Naturespeak A naturalist's view of the world

March 27, 2008

Yes, the Can Can

Filed under: Uncategorized — wykes @ 8:55 pm

 Even though I just addressed the subject of Canvasback Ducks only two weeks ago (March 8), I believe this is a waterfowl well worth revisiting. My reason for going back to back with Bullnecks is that I have a bird in hand this time (and you know what they say about a bird in the hand).  My specimen is a dead bird, unfortunately – one those unfortunate ducks that succumbed to a late winter/early spring bout of starvation that hit our wintering population. Hundreds of the birds were found dead from Lake St. Clair down to Lake Erie. All those that were recovered and analyzed proved to be suffering from malnourishment. Oddly enough this appears to be a natural phenomena and the overall effect on the whole population should prove to be minimal.

  I recovered this handsome specimen from the slushy frozen waters of Lake Erie a few days ago. It is a drake Canvasback that remained buoyed at the surface by its dense water-repellant covering of contour feathers.  The oily surface and dense downy layer combined to resist the effects of water and mass. This buoyancy served the bird well in life and delivered it neatly to the shore upon its death. It would be less than respectful not to spend a few minutes looking at this elegant fowl.

  The black breast and rump are cleanly kept apart by a much lighter mid section. From a distance Cans appear to be a simple combination of a cinnamon head on a stark black and white body (like these live birds). Close up, the white feathers exhibit complex gray linear patterns called vermiculations (literally “worm lines”).  Take a close look here and you can see the details of this intricate feathering décor.  Male ducks tend to exhibit much more of this line work than their feminine counterparts.

  One of the more interesting fallacies addressing the name of the Canvasback stems from a seemingly logical explanation that completely ignores the appearance of these back feathers. Back in the bad old days, when ducks were hunted for market, the birds were often shipped to the restaurants in canvas bags. According to those who should know better, each bag was stenciled with the words “send canvas back” to insure that the sacks were returned for re-use. Most of these bags were stuffed with Canvasbacks because they were the most desired species and so they naturally became known as, well, you guessed it.  The problem is, this is plain wrong. This popular game bird had long been known by hunters as the bird with a back that looked like bleached canvas.  It’s not that hard, son!

  Canvasbacks are diving ducks extraordinaire. Their large bluish feet are located well back on the body and are fully webbed (see here). Even the tiny hind toe is flattened to enhance the bird’s swimming ability. This flat toe, called a hallux, is a key characteristic of all members of the diving duck family such as the Scaups, Red heads, and Ring-neck Ducks.  When swimming underwater, the feet are held out to the side and employed with simultaneous strokes. Longer-than-average toes create a huge webbed paddle area for propulsion.

  No other diving duck has a beak quite like that of the Canvasback. In profile it is a ski slope running even with the slant of the forehead (see here). My friend John Audubon penned a suitable tribute to this beak in his “Birds of America.”  A snippet from his lengthy discussion states that “the dorsal line (is) at first straight and declinate, then slightly concave, direct for a short space near the tip where it is incurved, the ridge broad and concave at the base, narrow at the middle, enlarged and convex at the end.”  In other words, it is like a ski slope. It’s not that hard, John.  

  Lining the inside edges, just out of view, this marvelous beak is equipped with a series of comb like ridges called lamellae.  Take a gander…er, I mean a drake…at this view with the mouth partially open and you’ll see this feature exposed on the lower mandible. Fortunately John took the time to count these ridges and found there to be 50 on the upper mandible and 105 “inferior” and 105 “superior” ridges on the lower mandible. For his patience I am eternally grateful.  This gives me time to mention that the Canvasback also has a thick fleshy tongue that is 2 ½ inches long and furnished “with a series of bristly filaments.” 

  The tongue, in this case, is as important as the beak. Lamellae act like sieve plates that trap food as the tongue enlarges and squeezes out each mouthful of water. A primary plant eater like the Canvasback can rip up sections of water celery, push out the watery mouthful and retain only the vegetable goodness for swallowing. Yes, the Can can.

  I hope you’ll agree that time spent in the presence of this red-eyed beauty is time well spent. Perhaps I’ll leave you wanting to know more about this critter?  If so, please send me a cloth bag stuffed full of hundred dollar bills and be sure to mark it “Send Canvas Back.”

No Comments »

No comments yet.

RSS feed for comments on this post. TrackBack URL

Leave a comment

Powered by WordPress