We explore the application of the bootstrap unit root test to time series with heavy-tailed errors. The size and power of the tests are estimated for two different autoregressive models (AR(1)) using computer simulated data. Real-data examples are also presented. Two different bootstrap methods and the subsampling approach are compared. Conclusions on the optimal bootstrap parameters, the range of applicability, and the performance of the tests are made.

Climate change can alter the ecology of natural systems through various mechanisms, such as direct thermal effects on a consumer. However, consumers may employ behavioral mechanisms in response to warming. Among these may be spatial or temporal shifts in activity, making use of thermal heterogeneity on the landscape. Despite this, few studies consider the role of behavioral plasticity and spatial or temporal heterogeneity in the context of climate change. I conducted experiments to evaluate the importance of behavior in mediating the net effects of warming at the population and the individual level using captive white-tailed deer (Odocoileus virginianus). I created thermal heterogeneity over feeding stations using opaque and translucent roofing material. Feeding activity and consumption were monitored at these feeders. Activity patterns revealed deer disproportionally used the shaded feeder during the daytime and the unshaded feeder during crepuscular periods. I found that deer consumed less feed in group and individual experiments when feeders were unshaded. My results suggest that deer can use heterogeneity in the environment that may mediate the net effects of climate change. Furthermore, maintaining thermal heterogeneity may mitigate the direct effects of climate change on the consumer, but may lead to indirect effects at the community level.

Population genetics of white-tailed deer (Odocoileus virginianus) have been influenced through human actions including the translocation of deer from across the United States in the 1900s and, recently, the creation of the captive-cervid industry, which uses animal husbandry to manipulate genetic variation. To assess the effects of these actions, I studied the genetic variation of free-range and captive populations of deer across the southcentral U.S. using a 14 microsatellite panel. In free-range populations I found genetic structure that divided deer west to east along the Mississippi River. Additionally, I found that captive populations were genetically distinct from geographically proximate free-range populations. However, after 2 generations of hybridization, this distinction disappeared. Finally, using both Bayesian clustering and multivariate approaches, I was able to identify a non-native individual from local free-range populations in southern Mississippi. Using these methods, wildlife managers can further investigate cases of hybridization between non-native deer and free-range populations.

Factors associated with rank position are poorly understood whereas even fewer studies assessed if benefits were associated with increased rank position when resources were unlimited. I assessed whether age, body mass, size, and testosterone levels were important in rank establishment among 132 captive female white-tailed deer (Odocoileus virginianus). I also assessed if the benefit metrics of improved body condition, decreased stress level, and earlier parturition date were related to rank position. Deer in each of 9 study pens had a linear hierarchy with a mean h Πof 0.39 (SD = 0.09). Rank position was moderately related to age (P < 0.1) and was strongly related to body mass and size (P < 0.01). There was no relationship between benefit metrics and rank position (P < 0.1). Although increased body mass, size, and age improved rank position there were no benefits associated with increased rank when resources were unlimited.

No description available.

