From Mark-Resight to Management: Bayesian Hierarchical Models for Endangered Bird Populations

Abstract

Producing reliable estimates of demographic rates is critical to our understanding of wildlife population dynamics and can provide valuable information for prioritizing conservation and management efforts. Precise and unbiased estimates are challenging to obtain when monitoring data are sparse, knowledge gaps are pervasive, or model assumptions are violated. This is often the case for species of conservation concern, which may be poorly understood and difficult to monitor. Bayesian hierarchical models are particularly useful for estimating demographic rates because they separate imperfect observation processes from the underlying biological processes, especially when combined in an integrated framework that leverages multiple data sources for increased precision and parameter identifiability. Here I present three case studies using Bayesian hierarchical models to better understand the demography of threatened birds, with particular contributions to mark-resight and integrated population modeling. In Chapter 2, I addressed a common but poorly understood problem in mark-resight studies of open populations: partial mark loss and degradation. I present a novel approach to sampling latent states in a Markov Chain Monte Carlo framework using a backtracking algorithm, and I apply this approach in the context of a multi-event model to the Oregon Vesper Sparrow (Pooecetes gramineus affinis) in South Puget Sound, Washington, USA. The results from this model constitute some of the first estimates of age-specific survival and dispersal rates for this species of conservation concern. In Chapter 3, I developed a novel multi-site integrated population model (IPM) to better understand the population dynamics of Streaked Horned Larks (Eremophila alpestris strigata) in South Puget Sound, Washington. These estimates will inform future habitat management and a planned reintroduction effort, and the multi-site framework addresses a critical gap in modeling small populations monitored over fragmented landscapes. In Chapter 4, I developed an IPM to examine the impact of a cryptic threat, bycatch in commercial fisheries, on the population dynamics of Atlantic Yellow-nosed Albatross (Thalassarche chlororhynchos). Results from this model will motivate ongoing monitoring of Atlantic Yellow-nosed Albatross and seabird bycatch in the South Atlantic and inform fisheries regulation decisions. Broadly, the work I present here makes contributions to the development of complex demographic models with the goal of supporting conservation and management decisions by quantifying and reducing key uncertainties in the population dynamics of threatened species.