Stable isotopes of mammoths and mastodons have the potential to illuminate ecological changes in late Pleistocene landscapes and megafaunal populations as these species approached extinction. The ecological factors at play in this extinction remain unresolved, but isotopes of bone collagen (δ13C, δ15N) and tooth enamel (δ13C, δ18O, 87Sr/86Sr) from midwestern North America are leveraged to examine ecological and behavioral changes that occurred during the last interglacial-glacial cycle. Both species had significant C3 contributions to their diets and experienced increasing levels of niche overlap as they approached extinction. A subset of mastodons after the last glacial maximum exhibit low δ15N values that may represent expansion into a novel ecological niche, perhaps densely occupied by other herbivores. Stable isotopes from serial and microsampled enamel show increasing seasonality and decreasing temperatures as mammoths transitioned from Marine Isotope Stage (MIS) 5e to glacial conditions (MIS 4, MIS 3, MIS 2). Isotopic variability in enamel suggests mobility patterns and life histories have potentially large impacts on the interpretation of their stable isotope ecology. This study further refines the ecology of midwestern mammoths and mastodons demonstrating increasing seasonality and niche overlap as they responded to landscape changes in the final millennia before extinction.

Feeding ecology and trophic interactions of six species of wading birds were explored through a combined analysis of stable isotope profiles and endoparasite communities. Stable isotopes broadly characterize the feeding preferences and geographic information, while parasite communities reflect long-term trends in feeding ecology. Deceased birds were obtained from four South Florida wildlife rehabilitation organizations. Of the 81 birds dissected, 73 contained parasites. Parasites were predominately found within the gastrointestinal tract. Host and range extensions were noted for several parasite taxa. Bird host species had a significant effect on the parasite community (P=0.001) while wildlife center location and maturity status did not. Stable nitrogen (δ15N) values for pectoral muscle tissues, representing approximately 24 days, ranged from 6.44 to 13.48‰ while stable carbon (δ13C) values ranged from -33.39 to -11.66‰. δ13C varied significantly among location (P=0.0002) and δ15N varied significantly among species (P15N and δ13C was analyzed in combination; bird species (P=0.001) and location (P=0.001) were significantly different. By using this combined approach of stable isotope analysis and parasite identification, it was possible to elucidate more components of bird feeding ecology. Stable isotope analysis provided knowledge on trophic interactions based on δ15N values, while δ13C was used to determine the differences in geographic foraging location. As endoparasites are acquired trophically via food-web interactions, identifying the parasite community allowed for trophic links to be drawn between organisms present within the same environment. Combining these two techniques allows for an abundance of information on feeding ecology and trophic interactions to be obtained.

Indiana University-Purdue University Indianapolis (IUPUI) / Drylands cover 40% of the earth’s terrestrial surface supporting over 2 billion people, the majority of whom reside in developing nations characterised by high population growth rates. This imposes pressure on the already limited water resources and in some dryland regions such as southern Africa, the origins and dynamics of rainfall are not well understood. Research has also tended to focus on factors limiting (e.g., rainfall) than sustaining productivity in drylands. However, non-rainfall water (NRW) e.g., fog and dew can supplement and/or exceed rainfall in these environments and could potentially be exploited as potable water resources. Much remains unknown in terms of NRW formation mechanisms, origins, evolution, potability and potential impact of global climate change on these NRW dependent ecosystems. Using Namibia as a proxy for drylands and developing nations, this dissertation applies stable isotopes of water (δ2H, δ18O, δ17O and d-excess), cokriging and trajectory analysis methods to understand ecohydrological processes. Results suggest that locally generated NRW may be a regular occurrence even in coastal areas such as the Namib Desert, and that what may appear as a single fog event may consist of different fog types co-occurring. These results are important because NRW responses to global climate change is dependent on the source, groundwater vs. ocean, and being able to distinguish the two will allow for more accurate modelling. I also demonstrate, that fog and dew formation are controlled by different fractionation processes, paving the way for plant water use strategy studies and modelling responses to global climate change. The study also suggests that current NRW harvesting technologies could be improved and that the potability of this water could raise some public health concerns related to trace metal and biological contamination. At the same time, the dissertation concludes that global precipitation isoscapes do not capture local isotope variations in Namibia, suggesting caution when applied to drylands and developing nations. Finally, the dissertation also reports for the first time, δ17O precipitation results for Namibia, novel isotope methods to differentiate synoptic from local droughts and suggests non-negligible moisture contributions from the Atlantic Ocean due to a possible sub-tropical Atlantic Ocean dipole.

