April 2015

Vol. 43, No. 2

Front Cover: April 2015

Northern Shoveler by Barry Van Dusen

Once again, Bird Observer offers a painting by the artist who has created many of our covers, Barry Van Dusen. Barry, who lives in Princeton, Massachusetts, is well known in the birding world. Barry has illustrated several nature books and pocket guides, and his articles and paintings have been featured in Birding, Bird Watcher’s Digest, and Yankee Magazine as well as Bird Observer. Barry’s interest in nature subjects began in 1982 with an association with the Massachusetts Audubon Society. He has been influenced by the work of European wildlife artists and has adopted their methodology of direct field sketching. Barry teaches workshops at various locations in Massachusetts. For more information, visit Barry’s website.

Northern Shoveler

The Northern Shoveler (Anas clypeata) is a beautiful dabbling duck with a large, spatulate bill adapted for filter feeding on small aquatic invertebrates. The former genus name Spatula and the current species name, from the Latin clypeum meaning shield, both refer to the bill shape of this elegant duck. The medium-sized shoveler is sexually dimorphic in plumage. In breeding plumage—December through May—the male has a shining green head and neck, and chestnut flanks and belly that contrast sharply with its white breast. The female is mottled light brown but can be distinguished from other female ducks of similar plumage by her spatulate bill. In flight, both sexes have white underwings. Males have a large blue patch on their forewings; females have a similar patch of gray. Juveniles resemble females. In nonbreeding plumage, males have gray heads and the rufous underparts are muted. Northern Shovelers are monotypic, with no subspecies recognized. They are, however, closely related to the three shoveler species of the Southern Hemisphere.

Shovelers breed from northern Alaska south through the prairie pothole regions of western Canada and the United States. In the east, breeding is patchy through the Great Lakes, the Saint Lawrence Seaway, and southern Hudson Bay area. Shovelers also breed in Europe and Asia. This species has bred sporadically in Massachusetts, especially on Monomoy and Plum islands where it is a fairly common migrant. Shovelers are rare or uncommon in other parts of the state, although they have become progressively more common since the 1920s. Most Northern Shovelers are migratory, wintering from Washington State across much of the lower half of the United States to Mexico, and Central America. On the East Coast they winter north to southern Massachusetts. Of the dabbling ducks, Shovelers are one of the latest spring migrants and earliest fall migrants.

Shovelers are usually monogamous but are occasionally polygynous. Pair formation occurs on the wintering grounds, usually by the end of February. Courtship by the male includes took-took calls, a display in which the male swims away from the female, showing off his shimmering green head. Other displays involve the tip-up posture, wing flapping, and short jump-flights. The male Shoveler defends the core of his home range during breeding season more than any other of the dabbling ducks. Territorial males will chase conspecifics while swimming or flying and may fight with lunging, wing flapping, and biting. Threat displays include open bill and bill-jabbing, and head pumping with an upward-pointing bill. Shovelers may also be aggressive on the wintering grounds.

Northern Shovelers produce a single brood per season. Breeding habitat includes shallow wetlands, ponds, and parklands—habitat typical of the prairie pothole region. The female selects the nest site, usually in vegetation no more than a foot high and within 150 feet of water. She also makes a simple nest scrape, which she lines with down. The clutch is 10–12 pale olive or greenish gray eggs, incubated by the female alone for 22-25 days until the synchronous hatching. The female may give a flapping distraction display if the nest is threatened and if flushed, may defecate on the eggs as she departs, which may deter predators. The chicks are precocial, covered with down, eyes open, capable of locomotion, and within a day feed themselves on aquatic invertebrates and plants. The female leads the young to water shortly after hatching. She remains with the brood for about seven weeks until fledging. Males eventually desert their mate and young and form cohesive bachelor flocks. During their flightless period during molt, they become solitary and secretive, hide in vegetation, and feed less. After molt, they once again form flocks.

Shovelers forage by swimming with their bills in the water, the comb-like lamellae along the broad, spatulate bill straining invertebrates from the water. Their diet consists primarily of swimming invertebrates, especially Daphnia and other cladocerans, and also includes seeds. They usually forage in open water but may also dabble in the mud of the bottom, using a tip-up posture. They also glean food from submerged vegetation. Because Shovelers tend to stir up their environment when foraging, they are sometimes used as beaters by other species such as phalaropes.

During breeding, adult females, eggs and young are preyed upon by foxes and other mammalian predators. Skunks and ground squirrels regularly destroy their nests. Typical avian predators include crows, magpies, and gulls. Hunters kill several hundred thousand Shovelers every year, and habitat loss due to the conversion of wetlands to agricultural lands is widespread. But Breeding Waterfowl Survey data suggest increasing or stable population numbers, possibly influenced by recently improved breeding habitat. Despite hunting pressure, habitat loss, and predation, the future looks promising for this lovely duck species.

William E. Davis, Jr.

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