The White-Tailed Deer of the Organ Pipe Cactus National Monument, Arizona
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The white-tailed deer of the Organ Pipe Cactus National Monument, Arizona Item Type text; Thesis-Reproduction (electronic) Authors Henry, Robert Stephen Publisher The University of Arizona. Rights Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. Download date 27/09/2021 06:35:33 Link to Item http://hdl.handle.net/10150/555138 THE WHITE-TAILED DEER OF THE ORGAN PIPE CACTUS NATIONAL MONUMENT, ARIZONA . by Robert Stephen Henry A Thesis Submitted to the Faculty of the I SCHOOL OF RENEWABLE NATURAL RESOURCES In Partial Fulfillment of the Requirements For the Degree of MASTER OF SCIENCE WITH A MAJOR IN WILDLIFE ECOLOGY In the Graduate College THE UNIVERSITY OF ARIZONA 1 9 7 9 STATEMENT BY AUTHOR This thesis has been submitted in partial fulfillment of re quirements for an advanced degree at The University of Arizona and is deposited in the University Library to be made available to borrowers under rules of the Library. Brief quotations from this thesis are allowable without special permission, provided that accurate acknowledgment of source is made. Requests for permission for extended quotation from or reproduction of this manuscript in whole or in part may be granted by the head of the major department or the Dean of the Graduate College when in his judg ment the proposed use of the material is in the interests of scholar ship. In all other instances, however, permission must be obtained from the author. SIGNED: APPROVAL BY THESIS DIRECTOR This thesis has been approved on the date shown below: 9 - & K 1YLE K. SOWLS Date Professor of Wildlife Ecology ACKNOWLEDGMENTS Funding for this project was provided by the National Park Service under contract number CX-8000-6-0040e Additional support and facilities were provided by the Arizona Cooperative Wildlife Research Unit, at The University of Arizona. I wish to thank superintendent Ray Martinez and the staff at Organ Pipe Cactus National Monument for their cooperation and assis tance throughout this study. The support of Terry Peters, the Resource Management Specialist, was invaluable. I also thank Kevin Coates for his help in the field and lab, Dr. Lyle Sowls for his constant advice and support, and Drs. Paul Krausman and Phil Ogden for reviewing the manuscript. iii TABLE OF CONTENTS Page LIST OF T A B L E S ................................................ vi LIST OF ILLUSTRATIONS....................................... vii ABSTRACT . ............................. viii INTRODUCTION.............. 1 STUDY A R E A .................................................... 3 METHODS AND M A T E R I A L S ........................................ 9 Distribution and Abundance .......... .......... 9 Habitat .................................................. 9 D i e t ............ 10 Water Use ........... ............ ...... 12 Competition ........................................... 12 P r e d a t i o n ............................................... 13 R E S U L T S ................................... 14 Distribution and Abundance ................ 14 H a b i t a t .................... 21 Vegetation ....................... .......... 21 Topography............................................ 2? Diet . ............... 35 Water Use . ................. 40 Waterholes ......................... 40 Behavior at Watering Sites ........................... 43 Interspecific Competition ..................... ..... 45 Predation ........................ 54 Human Interference ......................... ....... 57 Park Visitors .... ................. ....... 57 H u n t i n g .......................... 6l DISCUSSION.................................................... 63 Factors Affecting Present Distribution in Ajos ...... 63 Vegetation............................................ 63 Topography.................... 64 W a t e r ............................................... 65 iv V TABLE OF CONTENTS— Continued Page Factors Affecting Abundance ..... ................. 65 Extinction Probability ......................... ....• 68 SUMMARY AND RECOMMENDATIONS ................................. 72 LIST OF REFERENCES ..................................... 75 LIST OF TABLES Table Page 1. Rainfall, in inches, at four elevations in Organ Pipe Cactus National Monument, from 1976 to 1978 ........ .. 7 2. Results of three time-lapse camera surveys of waterholes in the A jo Mountains .................................... 20 3. Percentage cover and composition of vegetation in the Bull Pasture study site, Ajo Mountains, Arizona .... 