No description available.

The brown bear (Ursus arctos) is a generalist omnivore that occupies diverse habitats and displays high levels of behavioral plasticity. Plasticity in foraging behavior can result in variable diets across a population, and allow individuals to use a greater variety of resources. The distribution of food in space and time may also be an important factor in determining brown bear resource selection as it can greatly influence foraging efficiency. Our objectives were to determine if seasonal brown bear home ranges were influenced by temporal availability and spatial distribution of resources and if deviation from an optimal diet influenced brown bear body condition. Understanding how the spatial and temporal distribution of food influences brown bear space use and the relationships between behavioral plasticity and the ability of populations to persist in dynamic environments could provide additional insights into the eco-evolutionary advantages of variable foraging behavior and ultimately population resilience.

Managed loblolly pine (Pinus taeda) stands are common in the southeastern United States and provide young forest conditions for early successional breeding birds. Common pine management practices (e.g. hardwood control) and novel practices (e.g. switchgrass [Panicum virgatum] intercropping), may influence breeding bird use. I evaluated breeding bird abundance, diversity, and resource use within loblolly stands treated to control hardwood species, intercropped with switchgrass, and with no additional management. Hardwood control and switchgrass intercropping both decreased hardwoods and shrubs, and increased forbs. Switchgrass intercropping increased some early successional bird abundances. However, diversity was not different among treatments. Switchgrass intercropping increased 13C:12C in birds and vegetation; both hardwood control and switchgrass intercropping increased 15N:14N in birds and vegetation. Birds moved freely among stands of different ages and management practices. My results suggest these practices improve conditions for some early successional birds and may help maintain ecological value of loblolly stands for birds.

The wild turkey is endemic to North America and has played a role in human cultures past and present. However, with the turkey's elusive behavior some aspects of its ecology are challenging to understand. Diet is one of these difficult aspects to study. The purpose of this study was to determine the diet selection of wild turkeys in central Utah using non invasive stable isotope technology. We hypothesize that turkey diet is highly specific, that consumption of specific plant species correlates with the needs of the individual turkey, and that stable isotope analysis will reveal patterns in annual dietary intake. Vegetative forage, turkey feces, and feather samples were collected from the Salt Creek area east of Mt. Nebo during 2007 and 2008. Feces samples were identified to bird sex and forage samples were identified to family or growth form (grass, forb, and shrub) when species could not be determined. Carbon isotope analysis of turkey feces and dietary forage using a mass spectrometer revealed that composition of turkey diet changed seasonally and yearly. Isotope analysis of dietary forage according to vegetative growth form revealed that turkey diet for the spring of 2007 contained approximately 46.0% grasses, 30.0% forbs, and 24.0% shrubs and trees. The summer diet for 2007 consisted of 39.0% grasses, 31.0% forbs, and 30.0% shrubs and trees. During spring 2008, grasses comprised 10.3% of the diet whereas forbs and tree/shrubs constituted 53.0% and 36.7%, respectively. Turkey summer diet for 2008 was found to consist of 13.1% grasses, 48.5% forbs, and 38.4% shrubs/trees. Isotope analysis of turkey feathers revealed no significant patterns in isotope signatures in relation to vegetation type and season of year. Stable isotope signatures resulting from fecal analysis reflect opportunistic foraging behavior as birds utilized a wide variety of forages throughout the year. Our findings suggest habitat structure and type play a more major role in wild turkey survival then food type. These findings also strengthen the need to rigorously evaluate turkey habitat prior to reintroduction with respect to vegetative composition and structure and their relationship with wild turkey behavior and life processes.

