<p> Rivers in semi-arid regions are highly sensitive and pressured yet can support diverse assemblages of species. In central New Mexico, the Rio Grande (River) is the lifeblood of the Middle Rio Grande Valley (MRGV), a semi-arid region which maintains large urban and agricultural centers and is also the principal wintering area for the Rocky Mountain Population of greater sandhill cranes (<i>Antigone canadensis tabida</i>). Human-induced environmental change has transformed the MRGV and habitat availability prompting concerns for the population. To address these concerns, I investigated dietary and behavioral responses of sandhill cranes to the collection of features that function as winter habitat. In Chapter 1, I demonstrated a novel application of stable isotopes to evaluate dietary reliance of sandhill cranes on corn subsidies provisioned by natural resource agencies, estimated rates of carbon isotope incorporation in tissues of sandhill cranes, and estimated tissue-derived winter arrival dates of sandhill cranes. I found subsidized corn was the primary dietary component of sandhill cranes, rates of carbon isotope incorporation in sandhill crane tissues differed predictably by metabolic activity, and estimated tissue-derived arrival dates on wintering grounds approximated actual arrival dates. In Chapter 2, I advanced a hierarchical Bayesian framework for overcoming challenges and improving analysis of behavioral data frequently generated in animal behavior studies and used behavioral observations of sandhill cranes as a case study. In Chapter 3, I estimated energetic and temporal availability of corn subsidies and seasonal energy requirements of sandhill cranes. I found seasonal energetic requirements of the population are likely satisfied by corn subsides but not without strategic planning. In Chapter 4, I examined how current landscape and riverine configuration influenced patterns of diel habitat selection by sandhill cranes. Sandhill cranes avoided sources of anthropogenic disturbance, relied heavily on managed public land resources, and selected roosting locations in the Rio Grande with a wider channel, interspersion of sandbars and shallow water, and low channel bank vegetation. My research suggests sandhill cranes have coped with alterations that have led to current conditions in the MRGV, however, habitat-related resources will need to be managed adaptively as drivers of environmental change will undoubtedly influence future circumstances. </p><p>

<p> Effective conservation strategies for imperiled species require an understanding of processes that influence fitness throughout the organism's life cycle and across the range of habitats needed to complete that cycle. I evaluated factors that affect population viability of bull trout <i>Salvelinus confluentus, </i> a threatened freshwater char species, throughout individual life stages and over the entire life cycle. </p><p> I assessed the relationship between bull trout egg incubation success and environmental variables. Egg survival was negatively related to the percent of fine sediment in redds and positively related to hydraulic conductivity and the strength of downwelling. Next, I quantified juvenile bull trout survival rates and described movement patterns for this life stage. Juvenile bull trout emigrated from natal headwaters into larger rivers throughout the entire year and across a range of sizes. Estimates of juvenile survival rates improved dramatically when emigration was incorporated into the analysis. </p><p> I integrated my observations of bull trout survival, growth, and movement to create a life-cycle model, which I used to better understand how populations respond to changes in specific demographic rates. Bull trout populations were particularly sensitive to changes in juvenile growth and survival. The relative effect of changes to fertility rates and adult survival varied depending upon whether a population was composed primarily of large, migratory, or smaller, resident individuals. Dispersal helped to lower the probability of extinction for small or declining populations when neighboring populations were stable. </p><p> My research demonstrates that bull trout require access to habitats throughout entire watersheds to maintain population viability. My results suggest that limiting anthropogenic sources of fine sediment and maintaining areas of channel complexity that promote downwelling can be important for bull trout embryo survival. Management decisions should also consider the diverse behavior of juvenile bull trout and the wide range of habitat they use. Additionally, connectivity between populations is likely to be important for declining populations to persist. The diversity of life-history strategies expressed by bull trout helps maintain demographic stability within and among populations. As such, preservation of habitat integrity and full life-history diversity is imperative for conservation and recovery of bull trout populations range-wide.</p>

