Friday, February 1, 2019

Lesser Scaup

A Lesser Scaup drake, or male Bluebill. In addition to the bill color, notice the peaked head.

     Lesser Scaup (Athya affinis) are the most common of our freshwater diving or bay ducks, referred to as pochards in other parts of the globe. Though often just called divers, pochards around the world (there are 16 species in 2 different Genera worldwide) share some similar traits. First of all, most do not inhabit oceans and swim using only their feet (which like other diving birds are placed well back on their bodies). Sea ducks use their wings as well as their feet when swimming. Most male freshwater diving ducks also have similar plumage patterns, of dark patches with light colors (but no colorful patches on their wings), bright colored eyes, and very similar voices due to having the same voice box apparatus (called fenestrated bullae). They all share a common ancestor.
     All Scaup are often called "Bluebills" by hunters and others due to the color of their beaks, which are also tipped in black. Lesser Scaup (sometimes referred to as Little Bluebills) are medium sized ducks, males averaging 1.8lbs, females 1.6lbs. They were first described by an English naturalist named Thomas Campbell Eytan in 1838. The Genus name Athya is Greek for "sea bird". The other members of the Genus, all winter visitors here in the DC region are: Canvasback, Redhead, Ring-necked Duck, and the very similar Greater Scaup. Greater Scaup are larger, have wider beaks (sometimes they're called Broadbills), longer white wing stripes, and rounded heads. Lesser Scaup are smaller, with thinner bills, shorter white wing stripes, and a peaked appearance to their heads. While some claim that Greater Scaup have a greenish look to their heads as compared to the purplish gloss of the Lesser, this is for all practical purposes useless in the field. As a general rule Lesser Scaup do prefer smaller bodies of water and freshwater, while the much less numerous Greater Scaup prefer open and often brackish or saltwater. There is tremendous overlap however and mixed flocks of both can be found, especially the closer you get to the coast. Occasionally both scaup may hybridize or do so with ring-necked ducks as well.
     The word "scaup" some say is a corruption of the Scottish term "scalp" referring to clams, oysters, and mussels that are favored prey items. Others think it's due to a corruption of Dutch or French wording for scallops. Others think it's due to the sound made by the hen.
     Although they feed quite a bit on mollusks as mentioned, either diving or just tipping up to grab them, scaup also feed on plants, seeds and other invertebrates. They seem to really like amphipods such as scuds. Unlike most diving ducks, they may feed at night.
     Since scaup feed on a fair amount of plant material, they do not have the extreme fishy taste of some other diving ducks and are thus considered mild tasting table fare. They are considered much less wary than other divers, and are said to decoy and be lured in fairly well. As they are also the most numerous of all diving ducks, they are often hunted.
     But their numbers are historically down, dropping 59% since 1966. The reasons are not well understood as to why, as they nest in the upper Northwest and in many areas in fairly undisturbed land. Conservation efforts and stricter game laws have not seemed to make any difference. Many think that the declines may be due to climate change, though their numbers are still considered to be secure. Estimates are that there some 3.8 million Lesser Scaup, though their similarity to Greater Scaup (who do nest somewhat more Northwards) makes accurate counts difficult.
     Scaup nest in the pothole areas of the upper Northwest of Canada and Alaska. They are among the last birds to start migration, often waiting until the waters are frozen, forcing them to begin their journeys to wintering grounds. Their migration is often a very drawn out affair. Interestingly, their migration patterns have changed historically, with now many wintering over in the Great Lakes area, many think to take advantage of eating the now numerous numbers of the invasive introduced Zebra Mussels. As these mollusks filter out quite a bit of pollutants and contaminates, some think this may be unhealthy for the ducks. They are also among the last waterfowl to return in the spring, some still migrating in mid May. They are considered the most southerly of our migrating diving ducks, some reaching South America, the Caribbean, and occasionally straying into the Pacific and Europe.
     But when they arrive at their wintering grounds, they do so in a splendid manner. Rafts (flocks of ducks on the water) of hundreds and even thousands of birds are not rare. While they prefer the company of their own kind, they will sometimes have mixed flocks, particularly with other freshwater divers like Greater Scaup or Ring-necked Ducks.

A drake (male) Lesser Scaup mixed in with a small group of Ring-neck drakes.
     Scaup form new pair bonds yearly while overwintering. They are among the last ducks to pair up. Males make up 70% or so of the population, so finding a hen to pair up with is not always easy. Scaup are usually at least two years old before mating. Interestingly, the males also do not stay with the hen for very long after she starts nesting.     Hens choose dry areas within 200' of water to nest in, which is different from other diving ducks who often nest precariously near water. Scaup actually lay their eggs while still building their nests, 8-14 olive buff eggs. Older hens lay more eggs and have a better success rate than younger birds. Hens have been known to dump their eggs into the nests of other scaup.The eggs hatch between 21-28 days later. As soon as the fluffy down on the young dries, they can dive underwater to escape danger. Adults have been known to play dead when grabbed by predators, though this has not been noted in ducklings. Often hens form creches, where 1-3 hens tend to the young of multiple nests. Young are abandoned early, often before the 49 or so days it takes them to learn how to fly. With a lot of luck, they can live up to 18 years.


  1. Thanks for accessible write-up. The picture placing the Ring-necked and Less Scaup together was most helpful. I liked the term 'blue bill' but for the longest time thought it was Ruddy ducks!