A Spatially-Varying Stochastic Differential Equation Model for Animal   Movement
  Animal movement exhibits complex behavior which can be influenced by unobserved environmental conditions. We propose a model which allows for a spatially-varying movement rate and spatially-varying drift through a semiparametric potential surface and a separate motility surface. These surfaces are embedded in a stochastic differential equation framework which allows for complex animal movement patterns in space. The resulting model is used to analyze the spatially-varying behavior of ants to provide insight into the spatial structure of ant movement in the nest. 
James C. Russell, Ephraim M. Hanks, Murali Haran, David P. Hughes
stat.AP