Ecology of bighorn sheep of Wildhorse Island Flathead Lake Montana

Transcription

1 University of Montana ScholarWorks at University of Montana Graduate Student Theses, Dissertations, & Professional Papers Graduate School 1973 Ecology of bighorn sheep of Wildhorse Island Flathead Lake Montana John Wayne Matthews The University of Montana Let us know how access to this document benefits you. Follow this and additional works at: Recommended Citation Matthews, John Wayne, "Ecology of bighorn sheep of Wildhorse Island Flathead Lake Montana" (1973). Graduate Student Theses, Dissertations, & Professional Papers This Thesis is brought to you for free and open access by the Graduate School at ScholarWorks at University of Montana. It has been accepted for inclusion in Graduate Student Theses, Dissertations, & Professional Papers by an authorized administrator of ScholarWorks at University of Montana. For more information, please contact

2 ECOLOGY OF BIGHORN SHEEP ON WILDHORSE ISLAND FLATHEAD LAKE, MONTANA by JOHN W. MATTHEWS B.S., Washington State University at Pullman, 1967 Present in Partial Fulfillment of the Requirements for the Degree of Master of Science UNIVERSITY OF MONTANA 1973 chool l A j J J L j. h

3 UMI Number: EP37300 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. U M T Oiweftatkxi PuWishèng UMI EP37300 Published by ProQuest LLC (2013). Copyright in the Dissertation held by the Author. Microform Edition ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code ProQuest ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml

4 AC KNOWLEDGEMENTS This study was made possible by the cooperation of many people. Special thanks are due the family of the late R, Bourke MacDonald For the many services and information that were provided throughout the study. I would like to thank Dr. John J. Craighead, advisor and committee chairman, for initiating the study, providing many valuable suggestions, assistance, and guidance during all phases of the study. To D r s. L, E. Eddleman and R. R. Ream, I extend my thanks for valuable information and assistance in the formulation of the range study and review of the manuscript. Dr. B. W. O'Gara spent many hours reviewing manuscript drafts as well as providing suggestions for field work, For their advice and assistance, I extend my gratitude to the following: Drs. W. L. Pengelly and P. L. Wright, Mr. Kenneth Greer, Mr. Pat Patterson and fellow students John Hechtel, Charles Kay, and all who aided in the census work. The study was funded by the Montana Cooperative Wildlife Research Unit.* * Bureau of Sport Fisheries and Wildlife, Montana Fish and Game Depart ment. University of Montana, and Wildlife Management Institute Cooperating ; ii

5 TABLE OF CONTENTS Page LIST OF T A B L E S... LIST OF F I G U R E S... v vi Chapter I. I N T R O D U C T I O N... 1 II. STUDY A R E A... 4 Location and Description... 4 Climate... 6 Land Ownership and U s e... 6 III. M E T H O D S Range S t u d y Sheep S t u d y IV. R E S U L T S Range S t u d y Subtype Description V. D I S C U S S I O N M o r t a l i t y Mortality Factors N a t a l i t y Recommendations Management Options VI. S U M M A R Y LITERATURE CITED iii

6 Iv Page APPENDIX I Vegetatlonal Data for Wlldhorse I s l a n d la Vegetatlonal type Map of Wlldhorse I s l a n d Ib Vegetatlonal Subtypes with Corresponding Community Mapping Number, Acreages, and Dominant Forage Species. 52 Ic Plant L i s t Id Results of Subtype Sampling (by square foot plot).. 60 APPENDIX II Census and Activity D a t a I la Censuslng Map of Wlldhorse I s l a n d Ilb Six Dally Activity Patterns of Mountain Sheep on Wlldhorse Island APPENDIX III Mortality Data Concerning Mountain Sheep on Wlldhorse Island, Ilia Locations of Mountain Sheep Mortalities, Winter m b List and Location of Parasites Found In Winter-killed Rams from Wlldhorse Island, IIIc Host Parasite Data S h e e t s Illd Skull and Horn Weights, In Grams, of Winter-killed Rams from Wlldhorse Island, Ille Horn Measurements, In Millimeters, of Winter-killed Rams from Wlldhorse Island,

7 LIST OF TABLES Table Page 1* Average Maximum, Minimum and Monthly Temperatures (in degress Fahrenheit) for Flathead Lake Average Percent Cover (basal area) of Sampled Subtypes, in Square F e e t Summary of Acreages and Percentages of Plant Communities (classified by dominant species) by Percent Class Use Best Count Summary of Mountain Sheep on Wildhorse Island Sex and Age Distribution of Overwinter Mortality of Bighorn Sheep on Wildhorse Island Summary of Total Mortality of Bighorn Sheep on Wildhorse Island May, 1971-January, Sex and Age Specific Life Table Based on 67 Known-Age Mortalities of Mountain Sheep on Wildhorse Island Age Classification of Free Roaming Bighorn Rams by Annualation Count Bone Marrow Samples of Winter-killed Bighorn Sheep Rumen Analyses of Six Rams Found as Winter and Spring Mortalities Expressed in Percent Volume... 32

8 LIST OF FIGURES Fig. Page 1. Location of Wildhorse Island Abundance of Major Grazing Populations on Wildhorse Island 9 3. Vegetatlonal Use Map of Wildhorse I s l a n d Seasonal Distribution Map of Wildhorse Island Vegetatlonal Community Map of Wildhorse Island Lamb Production on Wildhorse Island During 1971 and Activity Patterns of Bighorn Sheep Based on Six Daylight Observations Sex and Age Specific Death Curve for Male and Female Bighorn Sheep of Wildhorse Island vi

9 Chapter I INTRODUCTION. Wildhorse Island, Flathead Lake, Montana, provides a situation in which two big game species. Rocky Mountain bighorn sheep (Ovis canadensis canadensis) and mule deer (Odocoileus hemionus hemionus), are found within the confines of an Island habitat. One horse and one mule are also present on the Island, Other mammals such as coyotes (Canis latrans), badgers (Taxidea taxus) and porcupines (Erethizon dorsatum) inhabit the Island, During an occasional harsh winter, ice allows some interchange with the mainland; however, this interchange is limited largely to deer and coyotes, Couey (Buechner, 1960) discussed seven transplants of Rocky Mountain bighorn sheep made in Montana, At least five of these appeared to have become established, one being on Wildhorse Island. The history of the bighorn sheep population on the Island is documented; a male and female, both yearlings, were introduced onto the Island in Their origin is uncertain; Ogren (1954) indicated that they were caught as lambs in the Mission Mountains and subsequently released on the Island. There is some feeling however, that the original stock may have come from the Sun River area (Pengelly, pers. comm.). In 1947, the Montana Fish and Game Department made one additional transplant of three adult females and three males (one 2 year old and two older males). Those animals introduced in the second

10 2 transplant were from Sun River Canyon (Ogren, Ibid.). At that time, the minimum size of the population was estimated at 12 animals (Ogren, Ibid.). The present herd, estimated at 240 individuals in 1972, grew from that small nucleus. During the same period, many other mountain sheep populations declined. Berwick (1968) documented the decline of the Rock Creek, Montana, sheep population. Morgan (1970) reported that bighorn sheep herds in the Challis, Idaho, area were on the decline- During the early 1950's, Smith (1954), found sheep populations to be on the increase in Idaho, but indicated that they were subject to periodic fluctuations. Buechner (1960) gave an extensive treatment of population fluctuations in the United States. He indicated that bighorn populations were drastically reduced in numbers from pristine times. A common denominator to the decline found by investigators in the past was usurpation of habitat by an encroaching civilization and competition from livestock on the remaining habitat. This is the third in a series of studies conducted through the Montana Cooperative Wildlife Research Unit on the bighorn sheep of Wildhorse Island. Ogren (1964) estimated that, at the end of his study in 1954, there were 90 sheep on the Island. Ten years later, Woodgerd (1964) estimated the population at 130. As the sheep increased, mule deer decreased; in 1954, the mule deer population was estimated at animals (Ogren, Ibid.). They declined to approximately 200 by 1964 (Woodgerd, Ibid.), and 75 were estimated to be present during my study in 1972.

