This vector field was produced from the data described in Brillinger, D.R., Preisler, H.K., Ager, A.A. and Kie, J.G. "An exploratory data analysis (EDA) of the paths of moving animals". J. Statistical Planning and Inference 122 (2004), 43-63, using the methods of Brillinger, D.R., "Learning a potential function from a trajectory", Signal Processing Letters. December (2007).