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.

The Baltic region was a vibrant center of power and economic prosperity in medieval Europe; Lithuania in particular. Until now, little stable isotopic analysis has been utilized to assess diet in this region during this time period. The aim of this study was to undertake a preliminary assessment of the composition of diet at late medieval Alytus (late 14th to early 18th centuries) from bone (N=35) and dentin (N=38) collagen samples. The stable carbon isotopic data suggest a diet primarily comprised of C3 plants such as barley, rye, wheat, and flax, and animals consuming C3 plants. The stable nitrogen isotopic data indicate the use of aquatic resources, and reflects the protein portion of the diet as including mainly terrestrial non-legumes. There are no significant differences in the pattern of resource consumption between juvenile males and females. There is a significant difference between adult males and adult females; the more depleted bone collagen ?15N values indicates that adult females were consuming less protein resources, or protein resources of a lower trophic level, compared to their male counterparts. This difference could also be affected by physiological factors such as pregnancy or disease. A difference between juvenile and adult stable nitrogen isotope values might indicate latter weaning of juvenile males, the incorporation of more terrestrial or aquatic protein into juvenile male diet, the incorporation of less terrestrial or aquatic protein into adult female diet, or a combination of the three.

The North Pacific humpback whale (Megaptera novaeangliae) is a wide-ranging baleen whale species with a complex life history and population structure. As seasonal migrants, humpback whales are known to inhabit cooler, high-latitude waters when foraging and low-latitudes for mating and calving. Beyond this general migratory pattern, a number of demographic characteristics including, abundance, distribution, seasonal occurrence, and prey preferences remain unknown or poorly described. A complete understanding of humpback whale ecology is therefore lacking. Many methods used to explore these aspects of cetacean ecology are either prohibitively expensive or limited in the scope of what can be learned from their use. Fortunately, in recent years, the analysis of stable isotope ratios of animal tissues has proved a valuable and relatively inexpensive technique for providing information on trophic position, diet, and feeding origins of migratory populations. This study employed techniques in stable isotope ecology to increase knowledge of the population structure, migration routes, and foraging ecology of North Pacific humpback whales. Skin samples were collected from free-ranging humpback whales throughout all known feeding and breeding grounds and were analyzed for stable carbon ([delta]13C) and nitrogen ([delta]15N) isotope ratios. The population structure of humpback whales was first explored through geographic differences in stable isotope ratios. Stable isotope ratios varied significantly with location of sample collection. Based on this analysis, foraging animals were separated into six feeding groups. Classification tree analysis was then used to determine which isotopic variables could be used to predict group membership. Probable migratory linkages were then described by applying results of classification trees to [delta]13C and [delta]15N of animals sampled on breeding grounds. Strong migratory connections between the eastern-most foraging and breeding areas and the western-most areas were reflected in similarities of stable isotope ratios. Foraging ecology was then examined through calculation and comparison of the relative trophic levels of the six feeding groups. Isotopic values suggest some feeding groups are piscivorous, while others feed on a more mixed diet. These results can be used to determine if differences in diet composition between groups result in differences in accrued nutritional benefits, negatively impacting reproductive success and survival relative to fish eating groups. Finally, to gain insight into specific foraging habits, the diet of one group of humpback whales was modeled using an isotope mixing model. The [delta]13C and [delta]15N of Kodiak Island, Alaska humpback whales and several species of potential prey indicate that these animals likely rely heavily on euphausiids (Thysanoessa spinifera), Pacific sandlance (Ammodytes hexapterus), and capelin (Mallotus villosus). This study represents the first application of stable isotope ecology to an entire population of marine mammals. Stable isotope analysis was successfully applied to describe and improve understanding of the demographics of North Pacific humpback whales.