11 3 As the Island population Increased, trapping was initiated to provide stock for transplanting into new areas. From 1954 to 1959, 47 sheep were removed in trapping operations (Woodgerd, op. cit.). Despite this additional "mortality", the population continued to increase; however, Woodgerd felt that the population was stable or declining slightly by Wildhorse Island is now under private management with limited summer home development occurring annually. Management guidelines are necessary to maintain the bighorn sheep and mule deer populations as well as the habitat. The present study was initiated to utilize the information contained in both previous studies and to gather additional data that would ultimately lead to a management plan. Specific objectives of the study were: 1. obtain an accurate census of the sheep and deer populations. 2. assess sex and age distribution of the sheep population. 3. describe population fluctuations in terms of natality and mortality. 4. map and quantitatively describe the habitat. 5. determine use of the habitat. 6. compare findings with those of earlier investigators.

12 Chapter II STUDY AREA Location and Description Wildhorse Island is located in the southwest corner of Flathead Lake approximately 10 airline miles northwest of Poison, Montana (Fig. 1). The Island is approximately 3.45 square miles in area and is characterized by a series of steep, parallel ridges. The highest point on the Island, 3,745 feet above sea level, is 853 feet above the summer level of the Lake. During the Wisconsin period of glaciation, Wildhorse Island was subject to erosion by the Flathead Glacier (Aiden, 1953). Glacial stria on the Island and surrounding areas indicate that the glacial movement was in a southwesterly direction. The sedimentary rock, characterized by the Ravalli group on Wildhorse Island, has a dip to the northeast at approximately 25 degrees (Alden, Ibid.). This inclined plane effect caused the glacial ice to ride up-and over the Island and break off on the south side, thus creating the broken cliffs found on the Island today. Soils developed from depositions of glacial till with little breakdown of parent material. These soils now support two basic plant communities; palouse prairie, occurring primarily on the south side of the Island, and timber on the north side (Appendix la). Variations in this general pattern arise from changes in edaphic and topographic factors.

13 Fig. 1. Location of Wildhorse Island

14 ROLLINS :;'l r*i«rvatten ILDm m L M O FLATHEAD LAKE INDIAN T 2 3 N»21W KESIftVATlON Scol> : U 2 ' - = I M Ü *

15 Climate The climate of the Island is greatly influenced by the surrounding Lake. Rainfall averages 15 inches per year. During winter, snow depths at Kalispell, the nearest recording station, range between 3 and 15 inches. The Flathead area averages between 100 and 120 frost-free days with high temperatures in the upper 90*s and lows in the subzero teens. Table 1 lists average temperatures by month for the surrounding area (U.S. Dept, of Commerce, Climatological Data 1970, 1971, 1972). Land Ownership and Use Wildhorse Island has been under private ownership since the turn of the century. Dr. J. C. Burnett accumulated the various private holdings and incorporated the entire Island into one ownership. During 1960, following Dr. Burnett's death, the Island property was placed in trust with the Union Bank and Trust Company of Helena, Montana. The property was appraised, bids were accepted for its sale, and was purchased by Mr. Bourke MacDonald of Missoula, Montana, who owned it through the period of this study. Early development on the Island included a resort complex on $ the east end, locally known as Hiawatha. This complex was built about 1910 (MacDonald, pers. comm.). For many years, the Island was used for raising hay, grazing cattle and horses, and as a dude ranch. the Island supported a population of feral horses and mules. Later, Trapping and winter mortality reduced them to the present one horse and one mule. Ogren (1954) estimated that utilization of the range was five times proper use. Following the decline of livestock, Woodgerd (1964) noted

16 TABLE 1 Average Maximum, Minimum and Monthly Temperatures (degrees Fahrenheit) for Flathead Lake Vicinity Month YEAR M M 0 N 1970a a Average Max. 1972b a a Average Min. 1972b , a a , Average 1972b a Big Arm b Poison

17 8 some improvement in range conditions but did not obtain quantified data. Past, heavy use by horses, as well as deer and bighorn sheep, is evident in the vegetational patterns on the Island. These features are primarily characterized by the abundance of cheatgrass (Bromus tectorum) and other invader species. The obvious lack of browse and conifer reproduction also attests to past abuse. Fig. 2 shows the abundance of horses, mules and deer on the Island since 1954, The mountain sheep population began with two sheep in Ogren (1954) found that use patterns displayed by bighorn sheep and horses on the Island varied from season-to season. During early spring when new growth appeared, horses grazed the lower elevations, concentrating on the south side, while bighorn sheep fed on the higher slopes and ridge tops. Based on relative volume of required herbage, the lower elevations received the greatest degree of use. Since 1956, when trapping and winter mortality reduced the horse herd, use patterns have changed, reflecting the change in numbers of horses and sheep. The deer population declined during this time, leaving the bighorn sheep as the prime user of the habitat. This change in numbers of primary users resulted in a shift of overuse from lower portions of the Island to higher ridges and cliffs (Fig. 3). Ewes and lambs remain on such areas well into the summer, further compounding overuse (Fig. 4). Such grazing pressure has created areas where utilization is approaching 100 percent of the vegetation (Fig, 3). On many sheep ranges, heavy use is limited to the winter range where sheep concentrate. Sheep generally leave wintering areas for

18 Fig. 2. Abundance of Major Grazing Populations on Wildhorse Island

19 loo Horses & Mules Deer a 205 Sheep r~ T93S ^ 195 S Year I "T---- IV75

20 10 other seasonal ranges (Geist, 1971). On Wildhorse Island, the entire habitat is subject to use throughout the year, depending on snow conditions and the degree of human activity. This situation puts an added burden upon the vegetation, principally during the growing season, when food reserves of plants are at their lowest and repeated cropping does not allow reserves to be restored.

