Northern Shoveler’s Adaptation For Feeding Cool

By Michael Burke
A LARGE mixed flock of ducks and geese are busily feeding in a shallow pool. My eyes are drawn to a half dozen birds in the foreground. The iridescent green heads suggest Mallards, but the huge, broad bills irrefutably say, “Shovelers.” Those bills look slightly ridiculous—a classic duck bill, but expanded to comic-book proportions.

After an extraordinarily warm and sunny late fall day, the morning dawned cool and gray with a strong promise of rain. The annual Waterfowl Festival was concluding that day in Easton, MD, but we opted to pass up the exquisite artists’ renderings for a chance to see some of the Chesapeake Bay’s renowned water birds in the flesh.

I was heading off for serious orthopedic surgery, and this weekend was the last chance to get in some birding before I’m housebound during recovery.

The Northern Shoveler (Anas clypeata) has the biggest duck bill for its size of any North American species. The large, spatulate bill slopes nearly straight down from the top of the duck’s head, giving the impression that the bird has no forehead. Shovelers are slightly smaller than Mallards, but that over-size bill somehow makes them seem larger.

That silly beak serves a useful purpose, of course. Shovelers are dabblers, just like Mallards, Pintails and Teals. Mallards frequently tip up—that undignified feeding posture with head underwater and rear end skyward—as they feed on vegetation or bottom-dwelling organisms. Shovelers, on the other hand, are content to skim the surface of the water or shallow mud. That’s where the oversize bill, with its comb-like feature along the sides, earns its living.

The Shoveler’s tongue is similarly adapted. It has matching fringing along each side. Working in concert, the bill and tongue are quite effective in straining tiny organisms out of the water. The Shoveler uses the extremely large surface area of its big bill to filter huge quantities of pond water while efficiently capturing the nutritious organisms and seeds it finds there.

Shovelers are among the first winter ducks to arrive on the Chesapeake. It is early November and they are already well-established at Blackwater National Wildlife Refuge along with hundreds of Mallards and Northern Pintails, not to mention thousands of Canada and Snow Geese.

The Shovelers come from North America’s most important duck nesting grounds, the “prairie pothole” area, a vast region centered in the northern Great Plains. These ducks breed in an area that includes all of the Canadian provinces west of Ontario and in the United States down to Nebraska and across to California. Usually, the only time they are seen east of the Mississippi is during migration or the winter. From November to spring, they inhabit an uninterrupted, narrow band down the California coast then straight across from Baja to Florida, and finally up the seaboard to the mid-Atlantic region.

Their nests are typically built in areas beyond the wetland edges. Males defend their territory and females, but only until incubation begins. Then the males retire to nearby ponds to molt. If nests are lost, the birds may re-breed, but not necessarily with the same mate.

Although some field guides suggest that the males don’t come into their full winter plumage until December, the Blackwater birds are already fully decked out. Shovelers, like many ducks, exhibit strong sexual dichromaticism—the term for when males and females show distinctly different color patterns. The males have that green head, a prominent yellow eye, and broad black bill.

With their stomachs hidden underwater, the birds we saw at Blackwater pond appear to have white breasts, chestnut sides and then another white splash before the tail. When they take off, though, we can see that their entire bodies are white except for those rufous sides. On top, they show a mixture of black and white while resting. In flight, pale blue shoulder patches are visible on each wing.

Females, as usual, are less dramatically colored. The black beak shows some yellow on the lower half. Their heads and bodies are a streaked brown. They share the pale blue shoulder patches with the males, although in females it tends more to gray than blue. Like the males, the underside of the wings is mostly white.

As I watch these birds busily eating their breakfast, though, I think that bill must be somewhat unwieldy when they’re not feeding. I even find myself wondering if that disproportionate size is a handicap during long migratory flights.

As I shift my weight off my aching hip, I wonder if there’s a flip side to my physical limitations, too. Maybe they will lead to a greater appreciation of nature’s elegance. Perhaps they helped to persuade my able-bodied housemates to rise before dawn to seek the solace of the refuge.

For now, though, it is time to put aside these thoughts and simply watch a Shoveler put his ponderous bill to good use. He has no need for such human concerns. And for a time, neither do I.–Bay Journal