Behaviour studies were undertaken on three populations of free living American sheep, one being a Stone's sheep (Ovis dalli stonei) one a Dall's sheep (0. d. dalli) and one a bighorn sheep population (0. canadensis canadensis). The habitat-, body care- and social behaviour patterns - except those of mother and young - were described in detail. Each social interaction recorded was transferred to a computer card. 3800 interactions were analysed and form the basis of the quantitative data reported. American sheep show only minor quantitative differences in their social behaviour. However, behavioural differences within populations of the same species occur and appear to reflect population quality. Sheep evolution is conceived as follows: Sheep evolved from rupicaprid ancestors. They evolved large horns, pneumated skulls, lost or reduced display hairs, increased the size of the rump patch and increased sexual dimorphism. The damaging fighting forms of the rupicaprids were replaced by a ritualised form of combat. Sheep lost the thick hide as a defence mechanism, and defend themselves by catching the horn blow with their horned head. Skulls evolved to absorb concussion. The broadside display was replaced by horn displays. Ram horns function not only as weapons, but also as guards, display organs and rank symbols. Sheep appear to have evolved rapidly whenever they colonized new habitat in the wake of retreating glaciers. The expanding populations would experience intense selection for forceful clashing and larger horn size. Large horn size is a function of neoteny in rams. Rams mature sexually at 1.5 - 2.5 years of age, but do not mature behaviourally or reach ultimate growth form until they are 7-8 years old. Females are paedo-genic forms which remain similar in appearance and behaviour to sexually mature yearling rams. Neoteny also explains the long body growth of rams, the reduction and loss of the neck ruff, increased sexual dimorphism, the intense gre-gariousness of females and of juvenile rams, the increasing independence and leadership of rams as they grow older, and the more frequent use of aggressive patterns by bighorn as compared to thin horn sheep. Rams prefer to interact with rams of their own horn size and with females. They treat subordinates, irrespective of sex, much the same as they treat females. Rams change their behaviour not with the sex of the companion but with its dominance rank. The more that subordinate rams resemble females in appearance, the more they are treated sexually by dominant rams. Subordinate rams may act like females to the extent of urinating, or, assuming lordosis when mounted. Non-estrous ewes withdraw from rams, but estrous ewes remain and act like subordinate rams. Ewes are guarded and defended singly as they come into heat. They are followed by a group of rams. The largest horned rams guard and mount estrous ewes. Rams fight throughout the years, not for females, but for dominance. Despite intense competition, the dominant ram takes the estrous ewe away from the subordinate uncontested. Sheep changed primarily in social adaptations, which evolved quite independently of habitat - or body care adaptation. / Science, Faculty of / Zoology, Department of / Graduate

This study compared the foraging behaviour and nutrition of Stone's sheep (Ovis dalli stonei) which had access to burned range to that of sheep on unburned range throughout the year. In winter, sheep were restricted to areas with less than 25-30 cm of snow. For most sheep this meant windswept, alpine ridges, but one small population used a burned, subalpine slope. Grazing pressure was high on these restricted winter ranges, particularly during a severe winter, resulting in removal j of all the forage from alpine range, and leaving only very poor quality forage on the subalpine range. The poor winter nutrition was reflected in low fecal nitrogen and DAPA levels and high Protostronqylus counts. In spring, sheep used either natural or fire-induced subalpine clearings to obtain early new plant growth. Forage quantity was much lower on unburned ranges, but biting rate and foraging time were the same as on burned ranges with high forage biomass. Quality of available forage and food intake were also similar. The foraging behaviour of Stone's sheep appeared to be similar to domestic sheep in that intake rate was primarily dependent on grass length rather than forage density. Sheep moved to higher elevations as the season progressed which provided them with access to the higher quality alpine forage. Regular use of mineral licks in summer apparently satisfied their sodium requirement. Grasses and sedges were the most important foods throughout the year although forbs and browse were important in the summer. Adult mortality rates were low. Lamb production was low following severe winters, presumably due to poor nutrition. An explanation for changes in lamb production based on density-dependent selective feeding was developed. Burned ranges were of limited value to Stone's sheep because they were usually unavailable as winter range, did not provide superior spring range and were not used in summer. Horn growth, however, appeared to be slightly better on burned ranges. A model of nutrient intake is developed to investigate the seasonal pattern of nutrition on burned and unburned ranges. / Forestry, Faculty of / Graduate

No description available.