21 Fig. 3. Vegetational Use Map of Wildhorse Island

22

23 Fig. 4. Seasonal Distribution Map of Wildhorse Island

24 ewes \ lambs lam bs iambs tombs W\ M ay June \// A M ay-july I MJJW inter-spring I HSummer-Fat I Summer December January F o il-w in ter

25 Chapter III METHODS Range Study A quantitative description of the vegetational communities of the Island was accomplished by vegetational mapping. Major vegeta tional types were delineated directly from aerial photographs. Once major types were determined by occular evaluation, they were checked by on site examinations and then the major types subdivided into eight distinct and easily recognizable subtypes based on dominant vegetation and past use (Appendix Ib). Private ownership precluded the establishment of permanent transects and exclosures. To obtain a representative sample of the subtypes, the square foot, plot method was used (Eddleman, pers. comm.). A series of random points were located on the type map and used as starting points for transects along which the square-foot plots were taken. The number of random points per subtype was based on its size but did not exceed 10; the minimum number was two. Each random point was comprised of 10 square-foot plots taken along a predetermined line at 10 pace intervals. Results of samplings appear in Appendix Id, Sheep Study To describe the population trend between 1964 and the present, it was necessary to obtain information on population size and structure. Private ownership prevented the use of marking techniques to identify 13

26 14 individual animals. To obtain these data, a course was established that covered the Island, could be traversed in one day and enabled an observer to count, sex and age sheep. In addition, censuses were conducted periodically with the aid of at least three additional observers. Each census was started from the same point and each observer plotted his observations on a map of the Island (Appendix Ila). Group composition, direction of movement, and time of sighting were recorded for each observation. Using this method, duplicate counts were minimal. Data collected during these periodic censuses, combined with that obtained from rounds made over the established course, yielded information on all parameters of the sheep population. Additional time was spent in an attempt to quantify some social behavior, primarily group integrity; however, on numerous occasions group sizes were in excess of 100 individuals and individual identification became extremely difficult. Observations made during this time yielded information concerning daily and seasonal activities (Appendix Ilb). This phase of the study was discontinued after efforts to obtain marked animals failed.

27 Chapter IV RESULTS Range Study- Extensive range reconniassance resulted in a vegetational community map (Fig. 5). major cliff areas. A total of 173 communities were mapped, excluding As each community was delineated on the map, a polar planimeter was used to calculate the area. Community sizes ranged from 0.70 to acres. Major cliff areas comprised acres. These plant communities were then grouped into eight basic subtypes which are described below. Average plant coverage, by percent basal area, for each subtype sampled is presented in Table 2. Subtype Description Open Ponderosa Pine (Pinus ponderosa) : Communities in this subtype were characterized by an overstory of mature ponderosa pine. Tree spacing was generally greater than 50 feet, which in most instances prevented a closed canopy. Understory vegetation consisted primarily of bunchgrasses. Bluebunch wheatgrass (Agropyron spicatum), rough festuca (Festuca scabrella), and to a lesser extent Idaho fescue (Festuca idahoensis) were the dominant species of the understory. Columbia needlegrass (Stipa columbiana) was found in pure stands on some sites. Other species occurring on this subtype include: Oregon grape (Berberis repens), arrowleaf balsamroot (Balsamorhiza sagittata) and a variety of other species in lesser abundance. See Appendix Ic 15

28 Fig. 5. Vegetational Community Map of Wildhorse Island.

29 y s a 4J I -m? >/ fortsi [ 1GRASSLAND m a j o r CUff AR:AS

30 for a complete list of species. Open ponderosa pine constituted 5.41 percent of the total acreage. 17 Closed Ponderosa Pine: This subtype, found in narrow drainages and northern exposures, was also characterized by an overstory of ponderosa pine, however, crown cover was typically closed. The dominant vegetation was generally pinegrass (Calamagrostis rubescen). Other species found in less abundance were: quackgrass (Agropyron repens). Canada bluegrass (Poa compressa), orchard grass (Dactylis glamerata), Oregon grape, and snowberry (Symphoricarpos albus). This subtype constituted percent of the Island area. Douglas-fir (Psuedotstuga menziesli) : Communities (10.24% of total area) within this subtype were dominated by an overstory of Douglas-fir. Forage production was low under the dense crown cover, but sheep commonly used this subtype for escape and protection from heat and storms. All stands, with the exception of numbers 76 and 90 (Appendix Ib), were young stands with closed canopies. All communities were found on northern exposures associated with rocky outcrops. Kentucky bluegrass (Poa pratensis) was the most common grass species. Mountain maple (Acer glabrum) also occurred here but was associated almost exclusively with cliffs and rocky outcrops. Oregon grape and snowberry were also present. Native Bunchgrass; This subtype was the most prevalent and extensive on the Island (33.55% of the total area). Both bluebunch wheatgrass and rough fescue occurred in pure stands; bluebunch wheatgrass occurred on dry ridges and open south-facing slopes; rough

31 TABLE 2 Average Percent Cover (Basal Area) of Sampled Subtypes in Square Feet Species Open Ponderosa Pine Ponderosa Pine Native Bunchgrass Dry Meadow Douglasfir Cheatgrass Old field Are of All Types Rock Bareground Moss & Lichen Litter , Basa Brte Feid Fesc Gear Poco Popr , Bere Agsp Stco Syal Dagl Caru Elgl Ager Acmi Pnpr H 00

32 19 fescue was almost always associated with north facing slopes and a high moisture regime. An important associate was Idaho fescue. On many areas, the latter species was drastically reduced or eliminated, primarily from over-grazing by horses and mules. Numerous "wolf plants" and hollow centers indicated an old age class of plant with very few younger plants interspersed, also implying past over-use. Sandberg bluegrass (Poa secunda), cheatgrass (Bromus tectorum), Japanese brome (Bromus japonicus) and Agrostis interupta were also present in varying abundance. Dry Meadow: Although not extensive (5.25% of the total area), dry meadow was considered an important vegetational subtype. These meadows were associated with depressions and drainage bottoms where an accumulation of both soil and water provided an optimum environment for forage production. The dry meadows remained "green" for extended periods and thus provided palatable forage into the summer, when other areas were supporting cured vegetation. Kentucky bluegrass, Canada bluegrass and Columbia needlegrass were dominant species occurring in these areas, but represent invaders or increasers on these sites, in indicating over-use. Cheatgrass: Overgrazing allowed the establishment of rather large areas dominated by cheatgrass (11.56% of the total area). Cheatgrass was used by bighorn sheep in the spring, prior to maturation, but provided little forage during the rest of the year. was sparse, and in some areas erosion pavement occurred. Ground cover This subtype was found on the dryer, south-facing slopes which were harsh

33 20 environments for colonizing native grasses. Under prevailing climatic conditions, the probability of extensive erosion is unlikely; however, some local erosion is occurring on denuded slopes. Of primary concern, however, is the elimination of more desirable forage because of the prevalence of this subtype. Bluebunch wheatgrass was a common co-domi- nant on these areas. Old Field: Vegetational patterns combined with man-caused treatments, in this case cultivation of 5.52% of the area, distinguish this subtype from those subtypes supporting a natural vegetational community. Floristic composition differed markedly from native communities. Some stands were dominated by a single species and others by a mixture. The predominant species were timothy (Phleum pratense), crested wheatgrass (Agropyron cristatum), orchard grass, and quackgrass. Other less abundant species were basin wildrye (Elymus cinerius), redtop (Agrostis alba), and Kentucky bluegrass. Juniper (Juniperus scopulorum) : This subtype was of little value to the sheep and deer populations. Only two areas were large enough to map; combined, they represent 1.63 acres. Native bunch grasses were the dominant understory vegetation; therefore, this small subtype was included within the bluebunch wheatgrass community for computation purposes (Table 3). Juniper was not limited to these two areas, but occurred as single trees in most of the timber communities and along the shores. All vegetational associations found in the above subtypes were then grouped into communities on the basis of the dominant species

