Thursday, October 23, 2008

Ducks got baleen.

Northern Shoveler, Anas clypeata.

I came across a freshly deceased Northern Shoveler the other day. It was lying next to a slough, a few feet onto the shore, exactly as shown above. There was no sign of trauma, at least from this aspect (I didn't turn it over, or touch it in any way).

The pose provided a close look at that amazing shoveler bill, relative to body size the largest bill in any of our ducks. The comb-like lamellae that fringe the upper bill resemble the baleen of a whale, and are to some degree functionally analogous. Both are filter-feeding structures, one for small sea life (crustaceans, cephalopods and fish), the other for smaller aquatic life (zooplankton, phytoplankton and other plant elements including seeds).

Shovelers draw in water from the surface of the water, often very muddy water, at the front of the bill. The tongue squooshes it laterally out through the lamellae. Small edibles are trapped, to be drawn backward and swallowed. Shovelers spend a lot of time skimming the surface, filtering large volumes of water. This feeding method reduces the need for the undignified up-ended foraging behaviour common to other dabblers.
Northern Shovelers in happier times.

1 comment:

cedrorum said...

Very interesting. I'm embarrassed to admit that I didn't realize, or forgot from my ornithology classes, that shovelers have lamellae on their upper bill.