Is that a Bill or a Beak?
By Noreen O’Brien, Purchasing, Marine Parts Express
I remember asking an ornithologist once, “Is there a difference between a bill and a beak?” His reply, “Only in a restaurant.” (Seems there is a prerequisite to being an ornithologist: one must be goofy, or worse, “punny.”)
While birds’ bills come in many shapes and sizes serving a wide range of purposes, the key factor in design is based on the need for an instrument to obtain food in an efficient manner.
Bills, made up of an upper and lower mandible (jaws) housing the tongue, are light bony structures covered with a horny sheath of keratin, the material of which our fingernails are made. No birds have teeth, though some, for instance, ducks, swans and geese, have ridges running along the interior edge of the bill acting as sieves straining out vegetable matter from water.
Bills are the equivalent of our lips, and much more. Birds’ bills take the place of our fingers and hands and are used as tools in feeding, nest building, combat and a means of communication, among other things.
Some birds, like puffins, grow a seasonal sheath, larger than the bill and of bright colors, which they shed once the breeding season is past. Pelicans are similar in that they grow a knob-like protrusion on the top mandible, thought to act as a display ornament during the breeding season. Still other birds, like the hornbills of Africa, have a very large bill with a bony casque, a permanent part of the structure of the bill, the function of which is unknown.
Each bill design helps to fill the species’ niche in the natural world. Shorebirds have bill lengths according to the depth they must dig in the sandy beaches of where their favorite food thrives. Several species may frequent one area of shoreline, but each species is aiming for a different meal in a different layer of the sandy substrate.
Plovers, which run short distances between stabs at aquatic meals close to the surface, have shorter, stubbier bills than do dowitchers, which stand in a small area, systematically stabbing in the mud like a sewing machine with their longer, thinner, slightly decurved bills.
The tip of the oystercatcher’s bill is flattened from side to side to enable it to pry open oysters and mussels. Willets, long-legged sandpipers, need longer bills to reach just the right depth in the sand under the shallow water they like to wade in as they probe for aquatic insects and worms. The long-billed curlew, nearly double the size of the willet and with longer legs, has an almost ridiculous looking, 9-inch long decurved bill it uses to probe marine worm burrows.
Some bills have a hook at the tip. Eagles or hawks, for example, catch their prey with their feet and talons and need to have powerful bills with hooks to tear apart the flesh of their catch. Some water birds, like ducks, have “nails” on the tip of their bill to crop the vegetation they forage as it sways in lakes and ponds.
Herons, deep waders standing on long legs, spear their food with a long dagger-like bill poking out from the head sitting atop a long neck, all designed for the additional length needed for thrust as they reach for prey before swallowing their catch whole.
Songbirds give away their food preferences by the shape and size of their bills, too. Flycatchers have relatively broad bills with bristles at the base acting as a net of sorts, aiding the catching of insects on the fly. Warblers have tiny, pointy bills, used as pincers to collect an insect sitting on a leaf.
Seedeaters have bills adapted to facilitate husking and crushing seeds from a variety of plants. For example, a crossbill manipulates a pinecone with its tongue to line up with grooves between the mandibles, crack the cone open and then use the fine crossed points at the tip of the bill to extract the seeds.
Hummingbirds are a marvelous example of an odd bill structure. These birds, sometimes with a bill nearly as long as their bodies (sword-billed hummingbird of South America), use their needle-like bills to probe into flowers to sip nectar with their long tongues. To return the favor to the flower, the hummer carries pollen on its face feathers to the next flower, pollinating it. Hummers also use their long bills as forceps to catch insects.
This piece could go on to the length of a book, there is so much that might be said about birds’ bills. For now, however, the next time you notice a bird eating, observe it carefully. See if you can determine what it is eating, how it came to collect the item and how it is manipulating the food to get what it needs from it.
Please do write to me with your observations.
Till next …
Rest assured, when calling Marine Parts Express (toll free at 877.621.2628) for your engine parts, you will indeed receive a bill, not a beak.
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Marine Parts Express is a division of Water Resources, Inc., a privately held Maine Corporation.
For all your marine engine parts needs, call us toll free at 877.621.2628, or outside the U.S. at 207.882.6165.
April 7, 2011 / Noreen O'Brien / 1
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