Naturespeak A naturalist's view of the world

March 13, 2008

Who’s That Knock’n?

Filed under: Uncategorized — wykes @ 7:28 pm

I know why there are little pieces of bark on the snow.  The maples in my yard are beginning to swell up with March sap, but the barkage on the ground beneath them isn’t due to this seasonal buffing up. It’s a woodpecker thing. I know this because I watched the antics of two woodpecker species in my yard and noted that the only evidence of their passing was this layer of bark flakes on the snow cover.  The unintentional educators in this case were a Downy and a Red-bellied Woodpecker.

  Up in the branches of even the healthiest of trees there are always dead branches and hidden rot spots which are host to burrowing insects (take a look through these branches, for instance). Woodpeckers are exquisitely made to exploit these nutrition hot spots. They peel away bark with abandon in order to expose tunnels in the dead wood underneath. That they are messy feeders is a natural part of their profession.

  I noticed the Red-bellied bird first, because it is the larger of the two and the one that happened to be right in front of me.  It’s loud “churr churr” call also called attention to itself. These are striking birds (pun mildly intended) with dramatically black & white barred backs and a dashing (pun) stroke of bright red on the back of their heads. The males have a red hood all the way to the base of the beak while the females only have red up to the top of the head.  My bird was a male.

  The second bird was a male Downy Woodpecker – the smallest of its kind in North America.  These diminutive little woodies are also decked out in contrasting black & white stripes, but allow the pattern to possess their entire body (except their chests). This male bird had a red spot on the back of its head. The girl birds lack this extra piece of body ornament.

  Both of these wood birds were actively feeding in the upper branches and performing their search and seizure mode of feeding.  The Red-bellied concentrated on the larger limbs while the little guy focused on the smaller upper branches.  Bark was filtering down through the twigs, although I can’t say for sure which pieces were the result of Red-bellied labor or Downy diligence.  Regardless, they were both unsuccessful and moved on after only a few minutes.

  All of this, of course, leads me to a few thoughts on woodpecker biology and etymology (how they go about their calling and what we call them).  The chisel-like woodpecker bill is a natural for removing wood as is their re-enforced spongy skull for tolerating the mind crushing blows, but we give little thought to their incredible tongues. Most species, including my two yard birds, have extremely long non-muscular tongues which enable them to probe into insect tunnels (our tongues are muscular hunks of flesh rooted at the back of our throats).  The tongue structure is so long that it actually curls around the back of the skull and originates at the nostrils. An extremely thin Y-shaped bone called the hyoid accounts for most of this length, with the actual tongue making up only the tip. 

  Oddly enough, there is a difference in the feeding behavior between the males and females of these species.  The Downy females tend to feed lower down on the tree than her male counterparts. The male Red-bellied actually has a longer bill and a wider tongue than the female. No one is quite sure why this is, but the result keeps the sexes separated and insures equal use of the available food. There might be some life lesson hidden here for our human use of the refrigerator, but I’ve yet to discern what that might be.

  While the Downy is aptly named – it is a fluffy little thing – the Red-bellied is a supreme example of a poorly named animal.  We can blame this man (the one pictured here) for that. This is Carl Von Linne the incredibly gifted 18th century scientist who devised our current method of scientifically naming things.  He’s done good life work, but dropped the ball on this one. The Red-bellied Woodpecker really doesn’t have a red belly at all.  Sure, if you look at it just right and have good light you’ll see that it does have a rosy tint to its belly, but really. Is that the most distinctive thing on this bird?

  The only thing I can think of is that Carl’s wife ate all the available food in the refrigerator on that fateful naming day in 1758, so he was out of his mind with hunger. If only the Linne family had worked out the woodpecker system of food resource use, things might have been different. Since I don’t even know if there was a Mrs. Linne, I certainly could be barking up the wrong tree on this one.

  Should you do some research, however, and find that there was a “Mrs.” and that her portrait depicts her as a portly woman, then I rest my case.

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