AMPHIBIANS AND REPTILES - 0F | GRAND CANYON • NATIONAL PARK Natural History Bulletin No. 9 Grand Canyon Natural History Association July, 1938 GRAND CANYON NATURAL HISTORY ASSOCIATION ADVISORY COUNCIL Educational Development: Dr. John C. Merriam, President, Carnegie Institution. Dr. Harold S. Colton, Director Museum of Northern Arizona. Geology: Mr. Francois 3. Katthes, U. S. Geological Survey. Paleontology: Dr. Charles E. Resser, U. S. National Museum, Dr. Charles W. Gilmore, U. S. National Museum. Mammalogy: Mr. Vernon Bailey, U. S. Biological Survey. Ornithology: Mrs. Florence M. Bailey, Fellow, American Ornithologist's Union. Herpetology: Mr. L. M. Klauber, San Diego Museum of Natural History. Botany: Dr. Forrest Shreve, Desert Laboratory, Carnegie Institution. Ethnology: Dr. Clark Wissler, American Museum of Natural History. Archeology: Mr. Harold S. Gladwin, Gila Pueblo. Mr. Jesse L. Nusbaum, Superintendent, Mesa Verde National Park. AMPHIBIANS AND REPTILES OF GRAND CANYON NATIONAL PARK NATURAL HISTORY ASSOCIATION BULLETIN NO. 9 July, 1938 National Park Service, Grand Canyon Natural Grand Canyon National Park History Association This bulletin is published by the Grand Canyon Natural History Association as a pro­ ject in keeping with its policy to stimulate interest and to encourage soientific researoh and investigation in the fields of geology, botany, zoology, ethnology, aroheology and related subjects in the Grand Canyon region. This number is one of a series issued at irregular intervals throughout the year. Notification of the publication of bul­ letins by the Association will be given, upon date of release, to such persons or institu­ tions as submit their names to the Executive Secretary for this purpose. The following bulletins are available at present: No. 1 - Mammals of the Grand Canyon Region 25/ No. 2 - History and Exploration of the Grand Canyon Region...... ..15/ No. 3 - Trees of Grand Canyon National Park 50/ No. 4 - Contributions to Grand Canyon Bird Study.• Lay No. 5 - Contributions to Grand Canyon Geology IB/ No. 6 - Check-list of Plants of Grand Canyon National Park 60/ No. 7 - Prehistoric Nan in the Southwest 25/ No. 8 - Check-list of Birds of Grand Canyon Nati onal Park 25/ M. R. Tillotson, Edwin D. MoKee Superintendent Exec. Sec'y. and Editor This Bulletin - 25/ 1 AMPHIBIANS AND REPTILES OF GRAND CANYON NATIONAL PARK By Hatt N. Dodge* Introduction W HERE are those horrid snakes? I want to see them." This remark, frequently addressed to the keepers at a large metropolitan zoo, expresses the attitude of many persons toward snakes and, to a lesser degree, toward lizards, toads, salamanders and turtles. That certain creatures should seem repulsive, and at the same time exercise a strong appeal indi­ cates a peculiar contradiction in mankind's emotional makeup. Superstition, imagination and exaggeration have built up a mass of false information regarding these creatures. This has engendered an entirely groundless fear and hatred of these animals, especially snakes, and has brought about a widespread persecution resulting in considerable economic loss, particu­ larly to farmers. PARK REPTILES, IN GENERAL, ARE HARMLESS HE Grand Canyon is favored with an interesting assort­ T ment of reptilian life which, with the exception of the rattlesnake, is entirely harmless to man. Rattlesnakes are very rare within the Park and, as far as the writer can ascer­ tain, not a single fatality from snakebite has taken place in the area since it was placed under the jurisdiction of the National Park Service in 1919. * To Messrs. Klauber and Perkins of the San Diego Museum of Natural History, the writer expresses his gratitude for valuable assistance in giving detailed technical advise and constructive ori- ticism in the preparation of this paper. 2 GRAND CANYON OFFERS FERTILE FIELD FOR REPTILE STUDY ISITORS to Rational Parks are, in the main, interested V in the enjoyment of superlative scenery. But moun­ tains, lakes, glaciers and sunsets alone do not constitute scenery. Without the forests, the flower-filled fields, and the animals that inhabit them, these remaining vestiges of the onoe great American wilderness would be barren indeed. People are gradually learning that a richer, deeper enjoyment of these soenic areas may be derived through acquiring a basio knowledge of the magnificent manifestations of Kature repre­ sented there. In the Grand Canyon, climatic conditions have provided a great variety of habitats which enable the visitor to find concentrated here a wealth of plant and animal life. Reptiles are no exception to this rule and of fer a most inter­ esting field for study. The casual visitor will find that a little knowledge about the reptiles that he may meet on road or trail will af­ ford many moments of pleasure. For the herpetologist, there remains in Grand Canyon much to be learned from a detailed study of reptilian life which will contribute to the meager knowledge now on