Greater Scaup vs Lesser Scaup: What Are The Differences?

Small Fish Scale (Atia) and Greater Scaup (A. marila) are two closely related North American diving duck species in the genus Aythya. At least one of these medium-sized waterfowl species can be seen anywhere between Alaska in the north and Florida in the south.

It can be difficult to tell where these two birds appear together, so how do birders tell the difference?

You can tell the difference between a large and a small skull by comparing the shape of the head. Larger fishes have a rounded crest, while the feathers on the head of smaller fishes form a slight hump or crest toward the rear. When seen in flight, the greater lepidopteran has a white stripe on its wings that extends from the secondary flight feathers to the primary flight feathers. In Lesser Scaup, this stripe fades into the primary color.

large scale

small fish scales

In addition to these differences, males have whiter flanks than males, and females have more white plumage on their faces than their close relatives. Making accurate identifications poses a huge challenge for birders, especially when you see birds at greater distances.

Large and small scaled are gregarious birds that can congregate by the hundreds or thousands in suitable habitats. These two species do not usually form mixed groups where they occur together.

You can spot both diving ducks in some of the same large inland waters, but for the most part, Greater Scaups are winter visitors to U.S. coastlines, while Lesser Scaups are more commonly found in inland wetlands and lakes.

Read on to learn more about the difference between large and small skulls.

Closing a bigger Scaup

Which is bigger, Greater Scaup or Lesser Scaup?

The large and small heads are very similar in size. Predictably, The Greater Scaup is the larger of the two. Read on to learn how these two North American ducks compare.

Larger Scaup Size

• The large head measures 15.3 to 22.1 inches (39 – 56 cm) in length.
• They have a mass of 25.6 to 48.0 oz (726 – 1360 g).
• Their wingspan measures 28.4-31.1 inches (72-79 cm) from wingtip to wingtip.

Smaller Scaup size

• Lesser Scaups are 15.3 to 18.1 inches (39-46 cm) long.
• They weigh 16.0 – 38.4 oz (454-1089 g).
• Lesser Scaups have a wingspan between 26.8 and 30.7 inches (68-78 cm).

As you know, size is not the best field marker to distinguish these two species because there is too much overlap. Read on to find out which of these two ducks you’re more likely to spot.

Close-up of small fish scales

Which is more common, Greater Scaups or Lesser Scaups?

Lesser Scaup is more common than Greater Scaup and is much more widely distributed in the United States than its slightly larger relatives. Small scalps can be seen in any of the lower 48 states of the United States, as far north as Canada and Alaska, and as far south as northern South America.

Greater Scaups are northern birds bred from Alaska and northern Canada. In winter, these migratory waterbirds head south to the waters of the Atlantic and Pacific Oceans. They also overwinter on some large inland bodies of water, such as the Great Lakes.

Close-up of a female Greater Scaup

Other Differences Between Large and Small Fish Scales

The most obvious difference between big and small scalps is in their head shape and feathers. Listening to their calls and noting their habitat are also important clues for identification. Read on to learn which differences to look for.

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Head shape is probably the best field marker to distinguish these two very similar waterfowl. Lesser Scaups have a small tuft or bump on the top of their head. In contrast, macrocephalics have larger and rounder heads.

This bump on the Lesser Scaup’s head is visible toward the back of the head, and the overall head shape is somewhat egg-like. Be aware, however, that these birds tend to flatten their crowns before diving or during other activities.

female small scale

bill shape

The difference in beak shape between the two species is relatively minor, but every little bit counts when trying to tell these two thorny species apart! Lesser Scaups have a slightly shorter beak with a concave top edge. The bullhead’s beak widens toward the tip, making it appear wider when viewed from the front.

Habitat

Sometimes it’s easy to get a good idea of ​​a bird’s identity without looking closely at it. That’s because these birds tend to prefer different habitats.

Chinfish prefer marine environments during the non-breeding season, although they are also frequent visitors to the Great Lakes. Lesser Scaups prefer to live on shallow bodies of freshwater, although they also use estuaries and other saltwater environments.

A group of Greater Scaup

call

Females of both species purr or bark more than males. Male chrysalis call when on display, whereas male chrysalis are usually silent. However, when you do hear it, the call is a short bleat from the male chrysalis and a more drawn-out buzz from the male chrysalis.

life

Stripe studies have shown that the two diving ducks have similar lifespans in the wild. Larger fish have been recorded to be over 22 years old, and the oldest known small fish lived to be over 18 years old.

A small group of Lesser Scaup

feather difference

Smaller and larger Scaups have nearly identical plumage. The iridescent head luster of male Lesser Scaups tends to be more purple, while male Greater Scaups appear greener.

Head color may help, but either species can display either color depending on the quality and angle of the light. Differences in wing color are a more reliable indicator.

Read on to learn more about these wing feather differences.

flank

The color of the flanks (sides) of a swimming or standing Scaups is another useful tool for reliable identification. The flanks of male ichthyosaurs are almost pure white, while the flanks of male ichthyosaurs have fine worm markings, creating a dirty gray appearance.

Female and male Greater Scaups in flight

Spread your wings and fly

Both species have a white stripe on the upper side of the wing when viewed in flight. In the Lesser Scaup, this white streak is prominent on the secondary, but does not reach the primary and turns brown instead. The white wing stripes are better developed on the large shoulder blades, extending closer to the body and into the primary feathers.

small scales in flight

Female Greater Scaup and Female Lesser Scaup

Females of both species are mostly chocolate brown, with black beaks and yellow eyes. Both species also have white feathers at the base of the beak, although it is not always present on all female small skulls. The above-mentioned differences in head and beak profile are the most valuable field markers to distinguish small and large heads in females.

Junior Greater Scaup and Junior Lesser Scaup

It is especially difficult to distinguish macrocephaly from microcephaly in juveniles. Birders should look for the same differences in head profile, habitat and distribution that apply to adults. Both species tend to congregate in groups of their own, so keep an eye out for adult males nearby to help strengthen your identification.