Abstract
A model is presented of optimum body sizes at different ambient temperatures. Selection is considered to optimize the difference between foraging profit per time and maintenance energy costs per time, scaled to body size. Two different scaling functions are considered: one maximizes the amount of activity that an individual can perform, and the other maximizes the length of time an individual can survive on the profit gained in a given period of foraging. With both scaling functions, optimum size increases as ambient temperature decreases.
