Naturespeak A naturalist's view of the world

January 8, 2008

Kestrel of Many Colors

Filed under: Uncategorized — wykes @ 9:34 pm

  An un-announced guest dropped by Jeff Read’s Gibraltar house the other day. The well dressed visitor stopped in for lunch and while delivering a poorly aimed stab at his food, was propelled into the porch window with near fatal force. Fortunately, he survived his experience -and in spite of it -will likely return to sample the fare.

  The house crasher was an American Kestrel bent on nabbing a sparrow. His intended prey veered off just shy of the window and left the pursuer little time for course correction.  The predator and the pane were introduced to each other in short order. This could have been the high impact end of a wonderful career. Many other bird eating raptors, such as the larger Cooper’s and Sharp-shinned Hawks, suffer this fate while pursuing their trade in the close vicinity of houses. This ill fated hunter struck with a glancing blow that knocked him for a loop but apparently didn’t break anything.  After a few minutes of counting stars he shook off the cobwebs and flew off.

  Mr. Read took full advantage of the opportunity to click off a few splendid images of this splendid visitor (You know what they say about opportunity knocking!) I would like to share them with you. His detailed shots capture the incredible beauty of the bird in crisp detail (here, take a look).

  The dazed bird in question is properly known as a Kestrel, but they are often referred to as Sparrow Hawks. Considering that the species is not a hawk or a sparrow specialist, this latter name can lead to some confusion. These robin-sized raptors are card carrying members of the Falcon family – a group typified by sickle shaped wings and side burns.  Kestrels are, in fact, the smallest falcon in North America so their prey selection is limited to the likes of grasshoppers, mice and an occasional sparrow (when they can catch ‘em, that is). Besides, the name Sparrowhawk is already taken by a European bird that eats sparrows and is a true hawk (see one here).

  To be completely official, we need to call this one an American Kestrel because there is another European bird also called a Kestrel.  Take a look at this photo and you can compare the much larger Kestrel on the left with an American Kestrel on the right. All of this muddling of names happened because many of our birds were originally named by homesick Europeans. If one of our North American critters kinda looked like one of the neighborhood residents from across the pond, then it was dubbed with the old name.

  One thing that probably everyone in the world agrees to is that the American Kestrel is the prettiest falcon in the world (although I’m sure the French would disagree). The male bird is the boldest of the bunch. The distinctive male features on this pictured bird are the wonderful pastel blue shoulders and crown, speckled peach breast and solid brick red tail. Females lack the blue coloration and have a heavily barred tail. 

  Both sexes have paired black sideburns (called malar stripes by those folks looking to come up with specific terms where none are needed) and prominent spots on the back of their head (called ocelli by those same folks). Take a look at this view and you can get some sense that those spots take on the appearance of a pair of eyes on a fake face – a trait accentuated by a pointed  black “beak” coming down off the top of the head. Why, you might ask, would a bird need a fake face? Kestrels are frequently attacked by larger birds of prey, and they are able to keep these potential predators off guard by tricking them into thinking that they are being watched even when the potential prey is looking away. This, of course, works only some of the time.

  If you look carefully at both photos of this little dandy, you’ll note some dried blood on the beak and on the right foot (the other foot is pulled up out of view). This is sparrow blood spilt from an earlier kill. There is likely to be a spattering of fresher blood by days end.

January 5, 2008

Sleeping Beauty

Filed under: Uncategorized — wykes @ 10:03 pm

  Perhaps the last thing you’d expect to come across on a sloppy gray January day is a sleeping god.  Gods are omnipotent, so you’d think it would be a nearly impossible task to sneak up on one –at the very least these deity types should have guard godlets or twelve-headed mythical doglike things to warn them of approaching visitors, right?  I guess not.

  Well, I just walked up to the ancient king of Athens today and peered right into his secret chamber without being smit (or is it smote, or smotted?).  I was smitten, however. Cecropia’s winter lair turned out to be a silken cocoon and like all royal homes, this one was certainly worth a second look

   The earthly personification of the ancient ruler was a Cecropia Moth – a species of moth named after the mythical figure. Why this impressive insect is named after a half man/ half snake fish is beyond me, but it is a member of a group known as the giant silk moths.  All the members of this robust family are named after Greek and Roman gods, so it’s a clan thing.  Even the family name itself, Saturnidae, is in honor of the child-eating god Saturn.  It happened to be Saturn’s day when I discovered the cocoon – coincidence? Maybe.

