Knowledge Bank

Aerial migrations are historically difficult to observe and quantify, especially the environment in which these migration take place. However, with increasingly accurate tracking methods and international datasets containing remote sensing and weather renalyses, it is becoming easier to observe this environment and find the conditions that mostly affect the migrants. Track annotation is the method of combining the tracking data with the environmental data, and can be used to create models of the animals’ movement. I performed a track annotation of Swainson’s thrush and created an empirical model based on the environmental conditions that mostly affect the flight. A Swainson’s thrush (Catharus ustulatus) is a small songbird that migrates from northeastern North America to Central and South America in the winter. This annual migration involves a 1000-kilometer trip across the Gulf of Mexico. Little is known about the details surrounding this annual flight, including the variables that affect the flight itself. In a National Science Foundation (NSF) funded experiment, the thrushes are tracked by a radio transmitter which allows us to record arrival and departure timestamps of the transGulf flight. The Environmental-Data Automated Track Annotation (Env-DATA) system—a data exploration system developed through Movebank (www.movebank.org) and The Ohio State University allows us to link the movement track with data from global and regional weather reanalysis models and remote sensing. I annotated the movement tracks with several different environmental variables and followed a hierarchal process to build a series of empirical movement models. I concluded that the combination of boundary layer height and wind speed most strongly affect the flight.