Utah State University DigitalCommons@USU All Graduate Theses and Dissertations Graduate Studies 5-1955 A Study of the Winter Foraging Habits of Mule Deer in Enclosures in Northern Utah With a Test of the Half-And-Half Sampling Technique Donald R. Flook Utah State University Follow this and additional works at: https://digitalcommons.usu.edu/etd Part of the Animal Sciences Commons Recommended Citation Flook, Donald R., "A Study of the Winter Foraging Habits of Mule Deer in Enclosures in Northern Utah With a Test of the Half-And-Half Sampling Technique" (1955). All Graduate Theses and Dissertations. 3721. https://digitalcommons.usu.edu/etd/3721 This Thesis is brought to you for free and open access by the Graduate Studies at DigitalCommons@USU. It has been accepted for inclusion in All Graduate Theses and Dissertations by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. A STUDY OF THE WINTER FORA~IN~ HABITS OF MULE DEER IN ENCLOSURES IN NOR'l'HEHN UTAH \iiTH A TEST OF THE HALF- AND-HALF SAMPLIN~ TECHNI~ by Donald R. Flook ' A thesis submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE in Range Mana&emen t UTAH STATE AGRICULTURAL COLLEGE logan, Utah 1955 ACKNOWLEDGMENT I wish to express sincrer appreciation to Professor A. u. Smith, Professor G. A. ~arris, and Mr. H. s. Raskell for their guidance dur­ ing this study; to Dr. l. A. Stoddart for his advice in preparation of the manuscript; and to Professor Bliss Crandall and Dr. c. w. Cook for their suggestions in analyzing the data. Donald R. Flook l TABLE OF COirrENTS Page Introduction • • • • • • 1 Review of 11 terature • • J Location and description of study areas • • • • 11 Procedure • • • • • 19 Experiment of 1950 • • • • • • • 19 Experiment of 1951 • • • • • • 21 Experiment of 1952 • • • • • 22 Test of half-and-half technique • • • 25 Results and discussion • • • • • • • • 28 Sample size • • • • • • • 28 Test of the half-and-half technique • • • 35 Sampling results ' )8 • • • • • Comparison of sampling methods used "• • • 44 Utilization-class estimates • • • • 45 Feeding minutes observations • • • 49 Snow conditions • • .. 49 carrying capacity of study areas • • 52 Swmnary • • • • • • • 56 Literature cited • • • • • • • • • 58 Appendices • . • • • • • • • 61 LIST OF TABLES Table Page 1. Summary of previous findings concerning the winter diet of mule deer in Utah • • • • • • • • 10 2. Vegetn tion types, aerial dens! ty, and species compos­ ition of enclosed stady area, Card Canyon, Utah • • 1) ). Vegetation types, aerial density, and species compos­ ition of enclosed study area, Green Canyon, Utah • • 14 4. Vege~tion types, aerial density, and species compos­ ition of enclosed study area. foothill east of Mill- ville, Utah • • • • • • 15 5. Method of calculating forage production, consumption, and utilization of a browse species on one transect by the Wbefore-and-after" aampling technique, example-- Prunus virginiana • • • • • • • • 20 6. Method of calculating forage utilization, production, and consumption of a browse species by the "half-and­ half" sampling technique, example--Artemisia tridentate subsp. trpica • • • • 2) 7. Method of calculating estimated and actual values of forage utilization, production, and consumption, in simulated browsing experiments for evaluatl%18 "half-and- half" technique, example--Cercoearuus ledifolius 27 8. Coefficients of variation, sizes of samples ~en, and sizes of samples required for desired precision, Card Canyon enclosure, 1950 • • • • • • 29 Coefficients of variation, sizes of samples taken, and sizes of samples required for desired precision, Card Canyon enclosure, 1951 • • • • • • • • • )0 10. Coefficients of variation, sizes of samples taken, and sizes of samples required for desired precision, Green Canyon enclosure, 1951 • • • • • • • )1 11. Coefficients of variation, sizes of samples taken, and sizes of samples required for desired precision, Mill- ville enclosure. 1952 • • • • • • • )2 LIST OF TABLES (cont.) Table Page 12. Comparison of estimated and actual values of forage utili~tion, production, and consumption, simulated browsing experiment for testing ~lf-and-half• technique • • • • • • • • • • • 36 Percent utilized, weight available, weight consumed, and percent of total consumption of browse species, from sampling data, Card Canyon, 1950 • • • • 39 14. Percent utilized, weight available, weight consumed, and percent of total consumption of browse species, from sampling data, Card Canyon, 1951 • • • • • • 40 15. Percent utilization, forage available, forage consumed, and percent of total consumption of browse species, from sampling data, Green Canyon enclosure, 1951 • • 41 16. Percent utilization, forage available, forage consumed, and percent of total