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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Agricultural subsidies affect isotopic niche size in elk and white-tailed deer

Coulson, Andrew 07 January 2015 (has links)
Agricultural crops are a food subsidy for wild ungulates that can bring animals into close proximity, facilitating disease spread. We used stable isotope analysis to reconstruct the diets of elk and white-tailed deer in three areas in the Canadian prairies and calculated their isotopic niche breadth. Isotopic niche breadth was greater for deer than elk, indicating that deer are a generalist species composed of individual specialists with varied diets, while elk are individual generalists. White-tailed deer niche breadth decreased with increasing consumption of agricultural foods in early fall, but not on an annual timescale. Elk niche breadth did not change with consumption of agricultural foods. Agricultural sources were 40-80% of the diets of both species in all areas. Agricultural feeding may increase the risk of disease in elk and deer not only by increasing their apparent density at feeding sites, but also by subsidizing increases to their overall density.
2

THE ROLE OF SOCIALITY AND DISTURBANCE IN SHAPING ELK (CERVUS CANADENSIS) POPULATION STRUCTURE

Slabach, Brittany L. 01 January 2018 (has links)
Investigating how and why individuals interact is an important component to understanding species ecology. The type and patterning of relationships (social structure) provides pertinent insight into how ecological factors such as spatial heterogeneity of resources and predation influence associations between individuals. Many taxa exhibit temporally fluid association patterns, where individuals associate with a variety of others at different rates. Ungulate species exhibit prime examples of highly fluid grouping patterns and individuals form both temporary and long-term associations. The effects of human disturbance on ungulate behavior are well documented and these changes are further exacerbated during the hunting season. Species such as elk (Cervus canadensis) are highly managed having subsistence, recreational, and economic value. The demographic effects of selective take or harvest regimes on population dynamics are known, but how human disturbance, including hunting, influences ungulate social structure on a fine-scale has not been explored. I aimed to investigate the relationship between human disturbance and social structure in a population of elk residing in southeastern, Kentucky, USA. I choose to focus on female elk given the importance of adult female survival to population dynamics and previous knowledge of some social affinity between females. I begin by discussing factors that influence ungulate sociality, how human disturbance can influence sociality and how a better understanding of association patterns could aid in management decisions. I then present two distinct yet vital studies to understanding this relationship: (1) investigation of survival of elk in Kentucky and (2) investigation of association patterns in a human dominated landscape. Hunter harvest is the primary cause of elk mortality in both eastern and western populations in North America and 85.2% of all elk mortalities in Kentucky were hunter harvest related. Older (> 5) males and younger (< 2) females had significantly higher hazards of dying relative to other age classes. Moreover, the establishment of a limited entry hunting area to prevent local overharvest of males had no effect on male survival, but instead may have resulted in local overharvest of females at one site residing on publicly accessible land. Female elk exhibit both weak and strong association patterns. I found that relatedness was significantly greater within sites, similar to patterns found in other cervid species. Association patterns within sites were not explained by age class; and relatedness was only positively correlated at one site. The sites investigated differed in the type and frequency of human disturbance, specifically hunting, suggesting that the disparity in association patterns were driven by these differences. I conclude with two smaller studies, suggesting an indirect consequence of coal surface mining disturbance on ungulate foraging behavior and the potential for interstate transfer of ecto-parasites during reintroduction efforts. This research reinforces previous findings and further refines our understanding of ungulate social structure. Consideration of temporal variation in association patterns of ungulates and other species is important to quantify the effect of disturbance on population and social processes, but also to increase our understanding of dynamic structures. Quantifying the resiliency of structure to disturbance is a priority to further our understanding of the ecology and conservation of these species.
3