Migratory animals face numerous challenges that are often exacerbated by climate change. In the Arctic, where climate change is occurring at 4x the average global rate, species must adapt rapidly to novel conditions. I studied four species of sea ducks (Long-tailed Ducks Clangula hyemalis and Steller’s Polysticta stelleri, Spectacled Somateria fischeri, and King Eiders S. spectabilis), of which Steller’s and Spectacled Eiders are federally Threatened, and all are well below historic population sizes. I conducted three studies to assess how female sea ducks interact with their habitats between arrival on the breeding grounds and nesting. First, I assessed patterns of occurrence within diverse tundra wetland types by female sea ducks, in relation to three metrics of wetland resource availability: wetland surface area and biomass in benthic cores and emergent sweeps separately. I also monitored activity budgets of female sea ducks. Wetlands containing the emergent grass Arctophila fulva were highly selected for by all species relative to the wetland surface area and biomasses of prey, while large lakes, streams, and wetlands lacking Arctophila were avoided. Most time was allocated towards foraging or loafing, emphasizing the importance of energy acquisition during this transitional time period following migration and prior to nesting. Wetlands selected for broadly across species are under threat as climate change reduces the prevalence of these wetland types on the landscape, requiring adaptation to such novel conditions. My second study assessed how sea ducks rely upon prey resources within tundra wetlands, and upon stored tissues acquired in marine habitats. Female sea ducks must both produce eggs and sustain themselves throughout a ~30-day period from egg-laying through hatch, with potentially different nutrient sources for each aspect of the reproductive process. I sampled stable isotopes of proteins in egg membranes (reproductive endpoint) and in red blood cells (body maintenance endpoint), which I modeled relative to stable isotopes in a suite of prey taxa from freshwater tundra ponds and marine habitats. Across all four species, most proteins came from tundra wetlands (≥ 89% of modeled protein sources) for egg production. Smaller-bodied long-tailed Ducks and Steller’s Eiders relied heavily on the local environment for body maintenance and survival (red blood cells) during incubation, but larger Spectacled and King Eiders only gained ~60% of proteins locally, relying on the remaining 40% from body tissues acquired previously from marine habitats. Local wetlands provided 60-99% of proteins for female sea ducks. Freshwater habitats in which sea ducks forage warrant protection, and conservation for some species requires interagency cooperation across tundra, freshwater wetlands, and marine habitats. My third study assessed patterns of nest site selection across species, years, and spatial scales. How females choose nest sites has major implications for population processes. Decisions integrate information across spatial scales for each component of habitat a hen considers. I used boosted regression trees (a machine learning technique) to model suitability of nesting habitat for 414 variables of habitat features at six spatial scales. Social association with other ducks were highly important in determining suitability. Suitable habitat varied spatiotemporally among species, but the relative amount of suitable habitat was consistent across years for each species. Conservation for suitable habitat must include broad areas to incorporate interannual variability. Through these three studies, I assessed the relative use of; importance of; and reliance upon various wetland types, the relative importance of marine versus freshwater nutrients for reproduction, and the factors driving nest site selection in a guild of sea ducks facing imminent climate change.

Declining oak (Quercus spp.) dominance across the eastern U.S. is often attributed to fire exclusion and abundant white-tailed deer (Odocoileus virginianus). Fire restoration can negatively affect acorn germination and survival directly but also indirectly through impacts on seed predation. Similarly, masting events could influence oak regeneration success by altering deer behavior. To date, virtually no information exists assessing indirect effects of acorn consumers on oak regeneration. I developed two experiments to address this knowledge gap. In the first experiment, I determined if burning acorns affects predator removal rates. In the second experiment, I assessed the indirect effects of mast seeding on plant communities mediated by deer. Burning acorns decreased acorn removal rates. This could increase survival to spring for acorns that survived exposure to fire. Mast seeding increased local deer use, decreased the competitive advantage of local oak seedlings, but increased beta diversity in the understory.

The reproductive timing and success of white-tailed deer are important to managers. I evaluated the reproductive variability of pen-raised deer and wild populations within Mississippi and investigated effects of age, body condition and moon phase on conception dates. I also examined the reproductive potential of doe fawns from 3 regions of Mississippi. Individual conception dates varied more than expected and were not related to moon phase. Age affected individual conception date, although the effect may have been confounded by estimated gestation length. Population level variation was less than reported and could not be explained by moon phase or late-winter body condition. One of 65 doe fawns bred. The critical mass for reproduction may be lower in Mississippi than previous reports for the northern U.S. Regional variation in fawn breeding based on yearling lactation rates warrants additional research.

Previous research documented that white-tailed deer body mass and antler size varied across physiographic regions of Mississippi. Deer from regions with greater soil fertility had greater body mass and antler size; however, this information is known only for individuals 6 months of age and older. I monitored birth mass and skeletal size of fawns produced by bred, adult, female white-tailed deer transplanted from the Delta, Thin Loess (Loess), and Lower Coastal Plain (LCP) soil regions to fawn in the Mississippi State University Rusty Dawkins Memorial Deer Unit. I evaluated the effect of soil region of origin, litter size, and fawn gender on mass and size of fawns at birth. Birth mass was not as variable as mass of older animals, but LCP fawns were lighter and shorter than loess and/or delta fawns. Twins were lighter and shorter than singletons. Males were heavier than females. Differences between regional birth dates within the pens and estimated regional birth dates based on a fetal growth curve raises questions about the wide-spread application of this method of estimating deer breeding and fawning dates.

No description available.