The effects of animal density, spatial heterogeneity, and diversity in individual responses to population density on daily time and energy budgets were studied by means of a simple time-energy model. The cost of interactions between individuals was expressed as a reduction of the time that an animal may spend for feeding and other activities. The value of daily production rate would decrease with the increase in density and/or in food availability. In this case, production rate would be a convex function of population density as well as of individual tolerance to the presence of other animals and the size of individual range. Therefore, under unfavourable conditions (high mean density and/or low mean food availability) both spatial heterogeneity and diversity in individual responses to the presence of neighbouring animals would lead to an increase in the mean production rate.