34 21 within the subtype. Seven communities existed on the Island: rough fescue, bluebunch wheatgrass, old field, needlegrass-kentucky bluegrass, Douglas-fir, ponderosa pine, and cheatgrass. By combining the utilization map with the subtype map, amount and degree of use were calculated for the seven communities (Table 3). Sheep Study Based on periodic censuses, a minimum population of 240 bighorn sheep was estimated in the spring of 1971 (Table 4). The population was estimated at 205 sheep in the spring of 1972, 35 less than During this same period, the deer population increased from 55 in 1971 to 75 in the spring of This increase may have resulted from immigration when the Lake was frozen. Frequent inspection of lambing areas revealed the basic parameters of the lambing season. lamb was observed on May 3. During the spring of 1971, the first This lamb was less than 24 hours old and therefore. May 3 was considered the start of the lambing season in Lambing rapidly increased during the last 2 weeks of May and ceased by 10 June (Fig. 6). On that day, 78 lambs, accompanied by 128 ewes, were counted as they filed from one cliff across an open area to another cliff. A complete census of the Island revealed an additional 10 ewes; thus, a minumum of 138 ewes and 78 lambs were present on June 10, The first lamb of 1972 was observed shortly after its birth on April 26. Lambing was completed during the first week of June. On June 10, a complete census yielded 123 ewes and 15 lambs, a marked

35 TABLE 3 Summary of Acreages and Percentages of Plant Communities (classified by dominant species) by Percent Use Class 0-25% 25-50% 50-75% % Total of % of total Community Utilization Utilization Utilization Utilization area Acres % total Acres % total Acres %Î total Acres % total Acres Roughfescue Bluebunchwheatgrass Oldfield Needlegrass- Kentucky bluegrass Douglasfir Ponderosapine Cheatgrass , Total of class a % of total area 7, a) total area excluding major cliffs to

36 TABLE 4 Best Count Summary of Bighorn Sheep on Wildhorse Island Composition Seasons Census base ewes lambs rams total ewe:lamb:ram March-Apr a May June Oct.-Nov. * March-Aprll c 68 May-June b 15d 67 a Includes lambs of 1970 b does not include lambs of 1971 c lambs born In 1971 d lambs born In :56.2:67,7 100:50.4: :25.9: :12.2:

37 Fig. 6. Lamb Production on Wildhorse Island During 1971 and 1972.

38 0 Q lombi of 1971 lambs of 1972 Ui Jst Mau Mci' TRoi Mai Jui

39 25 reduction from the previous year (Fig, 6). The 15 lambs were associated with a group of 24 ewes. Mortality patterns were most striking on the Island. lambs died during the first 6 months of life in 1971 (11.5%). Nine During the following 6 months, 34 lambs died. This resulted in a spring count of 35 lambs or 43.6 percent of the original 78, Adult mortality for the winter of was a major factor in the decline from 240 to 205 individuals. During January and February of 1972, Big Arm Bay was frozen and prevented access to the Island. Sufficient thawing occurred by February 28 to permit access from Rollins. On that day, six dead rams were found within 2 hours. Continued surveillance of the Island during the following months revealed additional winter kills. Appendix Ilia shows the location of all winter- killed sheep found during the late winter and spring of A total of 58 carcasses were found during that period (Table 5) with 87 mortalities in the population during the period from May 1971 to January 1973 (Table 6). On the basis of 67 known age mortalities that occurred on the Island during the study, a sex and age specific life table was constructed (Table 7). Woodgerd (1964) tagged lambs during 1959, 1960, and 1961 on Wildhorse Island. Three ewes were observed with metal ear tags in the summer and fall of 1971 and one additional ewe appeared to have been tagged. Although the exact year of tagging cannot be determined, these animals would be between 10 and 12 years old. One ram collected during the study was tentatively aged at 10+ years by annualation

40 26 count and 64.9 percent of the remaining 94 rams were aged by annulation counts with the aid of a 15-45X spotting scope, revealing one additional ram of 10+ years of age. These six animals, 4 ewes and 2 rams all 10 years or older, represent 2.5 percent of the total population. A combination of insufficient forage, severe weather conditions, and a high populations of parasites apparently caused most of the mortality on the Island. A high percentage of the sheep found dying during the winter of were in an extreme state of malnutrition (Table 9). Of the 58 carcasses found during the winter of , 22.4 percent yielded bone marrow samples, 77.6 percent were either missing or too dehydrated for compression measurements. Of those animals measured only 2 (15.4%) showed compression of less than 15 percent. Only one sample (7.7%) had bone marrow considered normal for that time of year, with 5 percent compression and 80 percent fat content (Greer, 1968). One lamb was found in very poor condition with 44 percent compression. Rumens of six rams were full of vegetation (Table 10) suggesting they were not able to assimilate enough nutrients to maintain body functions. During March 1972, two rams were found dying and unable to move. Breathing was coarse and shallow, accompanied by extreme coughing with discharge of fluid (as much as several cups) from the lungs. Respiratory and digestive systems from these and 2 other rams were examined by David Worley (parasitologist). Appendix Illb lists parasites found and their location. Dr. Worley stated that "... these

41 TABLE 5 Sex and Age Distribution of Overwinter Mortality of Bighorn Sheep on Wildhorse Island Age in years Males Females Unknown sex Total % of Total Total % of total overwinter Mortality to VJ

42 TABLE 6 Summary of Total Mortality of Bighorn Sheep on Wildhorse Island, May 1971 January, 1973 SEASON May Nov Nov May 1972 May-Jan, 1973 Lambs of Lambs of Adults Total = 87 Total Mortality Percent of Total

43 TABLE 7 Sex and Age Specific Life Table Based on 67 Known age Mortalities of Mountain Sheep on Wildhorse Island Males Age Class X dx Ix Lx qx Tx ex , Females ,5 29

44 TABLE 8 Age Classification Of Free Roaming Bighorn Rams By Annualation Counts* Age In Years Number of Sheep Percent Of Total *Spotting Scope, 15-45X 30

45 TABLE 9 Bone Marrow Samples of Winter-killed Bighorn Sheep Cut Compressed Percent Age length length compression Comments JWM male n 2 100mm 74mm 26 dark red to light orange, limp, trans.* JWM male # mm 65mm 35 reddish orange, runny, limp, trans. JWM male H 4 100mm 73mm 27 light-orange to straw, limp, trans. JWM male j? mm 70mm 30 reddish orange, runny, limp, trans. JWM male # mm 95mm 5 80% fat, light grey (old), firm, opaque JWM male # mm 75mm 25 reddish orange, shrunken, limp, trans. JWM male # mm 58mm 42 pale orange, limp, trans. JWM male # mm 75mm 25 light orange, blood spots, trans. JWM male # mm 75mm 25. straw-salmon, blood spots, limp, trans. JWM male # mm 60mm 40 maroon red, limp, trans. JWM male # mm 73mm 27 salmon, firm opaque JWM female //I 6 30mm 26mm 10 light red, shrunken, limp, trans. JWM lamb //I 9 mo. 90mm 50mm 44 dark red, jelly-like, trans. *translucent w H

