Track annotation: Determining the environmental context of movement through the air

Volant organisms are adapted to atmospheric patterns and processes. Understanding the lives of animals that inhabit this aerial environment requires a detailed investigation of both the animal's behavior and its environmental context-i.e., the environment that it encounters at a range of spatial and temporal scales. For aerofauna, it has been relatively difficult to observe the environment they encounter while they move. Large international efforts using satellite and weather model reanalysis now provide some of the environmental data on atmospheric environments throughout the globe. Track annotation-the approach of merging the environmental data with the movement track measured via telemetry-can be conducted automatically using online tools such as Movebank-Env-DATA or RNCEP. New parameterization approaches can use environmentally annotated tracks to approximate specific atmospheric conditions, such as uplift and tail wind, which are not typically observed at the exact locations of the movement, but are critical to movement. Reducing the complexity of movement to single-dimensional characteristic (such as flight speed, elevation, etc.) and defining the temporal scope of the movement phenomenon in the focus of the analysis (seasonal, daily, minutely, etc.) makes it possible to construct empirical models that explain the movement characteristic as driven by the environmental conditions during flight, despite the highly dynamic, complex, and scale-dependent structures of both the flight path and atmospheric variables. This chapter will provide several examples for such empirical movement models from different species of birds and using several resources for atmospheric data.