each breeding season.

The species nests in Arctic tundra wetlands, where females raise their young in shallow freshwater areas. Understanding their reproductive cycle helps you see how these diving ducks have adapted to life in harsh northern environments.

Mating and Nesting

When breeding season arrives, you’ll see males perform head bobbing and wing spreading to attract females. They bring aquatic prey as courtship offerings that signal their ability to provide.

Pairs bond on nesting sites near shallow water, where females build shallow cup nests using grasses and reeds collected from surrounding marshes. Males defend the territory while females handle most nest construction.

Egg Laying and Development

Once the nest is ready, females usually lay 4 to 9 eggs over several days. Each egg forms in a 24 to 26 hour cycle before being laid. The incubation period lasts about 26 to 28 days, with three key stages you’ll observe:

1. Egg Formation – Shell development takes roughly one day per egg
2. Embryo Growth – Organ systems form within two weeks
3. Hatching – Chicks use an egg tooth to break free

Females handle incubation alone, leaving briefly to feed.

Lifespan and Survival Rates

Once those hatchlings emerge, you’re looking at a journey where about 50 to 60 percent make it through their first year—mortality factors like predation and harsh weather shape age distribution early on.

Adults usually live 6 to 12 years, though survival trends show some reach beyond 15. These longevity patterns matter for population dynamics and wildlife conservation, helping you understand ecological balance in bird species conservation efforts.

Conservation Status and Challenges

The Greater Scaup‘s story isn’t all smooth sailing. Over the past few decades, their numbers have dropped dramatically, and scientists are still piecing together why.

Let’s look at what’s happening with their population, what threatens them, and how researchers are working to turn things around.

Population Trends

Over recent decades, you’ve witnessed a troubling shift: Greater Scaup populations have plummeted from 7 million in the early 1980s to just 4 million today. Waterfowl population surveys reveal this population decline mirrors broader wildlife population trends affecting diving ducks across North America.

Greater Scaup populations have crashed from 7 million in the 1980s to just 4 million today, mirroring broader diving duck declines across North America

• Your favorite coastal bays may hold far fewer flocks than they once did
• Species migration routes now carry diminishing numbers each season
• Wildlife conservation experts still puzzle over the full scope of this decline

Threats and Causes of Decline

So why the drop? Habitat loss from wetland drainage and shoreline development strips away breeding and foraging sites you’d expect scaup to thrive in.

Climate change disrupts migration timing and prey availability. Pollution effects, from heavy metals to pesticides, degrade water quality and food sources.

Disease outbreaks like avian influenza sweep through dense wintering flocks. Human impact through these combined threats challenges wildlife conservation efforts and the species’ conservation status.

Conservation Efforts and Research

Across North America, wildlife conservation efforts now target scaup through coordinated action. You’ll find habitat restoration projects expanding wetlands and improving water quality.

Wildlife monitoring programs track populations using aerial surveys and GPS telemetry. Conservation planning integrates science with management needs. Research initiatives employ remote sensing and AI to predict distribution shifts.

Frequently Asked Questions (FAQs)