LTREB: Pace of life and differential migration in changing environments

Colorado State University, Fort Collins CO

Investigators

Abstract

For millennia, humans have been fascinated by the long-distance migrations that many animals undergo to find food, reproduce, and survive. In recent decades, scientists have observed that more and more animals are not migrating as far as their ancestors did. Why is it that some individuals stop their migration short while others continue to adopt traditional, long-distance migrations? What are the consequences of these changing behaviors for migratory species, and how does this impact human societies? Using a unique long-term study of brant geese, the researchers will address these questions by studying the dual influence of climate change and an individual’s reproductive history (how many babies they have reared to date) on migration distance, and the impact of migratory decisions on future chances of survival and reproduction. The team will then quantify the contribution of each type of migration behavior to the overall abundance of brant geese. Brant geese affect coastal economies via their role as primary grazers of eelgrass along the Pacific Coast, the same habitat that serves as the rearing ground for a myriad of fish and shellfish species. Without an abundance of brant to maintain healthy beds of eelgrass, and a solid understanding of the factors affecting brant abundance, the fishing industries that rely on eelgrass estuaries could suffer. While carrying out the study, the team will train a varied group of students in STEM fields. The team will also develop open educational materials covering wildlife sampling techniques and models for K-12 students. Like other taxa, many brant are stopping their seasonal migration short and wintering at high latitudes as the climate warms and as habitats further south are damaged by humans. But many individuals continue to invest in traditional long-distance migrations to southern latitudes, creating a divergent pattern of migration tactics within brant populations over time. By leveraging a long-term study of brant in Alaska, the researchers will test whether environmental change is allowing individual brant to choose equally from a broad range of migration strategies, or if environmental change is directionally favoring a particular migration strategy (long- vs. short-distance) associated with life-history tempo (fast vs. slow reproductive investment and lifespans), as measured via the currency of lifetime evolutionary fitness. Modeling will also reveal the contributions of individual migration tactics to brant population viability, and the impact of brant populations on the ecosystems they graze. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.