46 TABLE 10 Rumen Analyses of Six Rams Found as Winter and Spring Mortalities Expressed in Percent Volume Ram Number and Date of Death JWM M #4 JWM M in JWM M //lo JWM M //II JWM M #12 JWM M #21 Food Item Feb Feb March 1972 March 1972 Feb April 1972 Averag< Grasses Douglas-fir Ponderosa pine Oregon grape Balsamroot 3.11, tr Antenaria sp ,16.22 Snowberry Arenaria sp* Unidentified twigs Moss-like mat Fringed sage Miscellaneous mat , Bark Cer stium sp Sedges Achillea sp. tr Unidentified forb tr 00, tr Riceroot tr tr CO ro

47 33 sheep were Infected with the heaviest loads of stomach and intestinal roundworms that we have seen in a total of 14 bighorns.,. Parasite populations of this magnitude in domestic sheep would be considered a serious debilitating faction which would require immediate attention,** Lungworm infections were low, although they may have contributed to the contraction of the pneumonia found present by the Veterinarian Clinic at Bozeman, An extensive examination of all winter kills revealed few external parasites. A small number of ticks (Dermacentor andersoni) were found. Predation could not be accurately measured. On September 17, 1971, three coyotes were observed in a group on the Island. Once in early July, 1971, a single coyote approached two groups of sheep, one group of six mature males and one group of six ewes with lambs. The rams were bedded and facing away from the coyote. Only two rams turned their heads to watch the coyote approach, but none of them stopped ruminating or got to their feet. The coyote approached within 20 feet of the ram group as he proceeded toward the ewes and lambs. The lambs and five of the ewes fled toward the cliff, 100 feet distant. The lone female remained at the feeding site and watched the coyote approach. The coyote was within 30 feet of the ewe when he stopped. At that time, the ewe advanced several steps and stopped. The coyote remained stationary for approximately 30 seconds then moved into the nearby timber. Ravens (Corvus corax), bald eagles (Haliaeetus leucocephalus) and golden eagles (Aquila chrysaetos) were observed on the Island.

48 34 Frequent sightings were made during the lambing season, but none of these birds were seen on a kill or attempting to make one. A pair of goshawks (Accipiter gentilis) nested on the Island but were not a threat to the sheep population. Ravens frequented the Island year- round but were never seen on a carcass. Ewes were aggressive protectors of their young. On one occasion, I approached close enough to touch a young lamb as it lay motionless. When the lamb bleated loudly, the ewe charged over the hill and confronted me at about 5 feet. She remained between me and the lamb until the lamb had reached safety, then she retreated, turning frequently to watch me. Poaching occurred on the Island but was difficult to assess. In December 1971, an individual was observed loading a ewe and lamb into a boat. A ram, approximately 8-years-old (aged by tooth wear), was found cached under a pile of brush with the horns and cape removed. One other ram, easily recognized, was missing in March, 1972, and I believe it was poached. Accidents were infrequent but two lambs were observed falling from cliffs. One fell 30 feet to a talus slope, and appeared to have sustained a spinal injury. The injured lamb was observed 2 weeks later but disappeared soon after that. Quantification of activity patterns proved difficult without marked animals. Limited observations indicated that periods of relative inactivity occurred from 0730 to 1030 and again from 1800 to 1900, As Fig. 7 indicates, some sheep are active during all daylight hours. The relationship of activity to sunrise and sunset is illustrated in

49 35 Appendix lib. Blood (1963) found activity peaks occurring at 0830, 1230, and ; periods of low activity occurred from 1030 to 1130 and again from 1330 to 1430, Berwick (1968) found a similar pattern for sheep of Rock Creek, Montana,

50 Fig. 7. Activity Patterns of Bighorn Sheep Based on Six Daylight Observations

51 y/////à [///// A v z z M ^ ^^ / / / /, Z V/7///V Â I I o 1 I 1 o n o I ZZZZ] 7 A r / 7 / y g I dljhs do M S W n N

52 Chapter V DISCUSSION During the winter of , counts of sheep on Wildhorse Island indicated that this population had reached an all time high* An investigation was initiated to document a probable rapid decline. In the spring of 1971, prior to lambing, 240 sheep were counted on Wildhorse Island. by Woodgerd in 1964, This was a substantial increase for the 130 found During that 7 year period, numbers of mule deer, horses and mules declined. Classification of rams indicated 50.8 percent of the male population to be 3-and 4-years-of-age, suggesting that the population increase since 1964 occurred within the last 3 or 4 years ( ). By spring of 1972, the sheep had declined to 205 animals, a population reduction of 15 percent. Mortality Mortality varied greatly during the 14 months of the study. In the spring of 1971, only two carcasses were found; this suggested negligible mortality during the previous winter. During and following the winter of , a total of 58 carcasses was found. Animals 1.5 years old and older constituted percent (35) of the winter kills; those animals in the 0.5 year age class comprised percent of the overwinter mortality. Table 7 illustrates the patterns of mortality that occurred in the sheep population. The calculated mean life expectancy for male 37

53 38 and female sheep was 2.91 and 2.70 years, respectively. Bradley and Baker (1967) calculated mean life for desert bighorns at 2.95 and 2.56 years for males and females, respectively. On Wildhorse Island, male sheep had an average first year, age-specific mortality rate of 0.205, while female sheep of this same age class had a rate. Age- specific death-rate of females, older than 1 year, were significantly lower than those of similarly aged males (Fig. 8). Following the first year of life, average life expectancy increased for female sheep. Table 5 reveals that mortality of males 1.5 years old or older was almost 50 percent higher than that of females of the same age. Sixty- one percent of the mortality suffered by males older than 1.5 years was in the 3.5 and 4.5-year-old age classes. Higher mortality in those age classes was partially a function of the number of those individuals found in the population (Table 8). Differential mortality resulted in a high ratio of ewes to rams during June: 1971, 100:68; 1972, 100:54 (Table 4). There was no significant change in ewe:ram ratios from June to winter, (100:69). Mortality Factors Two primary factors causing extensive mortality were shortages of nutritious forage and high incidence of internal parasites. My data showed a forage depletion situation. Sampling of 32 plant communities showed that rock, bare ground, moss and lichen, and litter covered percent of the ground per plot. All grasses combined averaged only 3.92 percent ground cover per plot. The remaining ground cover consisted primarily of forbs, Occular analysis

