Ecology aims to understand the links between processes and patterns in the natural world. Scale plays an integral role, because processes at one scale, large or small, can shape patterns observed at disparate scales. Ecological research typically considers scale in terms of space, time, and biotic organization, and across these three dimensions no single scale provides a definitive lens through which to consider any given ecological phenomenon. This is because the motivations of the observer inform which scales are meaningful. In particular, the diverse goals set by wildlife conservation and management efforts can cover a wide range of scales in space, time, and organization.Modern conservation faces the challenge of maintaining biodiversity and ecosystem function amid widespread habitat alteration and climate change. The challenge is intensified in arid environments, where resources are scarce and ephemeral in space and time, and plants and animals are often existing at their physiological limits for factors like temperature and water. Wildlife conservation in arid environments can benefit from strategies that increase species’ resilience, providing the opportunity to adapt as changes occur. Effective approaches include protecting habitats that serve as climate refugia or facilitate movement, increasing permeability for mobile species, supplementing critical resources, and undertaking captive breeding, reintroduction, and translocation of particularly vulnerable species. My dissertation examines multi-scale approaches to wildlife ecology and conservation in arid environments, emphasizing how these frameworks can inform our understanding of human impacts on wildlife and guide effective conservation strategies. Chapter 1 explores the influence of development and urbanization on bobcats (Lynx rufus) in San Diego County, focusing on individual and population-level space use. Results showed that at the individual level, bobcats prefer areas characterized by low elevation and low development intensity. In a region like San Diego County where development is concentrated at lower elevations along the western coastline, this suggests constraints on preferred habitats for this species. At the population level, we observed a contrasting pattern, where bobcat densities were higher in developed areas relative to wildland spaces. This suggests that, while individual animals select against development, patterns of population density are governed by development-related movement barriers. Recognizing these contrasting relationships across scales of organization can inform future conservation action in this region to ensure wildlife persistence in developed areas, including identifying movement corridors and prioritizing areas for preservation. Chapter 2 is set in the Sonoran Desert in southwest Arizona and investigates seasonal patterns of post-translocation mortality risk for the Sonoran pronghorn (Antilocapra americana sonoriensis), a federally endangered ungulate that has been the focus of a long-term captive breeding and reintroduction program. At the scale of the study area, long-term drought conditions elevated mortality risk in the fall, winter, and spring, while increased experience reduced mortality risk in the early summer and summer monsoon seasons. At the scale of individual space use, increased human footprint elevated mortality risk year-round, and a lack of water access further increased mortality risk in summer months. Mortality risk for translocated Sonoran pronghorn is influenced by both large-scale climatic conditions and small-scale habitat contexts. A consideration of both scales can provide insight for informing effective translocation practices in current and future reintroduction areas. Chapter 3 remains in the Sonoran desert but expands from a single-species focus to consider the large mammal community, exploring seasonal variation in occurrence and interactions at managed water sources. As expected, single-species occupancy at waters varied seasonally and was generally higher in summer months, confirming that these waters represent an important resource to multiple members of the large mammal community. Although species occupancy was elevated across water sites during the summer, similar seasonal patterns did not necessarily equate to high predicted co-occurrence, refining expectations for species overlap at sites. At a finer temporal scale we measured both potential and direct interactions. Potential for interactions to occur increased in summer months, as did direct interactions. Direct species interactions were higher as a function of relative species abundance and high antagonism class, but were also impacted by drought severity in the summer monsoon and fall-winter seasons. Active water management is likely to become more prevalent as conditions in the Sonoran Desert trend hotter and more prone to periods of severe drought. As desert ecosystems continue to experience anthropogenic change, thoughtful approaches to water management that account for the influence on species interactions and other unintended effects will be valuable for ensuring that this strategy achieves desired conservation and management objectives. These research efforts integrate multiple scales in space, time, and organization to deepen our understanding of human impacts on wildlife and inform conservation strategies in arid environments. When conducting observational ecological studies in natural systems, describing patterns is a simpler task than uncovering underlying processes. By considering multiple scales in space, time, and organization, we can derive insight into the processes that underlie patterns of interest.