consumption of browse species, from sampling data, Millville enclosure, 1952 • • • • 42 1?. Estimated weight of browse consumed per deer ~ from sampling data • • • • 4J 18. Periodic average utilization-class estimates, Card Canyon enclosure, period January 6 to January 2?, 1951 • 46 19. Periodic average utilization-class estimates, Green Canyon enclosure, period February 10 to March J, 1951 • 47 20. Periodic average utilization-class estimates, Hillville enclosure, period February J to March 9, 1952 • • • 48 INTRODUCTION Mule deer provide recreational bunting to a large number of sportB­ men in Utah, and also have a high aesthetic value. Prior to settlement, deer are believed to have wintered in the valleys and lower foothill areas. However, in northern Utah agri­ cultural development bas removed many valleys and lower foothill areas ' from the available winter range. The winter deer range in this area has therefore been restricted to a relatively small area of foothill country, and low elevation mountain slopes and benches. The deer herds have increased great~ during the past 25 years, possibly as a result of protection afforded them by the buck law, and reduction in the predator population. (The wintering of increased numbers of deer on limited areas has resulted in very undesirable con­ ditions.)(Heavy browsing has caused decrease in vigor and death of valuable browse plants. 1Higb winter mortality of deer also has result­ ed from malnutrition and secondary causes in foothill areas of high concentration, especially in winters of heavy snowfall and low temper- atures.) A deer management plan should be directed to maintain the produc­ tivity of the valuable forage species. Two phases in which information is needed are the relative palatability of the winter browse spbcies to deer, and the carrying capacity of different winter range types. There is also a need for an objective method of measuring browse utilization. Purpose of axoeriment This experiment was designed to obtain information as to the 2 utilization of the various forage species in three small. enclosed areas of winter deer range typical of that found in northern Utah under con­ ditione 9f known stocking of deer. and to determine the quantity of each forage species consumed by the deer. A second phase of the experiment vas to study the accuracy of the half-and-half sampling technique as a means of measuring winter browse use. 3 REVIEW OF LITERA'l'URE Several methods have been employed to study the food habits of deer and other browsing mammals. The botanical ana~sis of paunch contents has been used widely to determine the relative quantities of different forage species in the diet of ruminants in general, and deer in par­ ticular (DeNio 1938, Deen 1938, Carhart 194o, Nemanic 1942, and Rill and Harris ~948). In order to study the accuracy of this technique norris (1943) fed sheep measured quantities of various domestic and native forages, killed the sheep, and analysed the rumen contents both botanically and chemically. He found major differences between the known relative proportions of species in the forage consumed and the proportions obtained by stomach analysis. Norris accounted for this discrepancy on the basis of residues from previous feedings remaining in the rumen, and different forages de­ composing in the rumen at different rates. He concluded that the analysis of rumen contents was of limited value in a quantitative study of the diet of sheep,.- and similar conditions might be expected in the case of other ruminants. Cowan (1945) used stomach analysis in studying the food habits of the Columbian blacktail deer on Vancouver Island. Deer specimens taken for stomach analysis were shot towards the end of the morning browsing period before remastication had taken place. Succulent material of the spring and summer diet was effectively separated by flooding and decant­ ing in shallow trays. Fall and winter samples were washed, screened, and 4 separated by species. The quantities of each species vere measured by vater displacement. Covan reported that the difficulty of certain foods being more finely comminuted than others and passing through the screens vas not encountered in his vork. Observations of the feeding activity of grazing and browsing animals has been used to advanta&e by a number of workers vho have re­ corded the length of time spent by the animals feeding upon each species in order to evaluate its importance (Cory 1935. Dixon 1934, Snyder 19)6, Deen 19)8, and Nemanic 1942). Hubbard (1952) studied the relationship between the time spent by deer eating browse species and the weight of forage consumed. He found that although the two methods showed similar rankinge for the preferences of the species