The number of desert bighorn sheep (Ovis canadensis mexicana) in Pusch Ridge Wilderness (PRW), Santa Catalina Mountains, Arizona has declined to between 50 and 100 animals. Sheep have restricted movements to the southwest corner of PRW. I developed a model based on nitrogen (N) content of forage and forage quantity to measure seasonal changes in nutritional carrying capacity of sheep use areas in PRW. Forage based estimates of animals numbers were greater for April to September than for October to March. My study suggests that forage is not limiting desert bighorn sheep in PRW and illustrates the potential to support more desert bighorn sheep in PRW than the current population. Seasonal fluctuations in range productivity should be examined in relation to human disturbances proximal to desert bighorn sheep habitat and fire management programs for PRW.

Many prey species exhibit antipredator responses in the presence of humans. These responses may lead in turn to behavioral modification and spatiotemporal avoidance strategies that may have implications for long term population dynamics. Our research was developed to measure the potential effects of backcountry recreation on the behavior and distribution of desert bighorn sheep in the Pusch ridge Wilderness Area (PRWA), Arizona, USA. Human use of the PRWA was quantified across the study site using real time observer field counts and modeled use metrics derived from motion activated trail cameras (n=15) placed on six US Forest Service (USFS) trails. We conducted 113 behavioral observations at multiple spatial scales from February of 2015 through May of 2016 to quantify female bighorn activity budgets and responses to human interaction. Bighorn behavior was characterized in a generalized linear model (GLM) to examine how human use and environmental covariates affect changes in the frequency of behaviors within the bighorn activity budget. Our models indicate that interactions between bighorn and humans are complex. An increase in human activity in the PRWA correlates inversely with bighorn time spent grazing. As a potential trade off bighorn significantly increased the frequency of time bedded. These results suggest that bighorn behavioral responses to human activity may carry costs associated with avoidance, however, behavioral analysis alone is not enough to measure the extent of such costs. This research has management implications where multiple use and high levels of human activity have the potential to negatively influence the behavior of wildlife species.

No description available.

No description available.

The seasonal development and yields of four major plant communities, of the important winter ranges of California bighorn sheep (Ovis canadensis californiana Douglas) in the Ashnola region, and their relation to basic climatic factors, were studied from May 1967 through December 1968. The four communities were: 1) Da bunch grass community dominated by Agropyron spicatum, 2) a sod grass community dominated by Poa pratensis, 3) a tree understory community dominated by Calamagrostis rubescens and 4) a half-shrub community dominated by Artemisia frigida. The climatic variables measured were: ambient air temperature, precipitation, including snow, evaporation and wind. Run-off, soil moisture and soil temperature were also measured. To reduce climatic variations between communities, all study sites were located at approximately the same elevation and were close to one another. Virtually all forage production in the four communities, in the growing seasons of both 1967 and 1958, occurred before the end of July. After this time, due to shattering, leaching and decay, decreases in herbage weights, ranging from 23 to 35 percent occurred by autumn, and further losses, ranging from 7 to 36 percent occurred over winter. The mean growth rates were essentially the same in the two years, but the cessation of growth two weeks earlier in 1968, resulted in lower production than in 1967. The dates spring growth commenced coincided closely with the dates that mean daily temperatures rose to 42 degrees Fahrenheit, whereas the dates growth ceased coincided closely with the dates that available soil water was exhausted. Both ambient air temperatures and soil temperatures remained favourable for growth until early autumn. The length of the growing season is the main factor determining net productivity of the Ashnola bighorn winter ranges; temperatures determine the beginning of the season and soil moisture deficits terminate the season. Moreover because the growing season is relatively short, climatic influences are important factors determining how much of the forage produced will remain potentially available for overwintering bighorn. / Land and Food Systems, Faculty of / Graduate

The effect of seasonal cattle grazing on a newly reintroduced population of California bighorn sheep (Ovis canadensis californiana) in Big Cottonwood Canyon, Idaho, was studied. The hypothesis that bighorn sheep avoid cattle was tested. The issue of avoidance between bighorn sheep and livestock is arguable. Some studies have found that bighorn sheep avoid cattle while others have found no response of bighorn sheep to cattle. Evidence was found to document the avoidance of cattle by bighorn sheep. The size of the bighorn's home range and core area decreased with the movement of cattle into areas of high bighorn use. As cattle were moved into bighorn core areas, sheep responded by relocating. Bighorn sheep decreased their distance to escape terrain as cattle moved closer. The level and location of human disturbance on the study area did not have any effect on bighorn sheep movements or how sheep used the habitat. The severity of response observed is in marked contrast with the response of established bighorn populations to cattle. I suggest that newly reintroduced bighorn sheep are extremely sensitive to disturbance as a result of relocation trauma. Sensitivity may diminish over time.

We determined the diet contributions of grasses, forbs and shrubs for three herds of bighorn sheep along the Wasatch Front, Utah using stable isotope techniques and determined the electivity values for different forage species for four herds. Forbs were generally the most common forage eaten across all herds while shrubs were the least used forage resource. The Provo Peak and Mount Nebo herds used grasses, forbs and shrubs at proportions similar to other bighorn sheep populations across the west, while the Antelope Island herd used forbs at higher levels than any other local herd. Additionally, the herd on Antelope Island was analyzed to compare differential use by rams and ewes. Our results indicate that there was no significant difference in diet between sexes on Antelope Island. Bluebunch wheatgrass (Pseudoroegneria spicata) was a common species across all sites and was an important forage for all populations. Managers may consider these proportions when seeding in bighorn habitat improvement projects.

No description available.

No description available.

The effect of seasonal cattle grazing on a newly reintroduced vii population of California bighorn sheep (Ovis canadensis californiana) in Big Cottonwood Canyon, Idaho, was studied. The hypothesis that bighorn sheep avoid cattle was tested. The issue of avoidance between bighorn sheep and livestock is arguable. Some studies have found that bighorn sheep avoid cattle while others have found no response of bighorn sheep to cattle. Evidence was found to document the avoidance of cattle by bighorn sheep. The size of the bighorn's home range and core area decreased with the movement of cattle into areas of high bighorn use. As cattle were moved into bighorn core areas, sheep responded by relocating. Bighorn sheep decreased their distance to escape terrain as cattle moved closer. The level and location of human disturbance on the study area did not have any effect on bighorn sheep movements or how sheep used the habitat. The severity of response observed is in marked contrast with the response of established bighorn populations to cattle. I suggest that newly reintroduced bighorn sheep are extremely sensitive to disturbance as a result of relocation trauma. Sensitivity may diminish over time.