ABSTRACT Monitoring physical and biological conditions in the open ocean is an inherently difficult task, particularly when monitoring toxic and harmful compounds. Efforts to use biomonitor species to measure and assess ocean and organismal health require considerable information on habitat use and other life history characteristics to contextualize and interpret contaminant data. A large proportion of biomonitoring research focuses on a single species, a single site, and/or a small range (i.e. 1-3) of contaminant classes. While informative, the scope of such studies can limit their applicability, which is concerning as data suggests the abundance of organic and heavy metal contaminants in the ocean is increasing. Contaminants can have sub-lethal effects that affect population viability, and new, unknown contaminants enter the environment with little knowledge of their possible effects and limited ability to monitor these emerging contaminants. Seabirds serve as effective biomonitors for contaminants for multiple reasons. First, seabirds feed at high trophic levels, where toxicants are biomagnified. Because most seabird species are long-lived, birds may bioaccumulate toxicant types into tissues (e.g., fat) over a lifetime, much like humans. Contaminants also accumulate in seabird tissues that can be sampled non-lethally and at low cost, including blood, feathers, and non-viable eggs. Thus, it is also easy to assess the sub-lethal effects of low, but chronic levels of contaminants on a variety of ecological parameters, especially when paired with long-term datasets. Additionally, many seabird tissues have enough volume with which to test for multiple contaminant classes in a single sample. Lastly, seabirds exhibit high breeding site fidelity, so individuals can be sampled and re-sampled with regularity. My research explores how seabirds may be used as biomonitors for a rapidly-changing ocean environment. In Chapter 1, I show that seabird tissues can be used to indicate the magnitude and extent of a wide range of contaminants at the regional scale in the Southern California Bight. In contrast to single species, single site monitoring, regional assessments maximize the ability to use biomonitoring efforts to meet mandated monitoring objectives, prioritize site remediation, and trace the dispersal and uptake of toxicants in marine food webs. The results suggest at least one species, the California least tern (Sterna antillarum browni), may be a robust indicator of contaminant patterns in this region. Chapter 2 investigates blood mercury concentrations as a function of foraging distribution in western gulls (Larus occidentalis) nesting at three colonies off the California and Oregon coast. We found that ocean-foraging gulls had elevated mercury concentrations and also lower fidelity to geographic foraging areas, confirming work that suggests aquatic foragers have greater exposure to methylmercury. As mercury exposure and likely exposure to other contaminants differs across the land-sea gradient, species that forage in marine and terrestrial environments may be used to better understand the ecological consequences of contaminant-associated diet. Chapter 3 uses an established nontargeted approach to examine the presence and patterns of legacy and frequently unmonitored halogenated organic compounds in three albatross species that range the North Pacific. The majority of contaminants we found are currently unmonitored, which demonstrates the extent of chemical contamination beyond urbanized coastal areas to remote coastal regions. We also found support for previous research that suggests differences in broad-scale foraging areas impact contaminant abundance among these three species.

Climate shifts and increasing variability are anticipated to alter ocean systems, significantly impacting marine ecosystems as well as the communities, businesses, and fisheries reliant on them. Apart from the gradual effects of climate change (i.e. long-term ocean warming), marine organisms and fisheries are also experiencing episodic extreme oceanic warming events, known as marine heatwaves (MHWs), that can push ecosystems into new environmental conditions, further challenging already stressed social-ecological systems. The impact of MHWs may be particularly pronounced for highly migratory pelagic species who shift their distributions during anomalous events in response to unfavorable conditions, which can lead to ecological disruptions, such as predators being separated from their prey, and economic disruptions if target fish populations decline or move out of the range of the fishers who catch them. Understanding and predicting how such disruptions will affect both ecological and human communities will enhance the ability of conservation and management efforts to keep pace with future MHWs as they unfold.Species distribution models (SDMs) have emerged as a fundamental tool to predict how species will respond to changing environmental conditions and have served a critical role in marine conservation and management. Despite their known utility, there is considerable uncertainty as to how useful SDM predictions can be given the current and continued changes in ocean conditions. Digital and technological advancements have greatly expanded the volume and diversity of data available for developing SDMs, which, when combined, can offer complementary information on species distributions and improve model inference and prediction. Development of data integration for SDMs has advanced over the last decade, showing great potential in enhancing model performance as they are able to account for data-specific biases while retaining the strengths of each dataset. However, despite these advantages, such applications to integrate disparate data sources have been scarce in marine systems, particularly for highly migratory pelagic species, limiting our knowledge on how best to leverage diverse data sources for modeling species distribution under a changing climate. My research focuses on modeling species and fishery spatiotemporal distributions and exploring the capacity of data integration in improving model performance under MHWs. In Chapter 1, we take a bi-coastal approach to explore how MHW properties influence the redistribution of U.S. pelagic fisheries. Our study provides the first evidence that MHW size, rather than MHW intensity or duration, exerts the largest impact on fishing vessels, with southern regions on both coasts losing fishing grounds as size increased. The extent of fleet displacement in response to MHWs, however, varies between coasts, as the Atlantic longline fleet displaced farther in southern regions whereas peripheral regions of the Pacific troll fleet shifted farther. Our results suggest that MHWs drive differential impacts across fishing fleets and regions, and characterizing how fleets will respond can be used to identify regions of resilience or vulnerability in the face of future MHW events. Chapter 2 evaluates approaches to synthesizing multiple data types for SDMs, comparing traditional data pooling and ensemble techniques to a model-based integrative framework using diverse data sources for blue sharks across the north Atlantic Ocean. Results revealed that integrated SDMs, which account for data-specific biases and seasonal variability, generate more accurate and ecologically realistic predictions, though they are computationally intensive. Our findings highlight trade-offs in data integration techniques and the importance of leveraging diverse data sources for marine conservation and management. Building on these findings, chapter 3 seeks to explore how model-based integration improves spatiotemporal forecasts for an important fishery species, albacore tuna, during a period of unprecedented MHWs in the northeast Pacific Ocean. Results indicate that traditional SDMs generally struggle with predictive accuracy and realism as environmental novelty increases, while integrated SDMs (iSDMs) maintain greater predictive skill and ecological realism. The findings suggest that leveraging diverse data sources through appropriate integration methods is crucial for generating accurate ecological forecasts and supporting climate-ready management and conservation strategies as episodic climate events become more prevalent.