This article first appeared in the April 2004 issue of the San Antonio
Many wild ducks possess a grace of form that has made them a favorite subject of artists. Intricately carved wooden replicas of such picturesque species as the Pintail (Anas acuta) add to the interior decor of many houses. I don’t recall seeing any such replicas of the Northern Shoveler (A. clypeata), the relatively stocky build and oversized, flattened bill of this species perhaps skewing it toward the comedic end of the spectrum.
A typical duck bill is at once a combination of both specialized and utilitarian features. The generally flattened shape facilitates the collection of soft aquatic plants, while the comb-like lamellae around the margins filter out food from water and mud. The prominent tooth-like nail at the tip can be used to uproot water plants as well serving as a weapon during disputes. The exact proportions of this basic bill design vary between species, tailored to the feeding habits of their owners.
As the bill would indicate, the Northern Shoveler is a filter-feeding specialist. Water is drawn into the bill and then expelled through the lamellae by the tongue in a rapidly repeated sequence. Another less visible but equally telling adaptation to a specialized diet is the relatively long intestine. Shovelers consume relatively more invertebrate prey than do related ducks, this animal diet lending the flesh a strong taste generally disliked by hunters.
Wintering Shovelers seek out eutrophic waters such as the shallow muddy polders at Mitchell Lake where they may congregate in the thousands. Typically, Shovelers feed while swimming, the large bill immersed just below the surface. Often, feeding Shovelers will form a line, the bill of each duck in the water, immediately behind the bird in front. Alternatively, feeding flocks may form dense rafts of ducks circling in a pinwheel formation.
Northern Shovelers occur across the Northern Hemisphere, breeding in the Temperate and Arctic Zones and wintering south to the Tropics. Three related species occur in the Southern Hemisphere: the Cape Shoveler (A. smithii) of South Africa, the Red Shoveler (A. platalea) of South America, and the Australian Shoveler (A. rynchotis) of that country and New Zealand.
On this continent, most Shovelers breed in wetlands on the northern plains, from Kansas and Colorado north to the Canadian prairie provinces, with smaller numbers of birds breeding north to central Alaska and scattered pairs across the eastern states. Like most ducks, they are of necessity opportunistic when selecting breeding sites, the bulk of the population relocating north and westward in response to drought on the prairies. Pintails under such circumstances have been observed to relocate as far away as Siberia. Shovelers have not been proven to disperse as far as that, although such seems certainly possible.
Pairing typically occurs on the wintering grounds, the male following the female north. The nest is concealed on the ground in dense vegetation close to water. The female alone incubates the six to fourteen eggs and tends the precocial young. It has been observed that Shovelers must often spend more time feeding than do most other ducks, such that incubating females are obliged to spend additional time away from the nest.
Hatching occurs in about three weeks and the young are able to fly at around six weeks of age. Initially the young look “normal,” the remarkable bill shape not becoming apparent until the second week. In common with other ducks, heavy losses of eggs and young frequently occur. In contrast, the adults may occasionally be surprisingly long-lived, one banded Northern Shoveler surviving twenty-one years in the wild.
Males retain their dull summertime eclipse plumage longer than do most ducks, which accounts for the many drab individuals that arrive in Texas in late summer and fall, full breeding plumage often not being attained until late December.
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