28 4. Percentage cover and composition of vegetation in the North Alamo Canyon study site, Ajo Mountains, Arizona • 30 5» Percentage cover and composition of vegetation in the South Alamo Canyon study site, Ajo Mountains, Arizona . 32 6. Percentage occurrence of plant species in the diet of white-tailed deer in the Ajo Mountains, Arizona, 1976 to 1978 . .......................................... 36 7. Occurrence of plant species in the habitat and in the diet of white-tailed deer in the Ajo Mountains, Arizona, 39 8. Percent composition of major food items in the diets of white-tailed deer and bighorn sheep in the Ajo Moun tains, 1976 to 1978 ................................... 51 9. Frequency of prey items in the diet of bobcats and mountain lions in the Ajo Mountains, 1976 to 1978 . 36 10. Number of visitors to the Bull Pasture by month in 1977* 60 vi LIST OF ILLUSTRATIONS Figure Page 1. Location of Organ Pipe Cactus National Monument ..... 4 2. Distribution of the white-tailed deer in southwestern A r i z o n a .................................................. 15 3. Locations of sightings of white-tailed deer in the Ajo Mountains, June 1976 to July 1978 ................. 18 4. Vegetation types of the Ajo Mountains, Organ Pipe Cactus National Monument .................... 22 5. The jojoba-mixed scrub association, Bull Pasture, Ajo Mountains............ ...... ............................. 24 6. The juniper-rosewood relict woodland association, South Alamo Canyon, Ajo Mountains .......... ......... 26 7. Spring #2 Tinaja in the Bull Phsture, Ajo Mountains . 4l 8. Locations of waterholes in the Ajo Mountains .......... 42 9. Time of day of watering of white-tailed deer and bighorn sheep in June and July, 1977 and 1978 ................... 46 10. Locations of sightings of white-tailed deer, mule deer, and bighorn sheep, and approximate range of cattle in the vicinity of the Ajo Mountains, 1976 to 1978 ............. 47 11. Elevations-of sightings of white-tailed deer and bighorn sheep in the Ajo Mountains, 1976 to 1978 30 12. Diet preferences of white-tailed deer (shaded bars) and bighorn sheep ............................................ 32 13. Visitor use of Mount Ajo and the lower Bull Pasture trail, both in the Ajo Mountains ............ 59 vii ABSTRACT A smallt isolated population of white-tailed deer (Odoeoileus virginianus couesi) in the Ajo Mountains of Organ Pipe Cactus National Monument was studied from June 1976 to July 19?8 to evaluate the fac tors influencing their distribution, abundance, and probability of sur vival. The population, estimated at 6 to 12 individuals, is separated from the nearest neighboring population by 20 miles of lowland desert. The deer were most commonly observed below 4000 ft elevation, where the vegetation is described as Sonoran desertscrub. Key factors determining suitability of habitat were forage, topography, and water availability. Preferred forage species were abundant throughout the Ajo Range and were not considered to be limit ing the deer's distribution. Areas of relatively gentle slope were preferred to steeper, rockier terrain. Permanent water may be the most important factor affecting white-tailed deer distribution in this desert region. Measures of competitive overlap with desert bighorn sheep (Ovis canadensis mexicana), indicated that severe competition was probably not occurring. White-tailed and mule deer (0. hemionus crooki) occu pied exclusive territories, and thus avoided competition. Range of domestic cattle overlapped that of white-tailed deer only in limited areas. Predation, intraspecific aggression, and human interference viii were suggested as possible factors contributing to deer mortality. Threat of extinction is great due to the extremely wmqll size of the population. INTRODUCTION The Coues white-tailed deer (Odocoileus virginianus couesi Coues and Yarrow) is a common species in most of the higher desert mountain ranges of southeastern Arizona. They are generally found at elevations where there is oak(Quercus)-woodland, pinyon(Firms)-juniper (Juniperus), or other coniferous forest. They are seldom found in desert habitat (White 1957)• National Park Service records (OPCNM wildlife observation cards) indicated that there was a small population of white-tailed deer in the Ajo Mountains, Organ Pipe Cactus National Monument (OPCNM), Arizona. This rugged, isolated range rises from less than 2000 ft (610 m) above sea level to a height of 4808 ft (1465 m) on Mount Ajo. The majority of the mountain mass is less than 4000 ft (1220 m ) , and is characterized by desert-shrub vegetation (Brown, Lowe and Pase 1977)i high temperatures, and limited water. Published information on white-tailed deer which inhabit many of the desert mountain ranges in southwestern Arizona is limited. Emory (1857) recorded