Inaug.-diss.-Bern. / "Verzeichnis der benutzten literatur": p. [106]-108.

I examined habitat use by desert bighorn sheep (Ovis canadensis medicana) in the Little Harquahala Mountains, Arizona from 1989 to 1992. I compared microsites used by male, female, and mixed-sex groups. I also compared use of microsites by sheep to random sites during the breeding and nonbreeding seasons. There were no differences in use of microsites between the breeding and nonbreeding seasons. However, microsites used by sheep had steeper slopes, more barrel cactus (Ferocactus wislizenii), higher topographic position, and more foothills palo verde (Cercidium microphyllum) than random sites. I examined seasonal diets. There were no seasonal differences between the diets of males and females. Brittle bush (Encelia farinosa), desert ironwood (Olneya tesota), fairy duster (Calliandra eriophylla), foothills palo verde, janusia (Janusia gracilis), Mormon tea (Ephedra torreyana), ratany (Krameria parvifolia), wild buckwheat (Eriogonum fasciculatum), grama grass (Bouteloua spp.), bedstraw (Galium spp.), borage (Borage spp.), and barrel cacti were present in diets all seasons. Barrel cactus is a seasonally important part of the diet, providing moisture during hot, dry periods. Forage selection is not a factor in the sexual segregation of desert bighorn sheep in the Little Harquahala Mountains. I examined habitat use by female sheep relative to the timing of parturition from 1989 to 1991. I compared range size and microsite habitat components of female sheep prior to and following parturition to random sites. Nineteen lambs were born to 10 females and 6 lambs survived $\ge$6 months. Lambs that died lived an average of 34 days. Five females did not raise any lambs that lived $\ge$6 months in any year. No female raised a lamb that lived $\ge$6 months 2 years consecutively. Females reduced their range sizes as lambing approached. Individual females used the same lambing areas repeatedly. Microsites used by female sheep were steeper and more rugged than random sites. Microsites used by females for 8 weeks after parturition had significantly less barrel cactus than was found at random sites. The traditional use of parturition sites in rugged terrain may outweigh the increased need for water by lactating females.

I described recreational use in mountain sheep (Ovis canadensis mexicana) habitat in the Pusch Ridge Wilderness (PRW), Tucson, Arizona. I also examined human attitudes held by PRW recreationists and homeowners within 1 mile (1.6 km) of PRW boundary towards several mountain sheep management options. I used geographic information system modeling and social science survey methodology. Recreational use along two trails that traverse mountain sheep habitat was frequent (66 individuals/day use Pima Canyon trail, 26 individuals/day use Romero Canyon trail) and primarily limited to the lower 3 miles (4.8 km) of the trails. Compliance with existing dog leash regulations is low (41.8% on Pima Canyon trail, 62.8% on Romero Canyon trail). Recreationists and homeowners within 1 mile (1.6 km) of PRW support the elimination of dogs within PRW and support planned burns of PRW to improve mountain sheep habitat. Recreationists and homeowners also support closing all or parts of PRW to protect the long term viability (>100 years) of the sheep population. Homeowners within 1 mile (1.6 km) of PRW primarily enjoy passive recreational use of PRW (i.e, viewing the wilderness).

No description available.

Mountain sheep (Ovis canadensis mexicana) in the Pusch Ridge Wilderness (PRW), Santa Catalina Mountains, Arizona have abandoned historic habitat and now occupy 44 km². I used univariate analyses to quantify differences of physiographic and vegetational variables between abandoned habitat and habitat that is still used by mountain sheep. A discriminant function model characterized the magnitude of the differences between the 2 habitats. Habitat that supports mountain sheep has less human disturbance and is more open with more side oats grama (Bouteloua curtipendula), red brome (Bromus rubens), brittle bush (Encelia farinosa), and forb cover, but less ground cover, bush muhly (Muhlenbergia porteri), and turpentine bush (Haplopappus laricifolius) than habitat that was abandoned by mountain sheep. Fire is important in still used habitat because it reduces tall plants that obstruct mountain sheep vision. Human disturbances should be minimized in mountain sheep habitat.

No description available.

No description available.