Lesser Scaup

Quick Take

• Female lesser scaups do something with their eggs that looks like a mistake, though it is completely intentional. See the egg-laying behavior →
• Lesser scaups look like ordinary black-and-white ducks, but that impression only lasts until you get close enough to see what's actually there. Explore their appearance →
• Their population has been declining for years, and scientists still can't agree on why. See the population decline →
• Lesser scaup hatchlings hit a developmental milestone in their first 24 hours that takes most animals far longer. See hatchling development →

The lesser scaup is a medium-sized diving duck. They are often seen forming groups with other species of diving ducks, such as canvasbacks and the greater scaup. Lesser scaups spend much of their time on the water, sleeping, eating, and socializing there. Unlike dabbling duck species, they can dive up to several feet underwater to secure their prey.

Lesser Scaup Amazing Facts

• Of all the duck species to migrate, the lesser scaup is often one of the last to make the move, either north or south. 
• They can be found in almost all types of waters, including coastal bays and estuaries. 
• Their habitats range from as far north as Alaska down into South America. 
• These ducks typically migrate at night. 

Where to Find Lesser Scaups

Lesser scaups can be found throughout the western hemisphere. During their breeding season, they can be found in the far northern region of North America, including in Alaska. Outside of the breeding season, they live in the southernmost region of the United States, Mexico, Central America, and the Caribbean. They can be seen throughout the rest of the United States during their migratory period, and there are a few year-round populations in the United States and Venezuela. 

During the breeding season, they prefer fresh and brackish wetlands. However, they favor any water source during the rest of the year. This includes freshwater sources such as lakes and ponds, as well as coastal waters. 

Nests

Lesser scaups will make their nests on the ground. They prefer to nest along tall vegetation in prairies and wetlands. Sometimes, females will choose to build their nests on floating platforms. No matter where they build it, they always conceal the nest well among vegetation. 

In order to build their nests, female lesser scaups will make a small depression in the ground. This will serve as the foundation for the nests. Then, they will begin to add grass and other plants, as well as down feathers.

Sometimes, you may see a half-completed nest with eggs. This is because female lesser scaups will lay their eggs before finishing the nest, and then they will finish the nest around their brood. 

Classification and Scientific Name

The lesser scaup belongs to the class Aves. They belong to the order Anseriformes and family Anatidae. Their genus name is Aythya. This genus includes twelve different species of ducks. The lesser scaup’s scientific name is Aythya affinis.

Their genus name is derived from the ancient Greek word aithuia. This is an unidentified seabird that appeared in many of the popular writings of the time period. Their species name comes from the Latin affinis, or related to, because of their similarities to the greater scaup.

Lesser Scaup Size, Appearance & Behavior

Adults grow 15 to 19 inches long on average. They can weigh 1.0 to 2.5 pounds, with males typically being heavier than females. Their wingspan is 27 to 31 inches. 

Adult males appear black and white at a distance, but closer inspection reveals a dark glossy purple head, black breast, and finely barred gray back. They have white markings along their wings. You can identify females by their brown coloration and the thick, wide band at the base of their bills. 

This species is also known as the little bluebill or just broadbill. This is because they have a distinctive blue bill. 

They are not extremely vocal, especially compared to other species of dabbling ducks. However, males do have distinct mating calls, with females having similar responses. As a result, mating time is typically the loudest season for these ducks, especially as their young come into the world with their own calls. Their name may derive from the female greater scaup’s call, which sounds like “scaup, scaup.” 

Migration Pattern and Timing

Lesser scaups are some of the last ducks to migrate each season, both to and from the breeding grounds. They are nighttime migrators who tend to only travel a medium distance each year. 

Most populations will spend the winter months around the Gulf of Mexico. However, some individuals prefer to migrate further south. 

Diet

Like many other species of diving ducks, they are omnivorous. The majority of their diet consists of aquatic invertebrates. However, they will also eat aquatic seeds and plants. Although they dive for their food, they usually forage in waters less than sixteen feet deep. 

What does the lesser scaup eat?

This duck will eat mussels, clams, leeches, insects, and snails. The main plants in the vegetative portion of their diet are aquatic sedges and grasses. 

Predators and Threats

Lesser scaups and their nests are vulnerable to many different threats, including predation. In recent years, they have faced a population decline. However, while there are many theories as to the cause of this decline, there have been no studies able to confirm these. Some of the probable causes include climate change, hunting, limited resources during migration, and changes in geography. 

There are also many predators of adult, juvenile, and unhatched individuals. These may vary based on the area that the individual settles, but many are present nonetheless. 

What eats the lesser scaup?

One of the most notable predators of the lesser scaup is the red fox. This species will prey on adults, young, and eggs in the nest. They will also hunt adults outside of breeding season whenever they come ashore. Predators on land include snakes, raccoons, and mink. They may also fall prey to other birds, such as red-tailed hawks and owls.

Reproduction, Babies, and Lifespan

Lesser scaups are monogamous within a season, although they may find a different mate the following year. Once they arrive at the breeding grounds and build their nest, they will typically have only one brood. These broods contain anywhere from six to 14 eggs.

Each egg is around 2.2 inches long and 1.5 inches wide. The shell is pale olive to slightly green in color. 

The incubation period lasts from 21 to 27 days. Once hatched, the young are covered in down and have their eyes open. They are ready to leave the nest within 24 hours.

Lesser Scaup Population

There are around 3.7 million lesser scaup individuals in the world. Although their population has declined, there are measures put into place to help protect this species. This includes the Conservation Reserve Program (CRP), which is working to protect nesting habitats.