Muskoxen (<i>Ovibos moschatus</i>) are relatively large herbivores living in an arctic environment where forage is sparse and its availability during long winters is often much reduced by snow and ice. Muskoxen cope by obtaining energy and nutrients from the low-quality sedges and grasses they eat, and from body reserves accumulated in summer and autumn. The objectives of this study were to evaluate the physiological and energetic adaptation of muskoxen to digestion of graminoid forage, and to measure the extent and reproductive significance of seasonal changes in body composition of female muskoxen. The first objective was addressed using two studies with captive muskoxen in Saskatoon, and the second during a field study on Victoria Island, Northwest Territories. In the first study, changes in body weight, intake, retention time and digestibility of a supplemented brome-alfalfa hay were measured in mature muskoxen during two seasonal cycles. Mean daily dry matter intake of breeding females was highest in July and August (62 ± 3.6 g/kg^0.75) then declined slowly to its lowest point in March and April (41 ± 0.7 g/kg^0.75). Mean retention time of hay, calculated from a chromium marker, declined (P<0.01) from 114 ± 4 h in March to 95 ± 4 h in July. Apparent organic matter digestibility decreased (P<0.01) from 74.7 ± 0.8% in winter to 61.7 ± 1.3% in summer. Compared with other ruminants, muskoxen are grazers exceptionally well-suited to slow, thorough digestion of graminoid forage. In the second study, the voluntary intake and apparent digestibility of a low-protein grass hay, similar in composition to diets of wild muskoxen in winter, were measured in five mature muskoxen and three mature Hereford cows during late winter 1993. Both species maintained body weight on the experimental diet but daily dry matter intake of the muskoxen was only 1/3 that of the cattle (32 ± 2 vs. 96 ± 3 g/kg^0.75; P<0.001). Apparent digestibility of organic matter, measured using chromic oxide, was higher in the muskoxen than in the cattle (58 ± 2 [SE] vs. 50 ± 3%; P=0.03). Muskoxen are particularly well adapted to digesting low quality graminoid forage at exceptionally low rates of intake. In the third study, the anatomical and chemical body composition of 22 muskoxen that varied widely in size, age and condition were analysed, and measures of body weight and condition were evaluated as predictors of body composition. The leanest muskoxen were four 5 to 15-day-old calves with 3.5 ± 0.5% (mean ± SE) fat in the IFBW, and the fattest were three females with 24.8 ± 1.4% fat. Muscle weight was best predicted from weights of individual muscles, protein weight from IFBW, bone weight from the weights of individual limb bones, and ash weight from IFBW. Combining kidney fat weight and a measure of body weight with up to three other measurements allowed dissectible and total fat weights to be estimated accurately. The extent of fattening in muskoxen exceeded that found in other wild ruminants with the exception of Svalbard reindeer (<i>Rangifer tarandus platyrhynchus</i>). In the fourth study, the body weight, body composition and reproductive status of 202 muskox cows from Victoria Island were analysed during 16 seasonal collections from 1989 to 1993. Adult muskox cows were lightest and leanest in May, when the ingesta-free body weight (IFBW) of newly-lactating adult cows was 116 ± 2 kg (adjusted mean ± SE) and a similar 112 ± 3 kg in nonlactating cows. Thereafter, the IFBW of lactating cows was virtually unchanged until July, increased rapidly during August, peaked in September at 166 ± 4 kg, then decreased to 148 ± 2 kg in November. In contrast, the IFBW of nonlactating cows increased throughout summer, reached a higher peak in September (176 ± 7 kg; P < 0.01) and changed little by November (164 + 2.1 kg). Pregnancy rates in this population increased from 0 in females 1.5 years old in the autumn to 25% in 2.5 year-olds and 62.5% in cows at least 3.5 years old. Lactation did not appear to peak until at least two months after calving, and was sometimes extended to more than a year. Lactation in November did not preclude pregnancy, but pregnant females at this time were fatter and heavier than nonpregnant cows. These results indicate substantial flexibility in reproductive patterns of muskoxen and an unique ability to maintain condition through long arctic winters. Based on these studies, the persistence of muskoxen through arctic winters can be ascribed in large part to exceptionally low maintenance requirements, along with an ability to thoroughly digest low-quality graminoid forage. Female muskoxen also deposit large quantities of fat in late summer and are able to conserve a large portion of them through early and mid- winter, and use them to support late-winter lactation. Muskox reproductive rates are strongly sensitive to nutritional influences. This suite of K-selected characters in muskoxen is consistent with a slow metabolism and a low rate of population growth.

Over the past 40 years, severe population fluctuations in Peary caribou (Rangifer tarandus pearyi) and muskoxen (Ovibos moschatus) living in the High Arctic of Nunavut has caused widespread concern. In order to better understand these fluctuations, patterns of population characteristics need to be examined. The best source for long-range information is from Inuit, who have interacted with these species on a regular basis over the long-term. This thesis presents the collection and documentation of observations by Inuit to describe the population distribution of caribou and muskoxen. Interviewees also shared their understanding of factors contributing to changes in abundance, and information concerning the ecology of these species. Interviewees from Resolute Bay have observed severe fluctuations in the abundance of caribou on Somerset, Prince of Wales, Russell, Cornwallis and Bathurst Islands and northern Boothia Peninsula. Interviewees from Grise Fiord indicated that changes in caribou populations on Devon and southern Ellesmere Islands have occurred but have not been substantial. Interviewees also indicated that the populations of muskoxen on Somerset, Prince of Wales, Devon and Southern Ellesmere Islands have increased, whereas muskoxen populations on Cornwallis and Bathurst Islands have been consistently low. Overall, interviewees expressed that changes in caribou and muskoxen populations are normal. However, interviewees continue to be concerned with the possibility of negative impacts caused by significant human disturbance (e.g., petroleum exploration). They also suggest that factors such as weather, presence of forage and the handling of animals influence the distribution, abundance and health of caribou and muskoxen. Interviewees also described the variability in the physical traits of Peary caribou throughout the High Arctic islands. Generally, from Boothia Peninsula to Bathurst Island the bones of caribou become smaller and their fur has a finer texture. On the islands north of Bathurst Island the features that are unique to Peary caribou become more pronounced. Interviewees also explained that overall, caribou are not negatively impacted by wolves and that a large abundance of muskoxen is often followed by the decline in the population of caribou in a specific area. The documentation of this information contributes to our understanding of two unique northern species, and has the potential to aid in shaping the management of human activities that may affect them. / Thesis (Master, Geography) -- Queen's University, 2012-10-12 14:51:42.667

Big Bone Lick (BBL) is a late Pleistocene and Holocene fossil locality in the Ohio River valley of Kentucky. This study utilized stable isotopes (δ13C, δ18O, and 87Sr/86Sr) in tooth enamel to reconstruct mobility and diet in Bison, as well as diet in Bootherium bombifrons. Isotopic results from seven Bison and two B. bombifrons are reported. Results suggest Pleistocene Bison and Bootherium occupied different dietary niches. Although both had C3-dominated diets, Bison occupied more open environments than B. bombifrons. Two bison from the late Holocene deposit had diets that consisted of more C3 vegetation than Pleistocene bison, which may indicate these individuals occupied a closed C3 landscape. However, one specimen previously identified as late Holocene had diet and mobility patterns consistent with Pleistocene bison, which could indicate temporal mixing. Pleistocene and Holocene Bison have 87Sr/86Sr values that suggest they spent most of their time in places other than BBL.