Food and Populations

Animal populations increase to limits of food and space availability in a densitydependent pattern. Animal populations are groups of individuals with different body sizes and food requirements. The adequacy of food supplies for any group of animals in the wild or in captivity depends on the number of animals and their demands for energy and nutrients in the prevailing environmental conditions. A small fraction of the energy available in a population of plants or prey is consumed by the next trophic level because energy is expended for non-productive processes at each level and because the consumer may only capture a portion of the production. Weather drives changes in primary plant production and secondarily affects risks of debility and death for animals. Environmental extremes can increase the vulnerability of small populations to greater demands (e.g., predation) and the risk of large populations to starvation.