FOOD BIOTECHNOLOGY LAB REPORT

Food Biotechnology Lab Report

Abstract

The theory of optimal foraging and its relation to central foraging was examined by using the beaver as a model. Beaver food choice was examined by noting the species of woody vegetation, status (chewed vs. not-chewed), distance from the water, and circumference of trees near a beaver pond in North Carolina. Beavers avoided certain species of trees and preferred trees that were close to the water. No preference for tree circumference was noted. These data suggest that beaver food choice concurs with the optimal foraging theory (Iyer, 2009,, 8).

Food Biotechnology Lab Report

Introduction

In this lab, we explore the theory of optimal foraging and the theory of central place foraging using beavers as the model animal. Foraging refers to the mammalian behavior associated with searching for food. The optimal foraging theory assumes that animals feed in a way that maximizes their net rate of energy intake per unit time (Pyke et al. 1977). An animal may either maximize its daily energy intake (energy maximizer) or minimize the time spent feeding (time minimizer) in order to meet minimum requirements. Herbivores commonly behave as energy maximizers (Belovsky 1986) and accomplish this maximizing behavior by choosing food that is of high quality and has low-search and low-handling time (Pyke et al. 1977) (Iyer, 2009,, 8).

The central place theory is used to describe animals that collect food and store it in a fixed location in their home range, the central place (Jenkins 1980). The factors associated with the optimal foraging theory also apply to the central place theory. The central place theory predicts that retrieval costs increase linearly with distance of the resource from the central place (Rockwood and Hubbell 1987). Central place feeders are very selective when choosing food that is far from the central place since they have to spend time and energy hauling it back to the storage site (Schoener 1979).

The main objective of this lab was to determine beaver (Castor canadensis) food selection based on tree species, size, and distance. Since beavers are energy maximizers (Jenkins 1980, Belovsky 1984) and central place feeders (McGinley and Whitam 1985), they make an excellent test animal for the optimal foraging theory. Beavers eat several kinds of herbaceous plants as well as the leaves, twigs, and bark of most species of woody plants that grow near water (Jenkins and Busher 1979). By examining the trees that are chewed or not-chewed in the beavers' home range, an accurate assessment of food preferences among tree species may be gained (Jenkins 1975). The purpose of this lab was to learn about the optimal foraging theory. We wanted to know if beavers put the optimal foraging theory into action when selecting food (Boucek, 2008,, 9).

We hypothesized that the beavers in this study will choose trees that are small in circumference and closest to the water. Since the energy yield of tree species may vary significantly, we also hypothesized that beavers will show a preference for some species of trees over others regardless ...