54 39 and sampling both revealed a conspicuous lack of browse. Only Oregon grape was common. Thus, sheep derived the bulk of their nutrient requirements from cured grasses during the winter months. Although grasses were limited In quantity, forage production appeared to be adequate for the sheep during "normal** winters. Analyses of the contents of six rumens, collected during winter and spring of 1972, yielded additional evidence that the sheep depended on grass and grass like plants (Table 10). The winter diet of sheep on Wildhorse Island was percent grasses, 2.09 percent forbs, and 2.09 percent browse. Conifers and sedges constituted 4.82 and 0.03 percent of the diet, respectively. Blood (1967) and Honess and Frost (1942) found that bighorn sheep In British Columbia and Wyoming utilized grasses at the rates of 72.0 and 48.3 percent, respectively; forbs at 4,0 and 29.6 percent and browse at 24.0 and 19.4 percent. Barrett (1964) Indicated that desert bighorns consumed 76 percent grasses, 4 percent forbs, and 20 percent browse. Bighorns in Yellowstone National Park used 61.4 percent grasses, 17.2 percent forbs, and 21.5 percent browse during the winter (Oldemeyer, 1966). The Sun River herd of Montana consumed only 36 percent grasses during the winter compared to 86.5 percent during fall; consumption of forbs Increased for 8.9 In fall to 21.0 percent In the winter, and browse from 1.9 to 43.0 percent (Schallen- berger, 1965). These studies Indicated that sheep generally utilized grasses In the fall when this forage contained Its greatest nutritional value. They shift to browse In winter when grasses have a relatively low nutritional value, Knocke (1968) found that levels of crude protein In browse species ranged 5.1 to 9.5 percent during winter

55 Fig. 8. Sex and Age Specific Death Curve for Male and Female Bighorn Sheep of Wildhorse Island.

56 -Q MALES 1000 FEMALES 100 Z o o o Ù. Wl Z 10 V- < Ul O AGE IN YEARS

57 41 months* These levels are two to three times as high as crude protein levels which are found In grasses during the same months. I conclude that the lack of browse on Wildhorse Island Is a major factor limiting further growth of the sheep population. Large numbers of Internal parasites compounded the nutritional stress of sheep wintering on a low protein diet. The numbers of parasites (Helminthes : Marshallagla. Ostertagla, Trlchostrongylus, Nematodlrus» Trlchurls. and Chabertla) found In the sheep utilized available nutrients already In short supply. A low incidence of lung- worm (Frotostrongylus stllesl) Infestation was found In all examined lungs (Appendix IIIc). With the sheep under stress, these low numbers may have been more debilitating than their numbers suggest. Poaching and predation also contributed to mortality. Poaching was greatest during November and December when the Island was uninhabited, and the Lake was not yet frozen. More rams were poached than ewes, possibly because rams, preoccupied with rutting activity, were easily approached, and potential Income from record class rams was high. Following the rut, groups of rams congregated along the north shore, making It relatively easy to poach without detection since this portion of the Island Is not subject to extensive surveillance from the mainland. At least four sheep were poached during November and December of Predation was not easily quantified. Several species, capable of preying on sheep, were present on the Island. Poison baits (1080) placed on the Island In 1970 reduced the coyote population to three. They were not observed preying on sheep. Other predators on the Island were bald and golden eagles, ravens and

58 42 badgers. During the 14 months of this study, no direct evidence of predation was found from any of the listed predators. Two lambs were involved in accidents. In both cases, they fell from cliffs and sustained injury. None of the sheep found dead on the Island were considered victims of accidents, although Morgan (1970) found accidents a significant mortality factor in Idaho. In June and July of 1971 following lambing, four ewes were observed with porcupine quills in their faces, necks or forelegs. One had three quills in her eyelid that closed the eye. Such a condition could lead to a fatal accident or infection. Old age was not considered an important mortality factor, but was a factor in other years (Woodgerd, 1964). Natality In the spring of 1971, a total of 78 lambs were produced by 138 ewes. Early survival was high, 88.5 percent during the first 6 months of life. However, the severe winter of reduced the original 78 to 35. Reproduction was poor in the spring of Breeding activity and success appeared normal the previous fall. Therefore, I felt that the low lamb crop of 1972 was a result of losses either before or shortly after birth. Severe nutritional stresses during the previous winter undoubtedly resulted in less vigorous lambs and reduced milk production. Lambing began and ended at approximately the same time both years, but the lamb crop of 1972 was 81 percent lower than that of Ogren (1954) noted post lambing ratios ranging from a high

59 43 of 100:91 to a low of 100:59 on Wildhorse Island. Recommendations Although some basic information was gathered on the sheep and deer populations, additional information should be obtained in the future. Private ownership precluded range production and utilization measurements; thus, I was unable to determine the population levels of deer and sheep that the Island could support during normal winters The large die off occurring in indicated that an upper limit was approached. The following recommendations would aid in preserving the sheep and deer populations as well as the Island habitat. 1. Estimate carrying capacity of the range by establishing range transects to determine plant productivity and utilization. 2. Determine food habits and correlate with forage nutrient values determined by laboratory analyses and digestion studies. 3. Continue studies of population dynamics, 4. Manage the sheep and deer populations to keep them in balance with the habitat. Management Options Based on the management objectives of the Island developers several options are available for management of the sheep population. These options are based on the assumption that the above recommendations are followed. A. Natural Population Regulation. This option is essentially

60 44 operative on the Island at the present time; however, no further reduction of predators should occur. Under this system, periodic mortality such as that which occurred in should be expected. Key foraging areas should be closely observed to insure that they are not over utilized and that present areas of over-use do not increase in size. If such an increase begins, proper steps should be taken to reduce the sheep and deer populations. This could be effected by either a transplanting program or a permit-fee hunting season. B. Management for Trophy Rams. Under this option, record class rams would be the desired goal. The population would be maintained at or below carrying capacity to insure rapid growth of the remaining individuals. Population levels could be maintained by manipulation of the female segment of the population. This can be achieved by transplanting or issuing limited ewe permits with supervised harvesting under a fee system. The harvesting of trophy rams would also be achieved by a permit-fee system. The number of rams that could be produced would depend on the size of the population that the Island could support. C. Maximum Productivity. Under this plan, the sheep population structure would remain similar to a natural population; however, the number of individuals within each age class would be maintained at a low level. This system

61 could provide an excellent stock for transplanting into new ranges or the desired harvest could be achieved by a permit fee system. 45

62 Chapter VI SUMMARY AND CONCLUSIONS Between 1964 and 1971, mountain sheep on Wildhorse Island increased from 130 to 240 animals while mule deer decreased from approximately 200 to 55. By the summer of 1972, the sheep population was reduced to 205 and the deer herd had increased to 75. During the 14 months of the study the sheep population reached a high of 309 individuals, including lambs of the year, during the summer of Range surveys indicated that utilizations of areas frequented by sheep had reached critical levels. Density of sheep also created favorable conditions for the spread of intestinal parasites. The effects of these two factors were of primary importance in reducing the size of the population, when combined with severe environmental stresses of snow and subzero temperatures. Prior to the winter of , lamb production and survival were high. Following this severe winter, lamb production was very low and survival was negligible. Adult mortality during this winter was significantly higher than both the previous and following years. This situation indicates that the sheep population is approaching a maximum size. During the recent die off, lack of forage and a heavy load of intestinal parasites resulted in mortality when weather conditions reduced the vigor of the sheep. If the population continues to 46

63 47 Increasey these two factors may become independent of environmental stresses and reduce the sheep herd. Other forms of mortality were not considered to be important factors in reducing the sheep populations,

