Tuesday, November 23, 2010

Feeding habits of the Northern Shoveler

Northern ShovelerFemale Northern Shovelers, Fernhill Wetlands, Forest Grove, Oregon on 19 October 2010 by Greg Gillson.


Many birders are a bit hesitant when it comes to identifying female ducks. The hen's plumage is camouflaged browns. Clues from the brightly-colored wing are often concealed, folded up and covered by the scapulars and breast feathers. It doesn't help, either, that they frequently keep their bills hidden, tucked away in the scapulars as they rest.

But what's this? All those ducks swimming around seem to be feeding with their head half way under the water! Looking around, it doesn't take long to spot plenty of drakes feeding in the same manner--Northern Shovelers all.

Called "spoonbills" by hunters, for their long spatulate bills, Northern Shovelers are the 4th most abundant duck on the Pacific Flyway, following Northern Pintail, Mallard, and American Wigeon.

Shovelers are included in the "puddle ducks" or "dabblers" that primarily feed by upending--head under the water and tail and legs in the air. But not so the Northern Shovelers. They feed more on the surface, pushing their bills through the water, straining out food with the sieve-like lamellae--a comb-like structure on the edges of the bill. All ducks have lamellae, but on the Northern Shoveler it is especially well-developed.

These ducks commonly feed in small groups that circle about, stirring up mud with their feet. They take more animal matter than most puddle ducks, about 65% animals to 35% plants. Snails and water boatmen seem to be favorites, according to John K. Terres in his 1980 reference work, The Audubon Society Encyclopedia of North American Birds.

However, whereas Terres indicated that the feeding groups are "three or four" in size, I have often noted groups of a hundred or more in a tightly packed raft, circling and circling as they feed. As they feed, the males (only?) constantly grunt a mechanical chug-kuk chug-kuk chug-kuk....


Northern ShovelerA whole raft of nearly headless ducks! Feeding Northern Shovelers, Fernhill Wetlands, Forest Grove, Oregon on 19 February 2006 by Greg Gillson.