A general angular regression model for the analysis of data on animal movement in ecology

The paper investigates angular regressions that express the angles of an animal's motion in terms of time varying directions and distances to environmental features that could influence its displacement. The mean direction proposed is a compromise between several possible targets. Conditions for the identifiability of the regression parameters are provided. Maximum likelihood estimators for the parameters are derived under two von Mises error structures. Robust sandwich estimators of the parameter variance-covariance matrix are obtained. The statistical methodology proposed is first used to reanalyse a classical data set on periwinkle movement. A second application investigates how bison trails are shaped by meadows and canopy gaps in Saskatchewan's Prince Albert National Park.