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Lesser Scaup Life History


Lakes and Ponds

Lesser Scaup breed in the prairie pothole region in the United States and Canada north throughout the boreal forest and tundra zone. During the breeding season, they use fresh and brackish wetlands with emergent vegetation as well as prairies and hayfields. Outside of the breeding season, look for them in all types of water bodies including ponds, lakes, reservoirs, coastal estuaries, and coastal bays.

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Aquatic invertebrates

Lesser Scaup eat primarily aquatic invertebrates such as mollusks, insects, and crustaceans, but they also eat aquatic plants and seeds. They often forage in water that is less than 16 feet deep, using their feet to propel them underwater. To capture aquatic invertebrates in soft muddy substrates, scaup stick their bill into the mud and quickly open and close it while swimming forward.

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Nest Placement


Lesser Scaup nest on the ground in tall vegetation in prairies, hayfields, fresh and brackish marshes, and lakes with sedges, bulrushes, and cattails. Sometimes females build nests on floating mats of vegetation. The nest is always well concealed by vegetation.

Nest Description

Females make a small depression on the ground and slowly add grasses, other plant material, and downy feathers to make a saucer-shaped nest. Unlike other birds, females start laying eggs before the nest is complete, and continues to build the nest while she is laying eggs.

Nesting Facts

Clutch Size:6-14 eggs
Number of Broods:1 brood
Egg Length:2.2 in (5.7 cm)
Egg Width:1.5 in (3.9 cm)
Incubation Period:21-27 days
Egg Description:Pale to dark olive or greenish buff.
Condition at Hatching:

Covered in down with eyes open. Ready to leave the nest in 24 hours.

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Surface Dive

Lesser Scaup are members of the diving duck group, which catch food underwater unlike the dabbling ducks (such as Mallards). Like other ducks, scaup sleep on the water and often tuck their bill under their back feathers. They are social and frequently flock with other diving ducks including Canvasbacks, Redheads, and Greater Scaup during the nonbreeding season. During courtship, males flick their wings and tail, toss their head backwards, and push their head feathers down to create a sleek look. Females, in response to a pursuing male, stretch the neck, lift the chin, and swing the bill side to side while calling. Lesser Scaup are generally monogamous only during the breeding season; they choose new mates every year. Females are more likely than males to return to the same breeding sites the following year. Compared to other waterfowl, Lesser Scaup are stragglers when it comes to migration. They are often one of the last ducks to move south after breeding, sometimes staying on the breeding ground until things start freezing up. They're also one of the last species to head back north from the wintering grounds.

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Low Concern

Lesser Scaup are common throughout their range, but numbers slightly declined between 1966 and 2019, according to the North American Breeding Bird Survey. Partners in Flight estimates the global breeding population at 3.7 million and rates them 11 out of 20 on the Continental Concern Score, indicating a species of relatively low conservation concern. Several factors may be contributing to the Lesser Scaup's decline, including hunting, climate change, limited resources on migration routes, hydropower dams, contaminants, logging, and oil and gas extraction, but compelling evidence supporting these hypotheses is lacking. In an effort to increase Lesser Scaup numbers, the North American Waterfowl Management Plan coordinated actions to improve resources along their migratory route. The Conservation Reserve Program is also working to protect nesting habitat in the Prairie Pothole Region of central North America by partnering with farmers to remove environmentally sensitive land from agriculture. The U.S. Fish and Wildlife Service carefully manage duck hunting and limit the number of individuals hunters can take every year based on population size. Hunters took on average about 205,000 Lesser Scaup per year in 2019 and 2020.

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Anteau, Michael J., Jean-Michel DeVink, David N. Koons, Jane E. Austin, Christine M. Custer and Alan D. Afton. (2014). Lesser Scaup (Aythya affinis), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Lutmerding, J. A. and A. S. Love. Longevity records of North American birds. Version 2020. Patuxent Wildlife Research Center, Bird Banding Laboratory 2020.

Partners in Flight. (2020). Avian Conservation Assessment Database, version 2020.

Raftovich, R. V., K. K. Fleming, S. C. Chandler, and C. M. Cain (2021). Migratory bird hunting activity and harvest during the 2019–20 and 2020-21 hunting seasons. U.S. Fish and Wildlife Service, Laurel, MD, USA.

Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski Jr., K. L. Pardieck, J. E. Fallon, and W. A. Link (2019). The North American Breeding Bird Survey, Results and Analysis 1966–2019. Version 2.07.2019. USGS Patuxent Wildlife Research Center, Laurel, MD, USA.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.

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