A simulation model of ruminant foraging strategies

The emergent properties of populations are influenced by characteristics and spatial location of individuals. However, differences between individuals within populations are often ignored in ecological models. The variability of characteristics within a population and the heterogeneity of the environment can lead to divergence in efficiency with which animals forage. I developed a simulation model of foraging behavior with explicit representation of habitat and animal variability.;A series of experiments examined the influence of (1) consumptive ability; (2) perceptual ability; and (3) decision rate on foraging movements, food-seeking ability, and foraging efficiency. Another set of experiments examined the importance of (1) biomass per plant, (2) variability of biomass per plant, (3) bite size, (4) variability in bite size, (5) spatial distribution of food, and (6) density of forage, to foraging efficiency. A step-by-step record of the foraging path was kept for each simulation.;The forager turned less as its lateral reach increased, but moved in an increasingly complex pattern as its perceptual field increased. Multi-dimensional scaling of paths revealed trends in response to changes in consumptive and perceptual abilities. Chernoff faces revealed consistent patterns in several variables. Regression analysis revealed significant linear relationships between path variables and the size of consumptive and perceptual fields.;The forager encountered and selected biomass in distributions significantly different than was available. Changes in the size of the consumptive field had little impact on the utilization of resources. When the perceptual field was larger than the consumptive field the forager consistently encountered and selected biomass in significantly different distributions than was available. The forager's decision rate had no affect on the distribution of biomass selected.;The mean rate of dry matter intake ranged from 6 g/min to over 12 g/min. The mean size of plants, variability in size, mean bite size, variability in bite size, and the spatial distribution of plants available to the forager all exerted a greater influence on foraging performance than did total available biomass. The model demonstrated an optimum perceptual distance beyond which the forager wasted time searching for better short-term gains.