64 LITERATURE CITED Alden, W.C Physiography and glacial geology of western Montana and adjacent areas. Geological Survey Professional Paper 231, Washington. U.S. Government, Printing Office. 200pp. Barrett, R.H Seasonal food habits of bighorns at the Desert Game Range, Nevada. Trans. Desert Bighorn Council, 8: Berwick, S.H Observations on the decline of the Rock Creek, Montana, population of bighorn sheep. M.S. thesis, Univ. of Montana, Missoula. 245pp. Blood, D.A Some aspects of behavior of a bighorn herd. Canadian Field Naturalist. 77(2): Food habits of the Ashnola bighorn sheep herd. Canadian Field Naturalist. 81(1): Bradley, W.G. and D.P. Baker Life tables for Nelson bighorn sheep on the Desert Game Range. Trans. Desert Bighorn Council. 11: Buechner, H.K The bighorn sheep in the United States, its past, present, and future. Wildl, Mono. No pp. Greer, K.R A compression method indicates fat content of elk (wapiti) femur marrows. J. Wildl. Mgmt. 32(4): Honess, R.F. and N.M. Frost A Wyoming bighorn sheep study. Wyoming Game and Fish Dept, Bull. 1, 127pp. Knocke, K.G The ecology of the Rattlesnake Creek, Montana, mule deer winter range. M.S. thesis, Univ. of Montana, Missoula. 152pp. Morgan, J.K Ecology of the Morgan Creek and East Fork of the Salmon River bighorn sheep herds and management of bighorn sheep in Idaho. Research Completion Report, Idaho Fish and. Game Dept,, Project W-142-R pp. Ogren, H.A Population study of bighorn sheep on Wildhorse Island. M.S. thesis, Univ. of Montana, Missoula. 77pp. Oldemeyer, J.L Winter ecology of bighorn sheep in Yellowstone National Park. M.S. thesis, Colorado State Univ., Fort Collins. 107pp. 48

65 Schallenberger, A.D Food habits, range use, and interspecific relationships of bighorn sheep in the Sun River area, west central Montana. M.S. thesis, Montana State Univ., Bozeman. 44pp. Smith, D.R Bighorn sheep in Idaho, its status, life history, and management. Idaho Fish and Game Dept. Wildl. Bull. No pp. U.S. Dept, of Comm. Climatological Data. National Oceanic and Atmospheric Admin Woodgerd, W Population dynamics of bighorn sheep on Wildhorse Island. J. Wildl. Mgmt. 28(2):

66 Appendix I VEGETATIONAL DATA FOR WILDHORSE ISLAND 50

67 Appendix la Vegetational Type Map of Wildhorse Island.

68

69 Appendix Ib Vegetation 21 Subtypes with Corresponding Community Mapping Number, Acreages, and Dominant Forage Species. 52

70 53 Dry Meadow Old Field Cheatgrass Communi Cy Dominant Community Dominant Community Dominant No. Acres Species No. Acres Species No. Acres Species Stco Agre 3 2,09 Brte Popr Phpr Brte Popr Popr, Elgl Brte Popr Agcr Brte Stco Agre Brte Agre Agcr Brte Stco Agcr Brte Popr Popr Brte Popr Dagl, Agcr, Brte Agal Popr Dagl Brte Popr Brte Agal Brte Poco Acres Brte Poco 5.52% Brte Popr Brte Stco Brte Caru Brte Stco Brte Popr Brte Popr Brte Brte Brte Acres Brte 5.25% Brte Brte Brte Brte Brte Brte 254,99 Acres 11.56%

71 Open Pipo Community No. Acres Dominant Species Psme Community No. Acres Dominant Species Jasc Community No. Acres Dominant Species Pipo Community Dominant No. Acres Species Popr, Fesc Agsp, Fesc, Brte Fesc Agsp, Fesc, Fesc, Agsp Agsp Agsp, Brte, Agsp, Popr Agsp, Agsp Stco Agsp Fesc Acres 5.41% Caru Fesc Agsp Fesc Agsp Agsp Fesc Agsp Basa Feid Caru.47 Psme Psme 4.18 Psme Elgl, Here Psme Psme 3.49 Popr 2.79 Psme.70 Psme 4.18 Agsp 2.09 Psme Acres 10.24% Agsp.70 Agsp 1.63 Acres.07% Caru Caru Popr, Caru Agsp, Bere Popr Caru Caru Caru Caru Caru Caru Popr Caru 104 Cliff Agsp Brte Popr Caru Popr Caru Caru Caru Stco Poco Caru Caru Acres 26.78%

72 Bunchgrass 55 munity Dominant Community Dominant No. Acres Species N o. Acres Species Agsp, Cesc Agsp Agsp Agsp Agsp Agsp Fesc Agsp Agsp Agsp Agsp Agsp Fesc Fesc Agsp Agsp Agsp, Feid Agsp, Fesc Fesc Agsp Agsp Agsp Agsp Fesc Fesc Agsp Agsp Fesc Agsp Acres Fesc Agsp 33.55% Agsp Cliff Areas Agsp Agsp Acres Agsp 1.62% of total Agsp Fesc Total Area Fesc, Feid Acres Agsp Agsp Agsp Agsp Agsp Fesc Fesc Agsp Agsp Agsp Fesc Agsp Agsp Agsp Fesc Fesc Agsp

73 Plant List Scientific Name Trees Pinaceae Juniperus scopulorum Pinus ponderosa Psuedotsuga menziesii Salicaceae Populus trichocarpa Shrubs Aceraceae Acer glabrum Berberidaceae Berberis repens Caprifoliaceae Symphoricarpos albus Compositae Artemisia frigida Cornacea Cornus Stolonifera Rosaceae Amelanchier alnifolia Prunus spp. Rosa spp. Forbs Asclepiadaceae Asclepias speciosa Boraginaceae Lappula redowski Lithospermum ruderale Campanulaceae Campanula rotundifolia Common Name Juniper Ponderosa pine Douglas fir Cottonwood Mountain maple Oregon grape Snowberry Fringed sage Red osier dogwood Serviceberry Cherry Rose Milkweed Stickseed Cromwell Harebell Abbreviations Jusc Pipo Psme Potr Acgl Bere Syal Arfr Cost Amal PRU Rose Assp Lare Liru Caro 56

74 Plant List (continued) 57 Forbs continued Caryophllaceae Arenaria conjesta Cerastium arvense Crassulaceae Sedum stenopetalum Field chickweed Stonecrop Arco Gear Ses t Compositae Achillea lanulosa Achillea millefolia Agoseris retrorsa Antenaria lanata Antenaria rosea Arnica cordlfolia Arnica latifolia Balsamorhlza saglttata Circium vulgare Chrysopsis villosa Erigeron caespitosus Erigeron pumalis Filago arvense Taraxicum officinale Tragopogon dubius Yarrow A d a Yarrow Acmi Agre Antenaria Anla Pussytoes Anro Heartleaved arnica Arco Arnica Aria Arrowleaf balsamroot Basa Bull thistle Civu Hairy golden aster Chvi Tufted fleabane Erca Fleabane Erpu Field fluffweed Fiar Dandelion Taof Salsify Trdu Cruciferae Camelina microcarpa Camelina sativa Descuriana sophia var, sonnei Mus tard Mustard Mustard Garni Casa Deso Hydrophyllaceae Phacelia linearis Linear-leaf phacelia Phli Iridaceae Sisyrinchium sarmentosum Liliaceae Allium cernuum Brodiaea douglasil Calochortus nuttallii Fritillaria pudica Smilacina racemosa Zygadenus gramineus Leguminosae Erodlum cicutarium Lupinus spp. Oxytropis spp. Blue eyed grass Nodding onion Wild hyacinth Sego lily Yellow bell False solomonseal Death camus Stork's bill Lupine Loco Sisa Alee Brdo Canu Frpu Smra Zygr Erci LUP OXY