   The tough woven cocoon was adhered to a leafless silver maple branch. It was within easy mortal’s reach so I pulled it down for closer examination. The impressive larvae of this species make their over-wintering home in late summer/early fall and then pupate within a protective casing of their own making. (Here’s a picture of the caterpillar as it is about to sip from a caffeine free Pepsi can).  After a long winter’s rest, the adults emerge early the following summer.  Sporting a wingspan of 6 inches, these beautiful beasts are the largest moths in North America (look here and you’ll see what I mean).

  For the time being, this potential summer beauty was hidden within a silk purse. I thought you’d like to get a glimpse of the resting king, so I broke off the branch and carried it home in order to peek inside.  I made a careful incision through the papery tough outer layer to reveal an inner chamber of steel wool consistency. Both cocoon layers were woven by the caterpillar to create a weather and predator proof package. 

  A final cut into the inner sanctum exposed the pupae (look here) hidden deep within this multilayered sleeping bag. A wadded dry skin – the last shed of the caterpillar – lays crumpled off to one side.  I gingerly removed the pupae and took several shots of it before quickly returning it to its original location. Close scrutiny of this marvelous entity (see here) provides an image more akin to a pharaoh’s casket than to a Grecian urn.

  The dark leathery skin is sculpted with all the features the insect will exhibit as an adult. From the front (see here) the folded wings are evident. Two ear-like antennae curve down from the head and give the pupae a peculiar rabbitish look. A side view (see here) clearly shows the prominent segments of the abdomen and the breathing holes called spiracles that will provide the future moth with life giving air. Inside this casing, the caterpillar has already made the miraculous transformation from land based slug to aerial acrobat, but it needs to wait until the world is ready for its summer revelation.

  I carefully sutured the cocoon back together (see here) so that the creature can emerge in natural style when the time is right.  I’ll keep it in my un-heated back porch to insure that it doesn’t dry out and protect it from the legions that would delight in the destruction of Cecropius Rex. Rest easy my noble sir.

January 3, 2008

Swan Song

Filed under: Uncategorized — wykes @ 11:32 am

   I will be the first to admit that putting the title of “Swan Song” on a piece about swans is a corny thing to do, but there was no other choice.  I wanted to talk about swan songs – specifically Tundra Swan songs- so what else could I do?  It probably would have been more insightful and clever to label this as “Call of the North,” “Tundra Tunes,” or “Winter Windpipes,” but then again it really doesn’t matter what I call it. “Pygmalion” was the original title of “My Fair Lady” and that didn’t affect the stage or theatre success of the musical, did it?  O.K. then, I’m here to talk about “Cygnus columbianus – the Musical.” 

  As you might expect, Tundra Swans are visitors from the high north (the north slope of Alaska & the Yukon territories).  They come south every winter to bide their time in the relative comfort of our southern cold season. Most of the migrating population flies to the east coast and Chesapeake Bay, but a significant number do their time here in the western end of Lake Erie at the mouth of the Detroit River.

Tundra Swans are large white birds – no surprise there (take a look at this pair of mature birds). The young birds retain their youthful gray head and neck feathers and a pinkish bill (see here in my portrait). Adults weight around 16 pounds and can stretch the tape at over 4 feet long from beak to tail. Their wingspan is over 7 feet, so there is nothing small about these northern visitors. The younger birds are pretty much full size as well. As big as they are, Tundras are still slightly smaller than the non-native Mute Swans.  The adult birds are best distinguished from those obnoxious year-round residents by their solid black beak with a speck of yellow near the eye. Mutes have an orange beak with a tremendous black knob near the face (I will explain why I think these birds are obnoxious at a later time when I discuss “Mute Swan – the Tragedy”).

  The single most distinctive thing about Tundra Swans is their sonorous voice which can carry for miles on a still winter day.  Mutes, in spite of their name, can make a few nasal vocalizations but they can’t hold a candle to their native cousins. The collective effort of a few hundred singing Tundra Swans creates an aural experience for the listener. Like a Himalayan mantra or a Gregorian chant, the vacillating tone envelops you.  When issued through a frosty river fog by ghostly shapes out on the river, the overall effect is just plain mesmerizing.

 

  It is difficult to describe the call. Some have characterized it as a “cooing” or a “whoohing” or even a “soft ringing bark.” I like that last description even though I have no idea what it means. I prefer to compare the sound to that issued by those winged monkeys in the Wizard of Oz – the movie.

