In a desert area with abundant annual plants the largest feeding guild was grammivores (nine species). In an area with few annual plants, the largest feeding guild was omnivores (eight species). Within a guild there is little overlap in body length of workers. Species in which there was overlap in body length of workers exhibited marked differences in diet and seasonal activity. Variation in precipitation and productivity between years resulted in differences in seasonal activity, hence considerable variation in the structure of the ant community through time.