Greater Scaup

Fascinating facts about the Greater Scaup

• Every winter, greater scaups gather in flocks of up to 200,000 birds on open water — often the same bays and coastal zones their parents and grandparents used, passed down through generations like a family address written in instinct. They dive 30 feet deep to vacuum mollusks and amphipods off the seafloor, their wings folded tight against their bodies as they work. This fidelity to wintering grounds means a single contaminated bay can impact tens of thousands of birds across the entire population.
• The greater scaup's bill is flattened and spatulate, designed like a biological sieve — as it feeds underwater, water flows out through the edges while tiny crustaceans and mollusk pieces stay trapped inside. Males have iridescent green heads that only flash brilliant in direct sunlight; in overcast light they look almost black, which is why early hunters often mistook them for different species entirely. This optical trick has led to centuries of confusion about their true abundance and range.
• A greater scaup's heart beats roughly 400 times per minute while swimming on the surface — but when it dives, the heartbeat plummets to just 25 beats per minute, a survival trick that conserves oxygen and lets them hunt the dark seafloor for up to 60 seconds at a time. Their spleen contracts during a dive, releasing stored blood cells that boost oxygen capacity. This is the same physiology that lets seals and whales survive in the deep; the scaup uses it to hunt in 30 feet of water.
• In the 1960s and 1970s, greater scaup populations on the Atlantic coast crashed by 50%, a mystery that baffled ornithologists for decades — until researchers discovered lead shot from waterfowl hunting was poisoning them as they fed on the seafloor, ingesting sinkers and pellets mixed among the mollusks. When lead ammunition was finally banned, the populations began climbing back, turning the scaup into a conservation success story. The species now numbers around 420,000 birds globally, a recovery driven entirely by removing one toxic contaminant.
• Greater scaups breed across Arctic tundra in Canada and Siberia, arriving in May when the ice barely begins to crack — females lay clutches of 7 to 10 eggs in ground nests hidden among sedges and dwarf willows. The ducklings fledge in just 35 to 40 days, racing against the clock before Arctic autumn freeze, and by August the entire breeding population is already heading south. This compressed breeding season means the scaup has one of the tightest life calendars of any duck, with zero margin for late springs or early freezes.

At a glance

About the Greater Scaup

As the Greater Scaup glides effortlessly across the water, its sleek, black head and yellow eyes seem to slice through the ripples, leaving a trail of subtle disturbance in its wake. With each stroke of its broad, grey wings, the bird propels itself forward with a quiet efficiency, its webbed feet paddling in perfect synchrony beneath the surface. In the fleeting moments of dawn and dusk, when the light dances across the waves, the Greater Scaup's iridescent feathers shimmer with a soft, ethereal beauty, a testament to the understated elegance of this unassuming, yet remarkable, creature.

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