VITAL RATES AND HABITAT SELECTION OF BULL ELK (<em>CERVUS CANADENSIS NELSONI</em>) IN SOUTHEAST KENTUCKY

Hast, John Tyler 01 January 2019 (has links)
Globally, male ungulate species are heavily managed for their sporting and trophy qualities. North American elk (Cervus canadensis) are typically managed using a male-biased harvest regime, placing increased chances of mortality on males in these hunted populations. To manage for trophy quality animals that typically represent older age classes, wildlife managers have implemented many age-biased harvest regulations, including spike-only tags and antler point restrictions. Many of these age-biased harvest regulations have fallen short of their desired goal of producing older bull elk. Consequently, the consensus has evolved to center on an overall reduction in harvest pressure. The state of Kentucky began an elk restoration project in 1997, with 1,553 elk released through 2002. As with other modern elk restoration projects, the male demographic received little research attention in the years immediately post restoration. The difficult logistics surrounding the transport of adult male elk and the reluctance of source states to part with potential trophy animals, led to few adult male elk receiving tracking collars to monitor this demographic. Hunter success rates indicated a growing male component to this population in light of the lack of a radio-marked cohort. With overall population numbers increasing in step with predictive models, so too did hunting tag numbers and hunting pressure. This rise in hunting pressure likely forced elk to become more cryptic, giving rise to the perception of a decline in the elk population, especially older age class male elk. This research represents the first in-depth look at the survival rates and habitat selection of adult male elk in Kentucky. Recent improvements in field methodology have allowed for the more efficient acquisition of a robust sample of adult male elk. I conducted a radio-telemetry study of adult male elk within southeast Kentucky to investigate the following: (1) survival and cause-specific mortality factors, (2) survival during the fall hunting period, (3) changes in survival following the implementation of a limited entry area (LEA) enclosing our study area, and (4) the associations of morphometric characteristics with the survival of adult male elk. Given the lack of information on the habitat use of male elk, a cohort of global positioning system (GPS) equipped elk were captured to investigate: (1) seasonal habitat use of male elk, (2) quantification of availability of male elk in readily viewable habitats, (3) changes to the percent of open land within the fall home range of adult male elk, and (4) the influence of open land on survival rates. To investigate the dispersal of male elk, I compared genetic relatedness to space use. Finally, in an attempt to better understand our existing capture methodologies, I analyzed drug induction and reversal metrics for the immobilization drug Carfentanil citrate. Survival analysis resulted in a 16.9% (CI = 12.2 – 23.7) three-year survival rate for adult male elk. An improvement in survival rate (p = 0.077) was noted after the implementation of an LEA system that limited the number of hunters in the study area. No morphometric characteristics were observed to have an association with survival, indicating that hunters indiscriminately harvest male elk. Predictive, habitat use models for male elk indicated a preference for grass habitats and use of habitats near grass patches. Seasonal variation in habitat use was observed with the greatest daily use of grass habitats occurring in the winter season. Adult male elk selected for open land at greater rates than is available across the study area. Over the course of three hunting seasons, elk were found to reduce their use of open land during daylight hours, and we anecdotally believe this to be a response to hunting pressure. A reduction in survival probability of male elk was directly related to use of open land in the final year of the project. Little home range overlap was observed between related male elk, indicating some level of dispersal and intra-specific competition. Predictive models for Carfentanil immobilization indicated an increase in efficacy of a shoulder injection as opposed to a hindquarter drug injection. Future management of elk in Kentucky should center on promoting the persistence of healthy grassland areas within the elk restoration zone and meeting hunter expectations. Hunter expectations should be gathered and management tailored to meet their desires and the objectives of the management agency. This research indicates that hunters harvest male elk regardless of trophy characteristics, yet we are not sure of the underlying reasons. The interaction of habitat and survival is complex and further complicated by the reclaimed coal mines that Kentucky elk live upon. Habitat management priorities should focus on a heterogeneous, yet healthy habitat that meets the needs of all species residing on these once-exploited lands.
4

Disease Ecology and Adaptive Management of Brucellosis in Greater Yellowstone Elk

