Visit any of the ponds in our area right now and chances are you will see a scattering of ducks; there's also a pretty high chance that among them will be Northern Shovelers. While most ducks can be easily divided into those that dive for their food and those that 'up-end', the shovelers have another trick up their sleeve to ensure that they make best use of the feeding opportunities offered to them and it's all down to that eponymous, shovel-like beak. If you watch Northern Shovelers feeding, the chances are that you won't see them dive or up-end (though they do do the latter at times); instead, you will see them feeding at the surface and this is where that peculiar beak comes in. Shovelers filter feed in a very similar manner to a number of other aquatic or semi-aquatic animals, such as flamingoes - and even some whales! They achieve this by having a series of comb-like bristles - called lamellae - along the cutting edge of the upper mandible, together with a series of narrow grooves along the edges of the lower mandible. By using their tongue as a kind of pump, they are able to take water into the beak, then push it out through these bristles and grooves, the end result being that the water passes through and any morsels of food get trapped in the bill. An ingenious mechanism that clearly works well as it has evolved so many times in a bunch of unrelated organisms. Check out the Northern Shovelers next time you visit a pond and check out how they are feeding.
Northern Shovelers can look pretty crazy when filter-feeding. Often, a pair will go round and round in circles, working nose to tail; this probably works best as each bird benefits from the upwelling of water caused by the feet of the other bird. Here, three birds are all working with each other [photo by Mike Crewe]
Having just recently taken the upper photo myself, it was coincidence that Sam Galick sent me this picture at the same time and inspired this post - for Sam had noticed that he had caught a fine shot of the shoveler's special equipment...
Zooming in on the photo above, here you can see the comb-like lamellae along the cutting edge of the upper mandible [photo by Sam Galick]
