Research
Seasonality, migration, and the consequences of phenological change
Migration allows animals to take advantage of favorable conditions in seasonal environments. Its success depends on timing migration and breeding to match the availability of food and other resources. Changing environmental conditions are now substantially altering the timing of these seasonal events (phenology), presenting challenges for migratory species. Our research asks what facilitates and constrains birds' ability to track changes in seasonality and why these responses differ among species and populations. Leveraging a hierarchical Bayesian modeling approach, we combine millions of bird observations from large-scale participatory science projects and structured monitoring with environmental data to study seasonal dynamics across the world. We investigate whether birds have reliable environmental cues indicating favorable conditions at migratory destinations and how physiological demands and other constraints limit the set of viable migratory strategies. We are particularly interested in how phenological change disrupts interactions within and across trophic levels and the consequences this has for the persistence of populations and the seasonal composition of ecological communities.
Characterizing and predicting population responses to a changing world
Given the inherent complexity and multiscale nature of natural systems, understanding and predicting population responses to environmental change is challenging. The processes governing short-term population fluctuations may differ from those driving sustained change, and responses can vary even among populations of the same species. Our research combines an expanding set of ecological data resources with advances in AI and hierarchical statistical modeling to identify the processes shaping population dynamics and the conditions under which they can be reliably predicted. Current NASA-funded work uses satellite imagery from across the range of Pacific walrus to characterize their responses to a changing Arctic. Through this work and other projects, including those focused on Antarctic penguins, we are drawing on rapid technological and analytical advances to develop a methodological foundation for satellite-enabled population ecology. We are also working to understand the factors that determine, and fundamentally limit, the predictability of population dynamics, taking both theoretical and empirical perspectives. We ask how biological and environmental context constrain and facilitate our ability to forecast ecological futures and where limits to predictability coincide with rapid environmental change and conservation concerns.
Phenotypic variation across scales and community assembly processes
Understanding how and why organisms differ in their traits is central to the fields of ecology and evolutionary biology. While biodiversity research has traditionally focused on differences among species, substantial variation also exists among individuals and populations within species. This variation has important implications for how organisms interact with their environment and one another, with consequences for species coexistence and the resilience of ecological systems. Our research aims to understand what processes generate and maintain phenotypic variation across scales and how that variation shapes the assembly and organization of ecological communities. We integrate large-scale data from hundreds of bird species across the Americas, derived from monitoring programs and museum collections, to understand why morphological and reproductive traits vary within and among populations. Using a set of novel quantitative tools, we investigate how environmental conditions and functional tradeoffs shape the distribution of traits across species' ranges and what this variation reveals about the roles of environmental filtering and niche partitioning in the assembly of ecological communities.