Cotterill, Gavin G. 01 May 2020 (has links)
Brucellosis is a bacterial infection that primarily affects livestock and can also be transmitted to humans. In the Greater Yellowstone Ecosystem (GYE), elk (Cervus canadensis) and bison (Bison bison) are habitual carriers of Brucella abortus, which arrived to the region with cattle over a century ago. The disease was eliminated from cattle in the United States through widespread control efforts, but is now periodically transmitted back to cattle on open rangelands where they can come into contact with fetal tissues and fluids from disease-induced abortions that occur among elk during the late winter and spring. In Wyoming, south of Yellowstone National Park, there are 23 supplemental feedgrounds that operate annually and feed the majority of the region’s elk during a portion of the winter. The feedgrounds are controversial because of their association with brucellosis and may be shuttered in the future in part due to the arrival of chronic wasting disease. Using data collected at these feedgrounds, this study investigates the role of winter feedgrounds in the ecology of this host-pathogen relationship: it evaluates the full reproductive costs of the disease to affected elk, how herd demography influences pathogen transmission, and assesses management strategies aimed at reducing pathogen spread among elk. Using blood tests for pregnancy status and brucellosis exposure in female elk, I demonstrated a previously undocumented fertility cost associated with the pathogen which is not due to abortions, but which nearly doubles the estimated fertility cost to affected individuals. I also built mechanistic transmission models using time-series disease and count data from feedgrounds. Within that framework, I assessed various management actions including test-and-slaughter of test-positive elk, which I found to be counterproductive due to rapid recovery times and the protective effects of herd immunity. The overall picture that emerges of winter feedgrounds is one of imperfect practicality driven by social and political consideration, not pathogen control. These results illustrate the underappreciated importance that recruitment and population turnover have on the transmission dynamics of brucellosis in elk, a pathogen which itself flourishes in the reproductive tracts of individual animals and thus impacts vital rates at the population level. Together, this study contributes to the field of disease ecology using a unique long term disease data set of free-ranging wild ungulates.
5

Improving Capture Methods for Neonate Ungulates

Turnley, Matthew T. 15 March 2022 (has links)
The capture of neonate ungulates has played an integral role in studies of habitat selection, phenology, survival, and other topics of ecological interest. However, neonates can be difficult for researchers to locate and capture. Neonate ungulates are born in habitats with reduced visibility, frequently spend time in a concealed, prone position, and may display cryptic coloration. In an attempt to improve researchers' likelihood of locating and capturing neonate ungulates, multiple capture methods have been developed. Much remains unknown about biases associated with capture methods and how to further improve capture methods once biases are understood. Our objectives were to determine if opportunistic captures of neonate mule deer (Odocoileus hemionus) bias estimates of litter size (Chapter 1) and to determine when searches for neonate elk (Cervus canadensis) should begin following parturition to maximize likelihood of capture while minimizing disturbance (Chapter 2). To complete our objectives, we analyzed data from 161 litters of mule deer and 55 attempted captures of neonate elk during 2019-2021 in Utah, USA. Estimates of litter size derived from opportunistic captures of mule deer were smaller than estimates derived from movement-based captures or captures completed with the aid of vaginal implant transmitters (VITs). The time elapsed between parturition and when searches were initiated for neonate mule deer did not influence estimates of litter size, but we could only analyze this relationship for VIT-aided captures within approximately 2 days of parturition. Until more data are available, we recommend that estimates of litter size for neonate mule deer be completed using movement-based or VIT-aided captures within approximately 2 days of parturition. When attempting to capture neonate elk, reducing the time elapsed between parturition and when searches were initiated resulted in a decreased search length, decreased distance traveled by the neonate, and increased likelihood of capture. We initiated searches as early as 3.6 hours post-parturition with no evidence of maternal abandonment and probability of capture was near or above 90% when searches were initiated within 10 hours of parturition. We recommend that searches for neonate elk be initiated 3.6-10 hours post-parturition. Future researchers can use utilize our results to perform captures of neonate ungulates that minimize bias, decrease disturbance, increase efficiency, and maximize the likelihood of capture success.

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