Little Blue Bill — the Lesser Scaup
by Darcy Thomas
Little Blue Bill emerged from the water with a crayfish in his bill and swam to the edge of the lake near a grassy bank. In a sudden frenzy of splashing water, a Red Fox pounced upon his neck and pulled him from the water. Little Blue Bill became immediately immobile with head extended, eyes open, and wings held close to his side as though feigning death. The fox, being young and inexperienced, was confused by the stillness of his prey and set the duck down. In this moment of inattention Little Blue Bill seized the moment and got away. This is one of the Lesser Scaups interesting behaviors that help it adapt to its’ environment and survive.
Lesser Scaup (Aythya affinis), known affectionately as Little Blue Bill, is the most abundant and widespread of the North American diving ducks. Lesser Scaup are medium-sized being larger than a Green-winged Teal but smaller than a Canvasback. They tend to use inland lakes more than Greater Scaup. Being social birds, they form large flocks, called rafts, on rivers, lakes, and wetlands throughout the fall and winter. You usually see them flocked with other ducks such as Canvasbacks, Redheads, Ring-necked Duck and Greater Scaup. They eat aquatic invertebrates such as mollusks and crustaceans as well as plants and seeds.
Lesser Scaup look like they forgot to comb their hair, having a pointed rear crown. Their black heads have gloss that can vary from purple to green depending on the angle. These black and white diving ducks (females are chocolatey-brown with a white patch next to the bill) with blue bill and yellow eye present a difficult ID due to their similarity to the Greater Scaup. Luckily, these two are often seen together which allows the birder to compare the two and note their differences. Field ID tips such as taking time to watch them, observing several birds in the same flock, looking at the birds while they are at rest, and viewing them from various angles can help you learn to confidently identify the Lesser Scaup. It can also be helpful to have a spotting scope, so grab a friend who has one to go birding with you if you do not own one.
Most Lesser Scaup will migrate to winter grounds in the Gulf of Mexico or Central America by December, returning to Montana and other northern locales for the breeding season beginning in March. Choosing a new mate every year, they build nests on the ground hidden in tall vegetation. Eggs are laid before the nest is even finished and the final touches are added soon after. Lesser Scaup have one brood yearly with 6-14 eggs.
The population of Lesser Scaup has been declining for reasons that are not entirely clear. At Bowdoin National Wildlife Refuge near Malta, 25,000 Lesser Scaup were counted in November 1949. Since then, there has been a cumulative decline of 59%. At Freezout Lake near Fairfield, the major cause of unsuccessful nests is skunk predation. Other causes for decline may include habitat loss and contaminated diet. It is interesting to note, however, that Lesser Scaup are doing very well at Montana’s Red Rock Lakes National Wildlife Refuge where they have one of the highest densities of breeding populations than anywhere else in North America. Researchers are studying Lesser Scaup at the refuge to understand why they are faring well there when the numbers have been dropping elsewhere. What they learn may help provide information that will guide conservation efforts to protect these amazing birds from decline.