 

  Ask any opera singer and they’ll tell you that a good voice is all in the pipes and the lungs (actually they will tell you to go away first, but in my musical they manage to snort out an answer). Let me tell you, Tundra Swans have great pipes. Their trachea (windpipe) is over 3 feet long.  Because their neck is less than 2 feet long, the windpipe tube needs to extend down below the breastbone, loop up into it, coil around inside it, come back out, and loop back over to enter the lungs. Take a look at my drawing of a tundra swan breastbone (sternum) to see how the trachea loops around inside the keel (the lower pipe end doubles back and extends up the throat while the top pipe end continues back over the sternum to the lungs). The similarity of this arrangement to the convolutions of a trumpet or trombone is no coincidence.

 

  I’d like you to look at another view of a swan’s breastbone. Both this example, and the one I sketched, came from two birds that literally sang their swan songs last winter. Both were found dead from starvation.  Fortunately, by examining their remains we can appreciate the living birds even more. This is an end-on view of the leading edge of a swan sternum.  Note the large cavity inside the keel where the wind pipe went.  Also note that this view looks like a laughing gargoyle (weird, eh?).

 

  While our opera diva creates her glass shattering effects by manipulating her voice box (larynx), the swan does it with a similar organ called a syrinx.  Unlike our voice box, the swan’s tone adjuster is deep within its chest at the point where the windpipe divides into two short bronchial tubes at the lungs. The human larynx creates an Adam’s apple throat lump, but swans can’t afford to have such a thing, so they locate it at the far end of the tube for aerodynamic reasons.

 

  The result of all this Tundra Swan tubing is a great symphonic sound. I can recommend that you make the trip to the Detroit River shore at Lake Erie Metropark to witness this firsthand.  You’ll need to do it before March because that’s when the fat lady sings and the orchestra moves north.

January 1, 2008

Bug in a Cat-tail Rug

Filed under: Uncategorized — wykes @ 9:39 pm

  The winter edition of the cat-tail moth is a bug wrapped in a cat-tail rug.  The tiny larvae of this aptly named moth – also known as the Shy Cosmet – pass the cold season within the fluffy seed heads of cat-tails.  They are in the enviable position of never having to leave the security of their comforter on a frosty winter morn like us warm-blooded types.

  Finding one of these caterpillars is a difficult thing – but finding a bunch of them is easy.  All you need to do is locate a puffed out cat-tail head. In normal circumstances, a cat-tail seeks to attain nudity by the time spring comes along. It hopes to surrender its cottony seed blanket to the four winds and remain as a bare spike. Any creature seeking long-term shelter in this temporary refuge has to take steps to insure that its cover won’t be blown. Cat-tail Moth caterpillars, therefore, weave a silken net around the entire cat-tail head before entering the winter season.  When the seeds start to peel away they are held within the confines of the silk bag. A poofy cat-tail with a hair-net is the result. Here you will find caterpillars – lots of them.

  I took this cat-tail inside in order to perform a larvaectomy. Since the caterpillars eat the micro sized seeds where they attach to the central spike, the cottony down was free to peel away like a sheet of sheep wool. There were no insects immediately apparent – it’s not like cockroaches dashing for cover when the light is turned on. No, you need to wait a second or two before you begin to see one sticking its head out from the fluff.  Pretty soon another shows itself and before you know it you have a small confused herd on your hands. There were ten individuals in this single head.

  The caterpillars came in different sizes, depending on their stage of growth, but none exceeded 8 mm in length.  Here’s a detailed view of one of the larger larvae venturing out onto the Martian surface of my fingertip.  The dark head capsule distinguished the forward end and the pale body was pin-striped with brown.  As a caterpillar it was required to motivate itself via 16 stubby legs but it moved at a good clip. You’d expect it to be somewhat sluggish but such was not the case.  It was actually difficult to get a stop action shot of the little beast.

  I attempted to gather in the whole team of ‘pillars for a group shot, but had to settle for this shot of some of the slower ones.  I suppose their agitation was driven by the need to seek shelter.  They have absolutely no defense from predators other than their security blanket. Exposure is not an option.  Even under cover they are in constant danger. Chickadees, those little black and gray dynamos of the bird world, actively seek them out with their probing little beaks.

  Assuming that another curious naturalist or bird doesn’t come along to disrupt the natural order of things, these caterpillars should pupate and emerge by mid summer.  The adult Cosmet is nothing to brag about, but as a proud member of the micro-lepidopteron clan they hold their own with a 22 mm. wingspan of fringed cappuccino colored wings adorned with a few eye spots.

 I re-introduced my little friends to another undisturbed cat-tail head. I felt slightly guilty about destroying their home for the sake of science, but also did it as a meaningless gesture to bring in the New Year. Unfortunately, the chickadee that was watching me the whole time probably saw it as an act of feeding. From Cat-tail to Cosmo to Chickadee – the cycle of life continues into the year 2008.

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