<p> Increased agriculture and urbanization in southwestern Illinois have severely fragmented the forests of the region. Habitat fragmentation may cause lower species richness, population declines, or extirpation due to phenomena such as edge effects, inbreeding depression, and stochasticity. The effects of habitat fragmentation on suburban wildlife are poorly understood, especially for small mammals such as the Southern Flying Squirrel (<i>Glaucomys volans</i>). Flying squirrels are arboreal rodents whose presence in a forest is indicative of habitat quality, as this species prefers mature and relatively open forest stands. Flying squirrels can be found in the forested areas of the Southern Illinois University Edwardsville (SIUE) campus. Demographic features of this population and habitat use among forest patches were unknown. Artificial nest boxes were utilized to perform a mark-recapture study of the flying squirrel population as well as examine habitat use. Objectives were to obtain demographic information, and to create a predictive habitat model relating habitat characteristics to presence or absence of nest box materials using logistic regression. Study sites consisted of 145 randomized plots in three forest patches located within the SIUE campus, which were monitored November 2013 through October 2014. A model was generated for combined activity (nesting or feeding materials were present) at plots, which contained forest age, dominance of hard mast at a plot, tree density, topographic position, richness of the shrub layer, and the 90th percentile diameter at breast height. Habitat models were also generated for specified response variables of feeding material presence and nesting material presence. The top model for predicting feeding material presence in a nest box contained dominance of hard mast on a plot, richness of the shrub layer, and basal area of logs. The top model for predicting nesting material presence in a nest box contained the shrub layer stem count, roughness of the nest box tree bark, proximity to edge, cavity count, and the average hard mast dominance in the area surrounding the plot. Models tended to include characteristics regarding hard mast dominance and refugia, suggesting nest box use was influenced by avoidance of predation and food resource availability.</p>

<p>Amphibian populations have been declining at higher rates than bird and mammal populations. Agriculture, urbanization, including roads, and resource extraction continue to put pressure on all species. Roads in particular, are major sources of mortality. The Santa Cruz long-toed salamander (<i> Ambystoma macrodactylum croceum</i>), one of the most critically endangered species in the US, is one amphibian that is declining as a result of anthropogenic impacts, especially habitat loss and fragmentation due to urban development. Migration across roads puts these salamanders at risk from road-related death. This thesis quantified the rate of road mortality to these salamanders and other common amphibians during two A. m. croceum breeding-migration seasons in 2011&ndash;13 in a portion of the subspecies' range. Vehicular traffic was a major source of mortality to the salamander. Through traffic doubled the overall vehicle load on roads where the <i>A. m. croceum</i> migrated to and from breeding ponds. The Pacific chorus frog was also killed on the roads. This common species can be used as an indicator of road mortality risk for rarer amphibians. This study indicated that measures to reduce road mortality to the Santa Cruz long-toed salamander could include restricting vehicular traffic on roads adjacent to salamander ponds by limiting traffic to residential use only during breeding migrations, installing structures to protect <i>A. m. croceum</i> while crossing roads, and potentially assisting animals crossing roads at nighttime during the breeding migrations. </p>

<p> I estimated patterns of shorebird abundance and species diversity in the Colorado River Delta and Upper Gulf of California wetlands in order to determine the relative contribution of intertidal wetlands and non-tidal anthropogenic wetlands to support shorebird habitat use. Species richness varied from 15 to 26 species among sites and 29 species were detected across sites. Density during the peak migration month was higher at the anthropogenic wetland Cienega de Santa Clara (mean = 168 ind/ha, 95% C.I. 29-367), and the intertidal Golfo de Santa Clara (mean = 153 ind/ha, 95% C.I. 17-323). Anthropogenic wetlands (playa and lagoons) supported high abundance of shorebirds along with intertidal wetlands in the Colorado River Delta (mudflats). In contrast, intertidal wetlands farther south on the Sonoran Coast presented lower abundance but higher diversity of shorebird, likely as a result of the higher diversity of habitats (rocky shore, sandy beach, estuary). I modeled water management scenarios for the Cienega in order to determine the response of the dominant vegetation (southern cattail, <i>Typha domingensis</i> Pers.) and the area of the outflow pool below the marsh to different scenarios of water management. The model indicates that if the inflow rate is reduced below the current 4-5 m³ s^-1 the vegetated area of the Cienega that supports habitat for marsh birds would decrease in proportion, as would the area of the outflow pool in the Santa Clara Slough identified previously as shorebird habitat. Increases in salinity will also reduce the vegetated area due to the low salt tolerance of <i>T. domingensis</i>. In winter about 90% of inflow water exits the Cienega into the Santa Clara Slough due to low evapotranspiration contributing to inundate areas that are used by wintering and migrating shorebirds. Lastly, I explored the feasibility of using Vegetation Indices (NDVI and EVI) to model Yuma Clapper Rail detections in the Cienega de Santa Clara as well as the effects of adding other habitat variables and the presence of fire events in the performance of linear models based on NDVI. Both NDVI and EVI were positively related to the Yuma Clapper Rail detections. The relationship was weak to moderate, but significant (P &lt; 0.001), which suggests other factors besides the vegetation condition play an important role in the bird distribution pattern. A model including all the variability among years was a better predictor of the rails detected per transect, than models for fire and non-fire years. We did not find a significant effect from adding habitat features (water % or vegetation %), and we recommend to include variables at both microhabitat level and landscape level, relevant before and during the breeding season in order to increase the explanatory power of models.</p>

