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Reptiles and Amphibians of Yosemite National Park (1946) by Myrl V. Walker


REPTILES

The few reptiles that live in the world today are but a small remnant of a once mighty race or division of our vertebrate animals. Those people who today are frightened at the sight of a little garter snake or spiny lizard would have been shocked beyond description had they met face to face some of the giant dinosaurs or other reptiles of the ancient past. Even if such a meeting had occurred, there is little doubt but that most of the reptilian giants would have been little interested in their human observers. Many of the ancient reptiles were for the most part herbivorous and subsisted on plant life. Only in recent times (geologically speaking) and in a last effort to maintain their race, have the majority of reptiles become carnivorous or flesh-eaters, rather than herbivorous.

If we could but piece together each and every adaptation made by the reptiles of the past in their effort to secure food, find shelter, and reproduce their kind, we would unravel in detail a most marvelous story. This story would tell us why snakes have lost their legs, why some lizards are legless, blind, and burrowing, why some lizards are covered with spines, and why some snakes have developed a poison apparatus for use in securing their food.

Taken all in all, the reptiles have not been outstandingly successful in their efforts to maintain themselves, and those few forms that we still have with us today are all the more interesting because of their varied and often seemingly useless variations, habits or adaptations. We often wonder why some reptiles are so brilliantly colored, why some reptiles “play dead,” and why some reptiles spread their heads. And again why do some reptiles vibrate their tails, and why have other reptiles developed a rattle on the end of that vibrating tail.

Generally speaking, reptiles may be identified by the fact that their body covering is composed of rather dry scales, easily recognized in most common snakes and lizards, but somewhat modified in the turtles and tortoises. They differ from the mammals and birds, above them in the scale of life, by having “cold blood” and thereby. being restricted in their habitats by the temperature of their surroundings. They rank above the amphibians and fishes since they are far less dependent on water. They have no larval stage, and the development of their bony skeleton, especially their skull and jaws, often set with firmly attached teeth, is a specialization which distinguishes them from the amphibians.

It is unfortunate that there is not a more genuine interest in the study, observation and recognition of reptiles—snakes, lizards, and turtles. Many of these forms are not difficult to capture, and are easily kept in captivity; however, they should be kept in captivity only if the observer is conscientious in his efforts to secure worthwhile information on their behaviour and food habits. Our reptiles in general are just as worthy of adequate protection as are the mammals and birds, and the harmless forms should be considered an integral part of the biotic picture of any community. The few poisonous forms that do exist should be studied carefully so that they may be readily identified and their real danger recognized. Only when their presence may actually constitute a danger to human life should we tolerate the selective destruction of these forms that otherwise are of economic value and a part of the balance of nature.

Although representatives of each of the three different divisions of reptiles—turtles, lizards, and snakes—are present in the Yosemite National Park, their numbers are somewhat limited. Only one turtle has been recorded from this region. The lizards are more numerous with nine species present, and at least thirteen different snakes have thus far been collected within the boundaries of the Park.



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