75 Forbs continued Orchidaceae Goodyera spp Plant List (continued) Rattlesnake plantain GOO 58 Polemoniaceae Polemonium pulcherrimum Portulaceae Lewisia rediviva Primulaceae Dodecatheon pauciflorum Ranunculaceae Delphinium bicolor Rosaceae Fragaria vesea Geum triflorum Rosa spp. Saxifragaceae Heuchera cylindrica Lithophragma glabra Ribes cereum Ribes setosum Saxifrage spp. Scrophulariaceae Castilleja sulphurea Orthocarpus tenuifolius Penstamin spp. Jacob s ladder Bitterroot Shooting star Low larkspur Strawberry long-plumed avens Rose Alum root Woodlands tar Squaw currant Squaw currant Saxifrage Yellow paintbrush Owl *s clover Penstamin Popu Lere Dopa Debi Frve Getr Rose Hecy Ligl Rice Rise SAX Casu Orte PEN Umbelliferae Lomatium simplex Narrow-leaf lomatium Losi Grasses Gramineae Agropyron cristatum Agropyron repens Agropyron spicatum Agropyron trachycaulum Agrostis alba Agrostis interupta Bromus.japonicus Brcmus marginatus Bromus tectorum Calamagros tis rubescens Dactylis glomerate Elymus cinerius Crested wheat grass Quack grass Bluebunch wheatgrass Slender wheatgrass Redtop Japanese brome Awnless brome Cheatgrass Pinegrass Orchardgrass Basin giant rye Agcr J Agre Agsp" Agtr Agal'- Agin Brjai Brma Brte' Caru ' Dagl' Elci

76 Forbs continued Plant List (continued) 59 Elymus glaücus Festuca idahoensis Festuca occidentalis Festuca scabrella Koelaria cristata Phleum pratense Poa ampla Poa compressa Poa pratensis Poa secunda Stipa Columbiana Stipa williamsii Smooth wild rye Idaho fescue Rough fescue Prairie junegrass Timothy Big bluegrass Canada bluegrass Kentucky bluegrass Sandberg bluegrass Columbia needlegrass Williams needlegrass Elgl^ Feid^ Feoc Fesc ^ Kocr Phpr ^ Poara Poco/ Popr^ Posey Stco^ Stwi Junaceae Juncus balticus Wirerush Juba

77 Appendix Id Results of Subtype Sampling (by square foot plot)

78 FOREST TYPE open Pipo Subtype SPECIES X cv X cv X cv Aver, for all Subtypes Rock _ Bareground * Moss & Lichen Litter Basa Brte Feid Fese Gear Poco Popr Bere Agsp Stco Syal Dagl Caru Elgl Agcr Acmi Phpr

79 FOREST TYPE Closed Pipo Subtype Subtvpe No, SPECIES X cv X cv X cv X cv X cv Aver, for all Subjects Rock Bareground Moss & Lichen Litter , Basa Brte Feid , Fesc Gear Poco , Popr Bere Agsp Stco Syal Dagl Caru Elgl Agcr Acmi Phpr

80 Psme Subtype 105 FOREST TYPES SPECIES X cv Rock Bareground - - Moss & Lichen Litter Basa - - Brte - - Feid - - Fesc - Gear - - Poco - - Popr Bere - - Agsp - - Stco - - Syal - - Dagl - - Caru - - Elgl - - Agcr - - Acmi - - Phpr ON N)

81 Native Bunchgrass Subtype GRASSLAND TYPES SPECIES X cv X cv X cv X cv X cv X cv Rock Bareground Moss & Lichen , Litter Basa Brte Feld Fesc Gear Poco Popr Bere Agsp Stco Syal Dagl Caru Elgl Agcr Acmi Phpr o\ w

82 Native Bunchgrass Subtype continued Subtvpe No GRASSLAND TYPES SPECIES X cv X cv X cv 161 Aver, for ail Subtypes Rock Bareground Moss & Lichen Litter Basa Brte Feid Fesc Cear Poco Popr Bere Agsp Stco Syal Dagl Caru Elgl Agcr Acmi Phpr O'

83 GRASSLAND TYPES Dry Meadow Subtype SPECIES X cv X cv X cv X cv Aver, for all Subtypes Rock _ Bareground Moss & Lichen Litter Basa * - Brte Feid Fesc Cear Poco Popr ,03 Bere Agsp Stco Syal Dagl Caru Elgl Agcr Acmi Phpr VI

84 Brte Subtype GRASSLAND TYPES SPECIES X cv X cv X cv X cv X cv X cv Rock Bareground Moss fit Lichen Litter 55, Basa Brte Feid Fesc Cear Poco Popr Bere " Agsp Stco Syal Dagl Caru Elgl Agcr " Acmi Phpr O' O'

85 Brte Subtype SPECIES X cv X cv GRASSLAND TYPES Aver, for all Subtypes Rock , Bareground Moss & Lichen Litter Basa Brte Feid Fesc Cear Poco Popr Bere Agsp Stco Syal Dagl Caru Elgl Agcr Acmi Phpr Ov

86 Appendix II Census and Activity Data 69

87 Appendix lia Censuslng Map of Wildhorse Island

88 Y'

89 -W&'.# -ïk-'.'iv %A/, 1 >./, 1-V'

90 Appendix Ilb Six Daily Activity Patterns of Bighorn Sheep on Wildhorse Island

91 140 I I b e d d in g s u n r is e 0445 s u n s e t 3033 fe e d in g a n d m o v in g June 30, I ISOO TIME OF DAY

92 140 L l bedding sunrise 0449 sunset 3033 feeding and moving July 7, &Ui UJ X M Ik 0 «yj s 3 Z TIME OF DAY

93 140 L J bedding sunrise 043* sunset 3027 feeding and moving July 15, & w HI 60 la 0 fit HI m g 40 3 Z 20 5 N S N 13 n \ 17 \_ N _ , T IM E OF DAY

94 140 I I bedding sunrise osis sunset IS 04 feeding and moving October 6, Ik 0 ec III a s = 40 \ \ ISOO TIME OF DAY

95 K> O NUMBER OF SHEEP t g 8 M O z Z3!! o 10» 2 = E3 s I

96 140 I {bedding feeding ond moving November 14, 1971 sunrise 073a sunset a II I X V) 60 Ik o Of 49 III g 3 z 40 \ \ 20 \ \ ISOO TIM E OF DAY

97 Appendix III Mortality Data Concerning Mountain Sheep on Wildhorse Island,

98 Appendix Ilia Locations of Mountain Sheep Mortalities, Winter

99 (2A) rrimuc OEffR Cf

100 d*c»i) muwc _ o*