<p> Abstract not available.</p>

<p> Habitat fragmentation and loss is the primary driver of mammalian carnivore extinctions across the world. In the Santa Cruz Mountains of California, native carnivores navigate daily through a landscape highly impacted by human development and activities. The puma (<i>Puma concolor </i>) is the apex predator of this habitat, but it is susceptible to both direct and indirect influences of expanding human populations. Smaller predators are not only affected by anthropogenic disturbances, but also by intraguild competition with the more dominant pumas. </p><p> My dissertation utilizes new technologies to study the ecology and behavior of carnivores in a human dominated environment. In my first chapter, I catalogued puma behaviors in the wild using measurements recorded by accelerometers attached to the animals. I found that I could clearly distinguish movement from non-movement behavior, and that predation events had distinctive accelerometer signatures. The second chapter describes how I used movement data recorded by GPS (Global Positioning System) collars to evaluate puma behavioral responses to increasing development. Pumas primarily traveled nocturnally, and moved more often and further in areas of higher housing development. The increase in activity in human dominated landscapes could have major repercussions on the energetic expenditure of pumas living in fragmented areas. My third chapter addresses the impacts of human development and activities on the entire carnivore community. Combining passive and experimental observations using motion-detecting camera traps, I studied the spatiotemporal behavior of predators across a gradient of human influences. Mesopredator activity was restricted temporally in areas of high human use, and certain predators (e.g., pumas and foxes) were more sensitive to increasing development. </p><p> Lastly, education and outreach is an important component of carnivore conservation. In my fourth chapter, I describe results from a Facebook game I developed with collaborators. Players earned points by identifying wildlife species from camera trap photographs. I found that agreement among players was the most important determinant of accuracy, and that untrained Internet users could identify many wildlife species. The Internet is an emerging tool for outreach, and I hope my work encourages other ecologists to think creatively about incorporating citizen scientists into their research through social media.</p>

<p> Geophagy, the consumption of mineral soil, is believed to have several benefits for herbivores. Soils high in clay are often implicated in the detoxification of plant secondary metabolites. High mineral concentrations in soils may also provide nutrients that are poorly available from plants. Local observers report that snowshoe hares (Lepus americanus) use a lick in the foothills of the Brooks Range, Alaska. Using soil from this lick and other mineral supplements, I conducted a series of feeding trials on captive snowshoe hares fed felt-leaf willow (Salix alaxensis) or a formulated ration to determine whether geophagy resulted in a physiological benefit and, if so, which soil constituents are therapeutic. When fed willow leaves, hares ate more and lost less weight when they had access to soil. Access to soil increased sodium intake and dietary ratios of sodium to potassium in hares fed willow. Soil consumption resulted in higher calcium to phosphorous ratios for both diets. Across diets, higher sodium to potassium and lower calcium to phosphorus ratios corresponded to reduced weight loss. Access to pure calcium carbonate resulted in reduced weight loss in hares fed winter dormant willow twigs, suggesting that carbonates may also be an important component of this lick. </p>