hand. It is the purpose of this publication to offer the interested visitor in non-technical form an out­ line of the information now available on amphibians and rep­ tiles of this National Park, and at the same time provide the research student with a synopsis of the work already accompli­ shed as a basis for further study. The writer wishes it to be fully understood at the outset that he has done no scientifio work whatever in this field. He has merely attempted to ool- lect all information available on Park amphibians and reptiles and to present it in systematic, accurate, readable form. PREHISTORIC AfiPHIBIAlB AND REPTILES AT GRAND CANYON RAHD CANYON affords access to a remarkably complete Q cross-section of rock layers representing the earth's early history. It holds in its walls an invaluable record of the processes by which the earth's crust was built and also of the plants and animals that inhabited this portion of our sphere during past ages. In several formations in its upper 5 walls and in certain Painted Desert horizans, (extensions of which are known to have overlaid the present surface rocks of Grand Canyon National Park) have been found footprints of land and water animals. Careful studies of these imprints indi­ cate that they were probably made by amphibians and reptiles some of which were similar to modern forms inhabiting the re­ gion today. The Grand Canyon, thus, not only aids the scien­ tist in determining the relative position occupied by amphi­ bians and reptiles in the development of life throughout the ages, but also stimulates his interest by offering for obser­ vation the evolutionary remnants of a form of animal life that at one time dominated the face of the earth. AMPHIBIANS AND REPTILES AMONG EARLIEST LAND ANIMALS OOLOGISTS have presented a mass of evidence to show Z that land animals developed from water-inhabiting forms that, through innumerable generations, were able to divorce themselves gradually from a water environment. Since such a drastic change of habitat must have taken a great amount of time, it is logical to expect that many of the animals of in­ termediate generations lived both on land and in water. Am­ phibians of today possess the ability to do this, or, perhaps we should say, are restricted by it. The adults may live in moist locations on land but for the fundamental processes of reproduction, they must return to water where the young spend the first stages of the life cycle. The individual during his life thus follows the evolutionary program of his kind or, as Dr. Cockerell* aptly remarks, "climbs his family tree". If we may accept the amphibian as the form of life link­ ing the land and water vertebrates, the reptiles may be consi­ dered as among the first types of purely land-inhabiting animals. This belief is borne out not only by geological evidence, but also by the close relationship of amphibians to reptiles as indicated by the fact that these are the only groups of land vertebrates which, in common with the fishes, are cold blooded. Obviously for a life in the water where temperature changes are comparatively slight, an ability to regulate the body temperature is not of vital importance. * See references at end. 4 PRIMITIVE CHARACTERISTICS HAVE BEEN RETAINED NDER atmospheric conditions where temperature fluctua­ tions are great, inability to meet such changes is a seriouUs menace to life. It is interesting to note, however, that many forms of amphibians and reptiles, have been able to survive regardless of this handioap. They have merely been restricted to certain environments by it. Their vital pro­ cesses are slowed down as the thermometer drops and they are correspondingly aocelerated by a rise in temperature*. Thus all reptiles and amphibians require a fairly warm habitat to enable them to capture their food and they cannot survive in regions where low temperatures prevail. Many forms, however, have the ability to hibernate, or go into a state of dormancy, when they retire to protected spots, and thus they are able to pass through periods of cold weather. For this reason some amphibians and reptiles are numerous in temperate regions where the winters are not too long and with the coming of warm weather they reappear in large numbers. Amphibians which re­ turn to activity with the arrival of warm spring rains have given rise to the superstition, still widely believed, that they "came down with the rain". Another superstition that "horned toads" may remain dormant for years sealed in stone Cavities is entirely without foundation in fact. ENVIRONMENTAL REQUIREMENTS DETERMINE DISTRIBUTION HE limitations imposed upon reptiles and amphibians by their environmental requirements naturally have much to do Twith their distribution throughout the world and, in a sim­ ilar manner, throughout the Park. Adult amphibians require moist locations and must have at least semi-permanent pools of water for breeding, hence they are not found far from mois­ ture.