Understanding the effects of environmental variability on demography in species with complex life histories through integrated population modeling

Abstract

Understanding the spatio-temporal variability in demography offers insight into factors underlying the dynamics and viability of wildlife populations. However, sparse monitoring data or persistent knowledge gaps can make it difficult to estimate vital rates for species with complex life histories. Even more challenging is identifying causal mechanisms that explain demographic patterns for long-lived, adaptive top predators due to the complexities of obtaining data about natural environmental variability or anthropogenic stressors at ecological scales most relevant to the population of interest. These challenges can be particularly acute in situations where the need for information is greatest; namely, for populations that are small, depleted, or declining and in need of conservation and management. Integrated population models (IPMs) that combine disparate data sources have emerged as an important tool for maximizing available information to improve the estimation of vital rates, abundance, and viability of wildlife populations. The research presented here includes three case studies using data integration and hierarchical Bayesian state-space models to examine the effects of environmental conditions on the demography and viability of marine mammals and seabirds. First, I present a novel multi-event open-population model that extends nest survival and abundance modeling approaches to accomodate data where nest age, state, and fate may be unknown. I apply this model to Pigeon Guillemots (Cepphus columba) to provide the first estimates of fecundity for this indicator species in Puget Sound, Washington (Chapter 2) to facilitate future integrated population modeling using data collected by a community science program. Second, I developed an IPM to examine demographic and environmental factors contributing to divergent abundance trends observed across the range of the Endangered western distinct population segment of Steller sea lions (Eumetopias jubatus) in Alaska (Chapters 3-4). Third, I developed an IPM to examine environmental drivers of demography and viability for the Endangered Cook Inlet beluga whale in Alaska (Chapter 5). Unifying themes of this work include developing complex demographic models to reduce uncertainty in support of conservation and confronting the challenges of making inference about the effects of environmental variability at spatio-temporal scales relevant to long-lived, adaptive top predators living in dynamic and changing ecosystems.