Inferring environmental drivers of animal migration path choice

Keywords: Movement ecology, trajectory similarity, avian migration, GPS trajectories, environmental conditions
Session Type: Virtual Paper Abstract
Day: Sunday
Session Start / End Time: 2/27/2022 02:00 PM (Eastern Time (US & Canada)) - 2/27/2022 03:20 PM (Eastern Time (US & Canada))
Room: Virtual 17

Abstract

Migration enables animals to exploit spatially discrete habitats to accomplish various biological objectives (e.g., breeding, reproduction). During migration, animals respond to environmental variation by altering their path choice. We develop a trajectory-similarity-based hierarchical clustering framework to evaluate variability in movement patterns of migratory birds. The proposed framework leverages trajectory-similarity analysis to reveal the relationships between migration paths and the underlying environmental factors influencing movement choices of migratory turkey vultures (Cathartes aura) in North America. Multiple commonly used trajectory-similarity measures are integrated using a hierarchical clustering approach. These include Fréchet distance, dynamic time warping (DTW), Hausdorff distance, longest common subsequence (LCSS), and normalized weighted edit distance (NWED). From tracking data of 13 turkey vultures during their migration seasons between 2005 and 2020, fall and spring migration clusters are identified. Using trajectory annotation with Movebank EnvDATA, we characterize the obtained clusters based on the environmental conditions that were “used” by the turkey vultures at recorded track points. Environmental factors considered in this study include thermal uplift, air temperature, vegetation greenness, orographic uplift, wind patterns, and precipitation. We contrast the characteristics of the clusters against the background distribution of the same environmental factors (i.e., the “available” conditions). The outcome suggests that except for orographic uplift, all other aforementioned environmental factors seem to contribute to turkey vultures’ migration-path choice. In addition, different preferences are manifested among clusters even for the same factor. The proposed framework can be applied to analyze movement paths of any migratory species.