At a glance, both male and female lesser scaup (Aythya affinis) resemble miniature greater scaup. However, these dividing ducks do display some unique characteristics of their own.
The male sports a shiny black head with a purple gloss, visible in good lighting. His back is barred for a grayish appearance, but note that his sides are also very finely barred with a paler gray.
The female is yet another brown duck, but she displays a white patch near the base of her bill. She also shows some mottling on her sides.
Note that both the male and the female have a blue bill and a tuft on the back of their head that gives them a peaked or capped appearance. In flight, they display a white wing stripe on the secondary flight feathers only. The lesser scaup is among the fastest-flying of all ducks.
Best Field Marks
- Purple head gloss of male.
- White wing stripe on secondaries only.
In this species, the female tends to be the more vociferous of the pair, making “scaup” calls and peculiar rattling “kwuh-h-h-h” noises. Males may whistle during courtship.
Distribution & Occurrence
The lesser scaup is probably the most abundant diving duck species in North America. It is also one of the most likely to be seen inland. In Kansas, this duck can be found across the entire state at nearly any sizable body of water. It is common during migration season, occurs regularly in winter in smaller numbers (provided that the water remains open), and may even turn up from time to time in midsummer.
Breeding lesser scaup were recorded in Cowley County around 1928. However, there have been no further reports of breeding activity since that time.
This is a particularly active species. It can be seen flying in tight flocks with fast, sporadic movements, it spends a great deal of time diving (which it does with considerable athleticism), and it can hide quickly and efficiently when it feels the need.
The lesser scaup is highly social and collects in large groups called rafts, particularly in migration season. While it seems to prefer to associate with members of its own species, it will mingle with other diving ducks to some degree, particularly redheads.
The diet of the lesser scaup is divided fairly evenly between aquatic plants and invertebrates. Many scaup tend to eat slightly more plant matter, while younger birds and even some adults will consume animal food almost exclusively.
Backyard birdwatchers will probably not have much success attracting lesser scaup to their yards.
Hunters rely on decoys to attract lesser scaup, placing their spreads in long lines.
Telling greater and lesser scaup apart is probably the ultimate waterfowl identification challenge. The best field mark is the wing stripe, which extends only through the secondary flight feathers on lesser scaup but all the way to the primaries on greater scaup. Also, note that greater scaup are larger and chunkier, with thicker bills and rounder heads. The male greater scaup has a green gloss to his head and stark white sides, compared to the purple gloss and light gray sides of his lesser counterpart. In most cases, inland rafts of scaup will be lesser scaup, but you should always check so that you don’t miss out on a greater scaup sighting.
These species look similar in many respects. However, note that both male and female ring-necked ducks have a white ring on their bills. Also, the male ring-necked duck has a solid black back, plus a white crescent mark separating his breast from his sides. The female ring-necked duck is a little less obvious, but typically shows a white line extending backward from the eye. Watch out for hybrids of these two species—hybrids will look somewhat intermediate in appearance, making them hard to identify.
Photos, audio, and more information from Cornell’s All About Birds site.