Animal foraging from an individual perspective: an object orientated model

A model system, HOOFS (Hierarchical Object Orientated Foraging Simulator), has been developed to study foraging by animals in a complex environment. T he model is implemented using an individual-based object-orientated structu re. Different species of animals inherit their general properties from a ge neric animal object which inherits from the basic dynamic object class. Eac h dynamic object is a separate program thread under the control of a centra l scheduler. The environment is described as a map of small hexagonal patch es, each with their own level of resources and a patch-specific rate of res ource replenishment. Each group of seven patches (0th order) is grouped int o a Ist order super-patch with seven nth order super-patches making up a n + 1th order super-patch for n up to a specified value. At any time each ani mal is associated with a single patch. Patch choice is made by combining th e information on the resources available within different order patches and super-patches along with information on the spatial location of other anim als. The degree of sociality of an animal is defined in terms of optimal sp acing from other animals and by the weighting of patch choice based on soci al factors relative to that based on food availability. Information, availa ble to each animal, about patch resources diminishes with distance from tha t patch. The model has been used to demonstrate that social interactions ca n constrain patch choice and result in a short-term reduction of intake and a greater degree of variability in the level of resources in patches. We u sed the model to show that the effect of this variability on the animal's i ntake depends on the pattern of patch replenishment. (C) 1998 Elsevier Scie nce B.V. All rights reserved.