By Donald Edward McHenry, Junior Naturalist.
ON occasion, visitors absorbed in viewing the almost unbelievable, unreal spectacle of the Grand Canyon will have their attention diverted for a moment from this sublime scene to a micro-drama being enacted at their very feet.
One such drama took place at Yavapai Point just outside the Observation Station at noon on April 27. The arena was the crevice of a rock. Upon the occasion about a dozen people forgot such an important thing as lunch. One can eat lunch any day, but it is not every day that the average person is privileged to watch a Striped Swift (Sceloporus c. consobrinus) gulping down an Arizona free Uta (Uta ornata symmetrica). So great was the strain upon the sympathies of one of the female members of the group of observers that she tried her best to discourage further descent of the Uta into the interior of the Swift. But the Swift was so intent upon the engulfing that it paid not the least attention to the nervous advances and kept right on gulping and gulping.
Gulp is the exact word, too. Furthermore, gulping was the only practical procedure, for the jaws of the lizard are better adapted to use in obtaining its regular diet of insects than to swallowing other lizards. Yet in spite of the usual habit of this lizard of snapping for its prey, it was now forced to employ a method of swallowing which had a certain similarity to that used by snakes. This comparison is especially worthy of note when one remembers that the lower jaw of the snake, divided in half lengthwise, is loosely hinged so that it can work on the two sides quite independently. Such movement permits the snake to reach out first one side and then the other, and by means of its recurved teeth to literally pull the victim into it, or shall we say, to pull itsself about its intended meal.
Now the lizard could not do this, for in its lower jaw the halves are fastened rigidly together so that the sides are not hinged or able to work separately. Hence our Swift was forced through necessity to swallow the Uta by a series of forward jerks, each vigorous jump enabling him to gain an advanced grip on his victim. This was sometimes accompanied by vigorous shaking of the head to aid in getting the proper hold, and although this method was very clumsy and apparently quite exhausting, the Swift did a rather complete job of swallowing the other lizard. The Uta went down head first and bottom side up.
The legs of the Uta evidently presented a more or less difficult problem. After mere than usual head shaking, however, the Swift was able to work these into a position straight to the rear, which facilitated the passage of the unfortunate lizard. All of this seemed to be real work for the Swift, for apparently so great was his exhaustion after each gulp that he had to rest four or five minutes before he undertook the next one. It took him practically the entire noon hour to swallow the Uta to a point at which only the tip of the tail extended from his mouth.
At this point the writer decided to collect the specimens as they were. The Swift was rather easily captured because of the encumbrance of the other lizard in his interior. All went well until the specimens were placed in the formaldehyde. This relaxed the jaws of the Swift and then the Uta inside him quietly slipped out to float about by itself, thus spoiling a good exhibit, much to the regret of the collector. At least we now know that lizard ate lizard as shown in the accompanying illustration, and also that for the moment this diminutive episode was even more interesting than all the witchery and enchantment of the Grand Canyon.
|<<< Previous||> Cover <||Next >>>|