Geoscience Reference
In-Depth Information
Figure 5.3 Relationship between 15 N signatures of the diet of equilibrated plasma in black bears
(Ursus americanus, (•) and polar bears (U. maritimus, (
m
). Copyright 1996 Hilderbrand et al.
Reprinted by permission of the Canadian Journal of Zoology.
THE ROLE OF FORAGING THEORY IN UNDERSTANDING FOOD HABITS
Most animals exploit a narrower range of food items than they are capable of
consuming. In an effort to understand the constraints that may determine diet
width, ecologists have organized their evaluations of food selection into a body
of theory called optimal foraging theory (Schoener 1986; Begon et al. 1996;
Perry and Pianka 1997). Two distinct approaches have developed to address
this issue. The first considers that an animal selects among various food or prey
items that are distributed in some fashion (e.g., clumped) throughout a gener-
ally suitable habitat. The second approach examines how animals discriminate
among various patches of habitat that vary in productivity and suitability
(Morrison et al. 1992) and can be viewed as an evaluation of habitat selection.
Early efforts to understand diet width relied on evaluating potential food
items in terms of cost (search and handling time) and benefit (energy)
(MacArthur and Pianka 1966; Charnov 1976). According to the basic
assumptions of foraging theory, an animal should have a diet that maximizes
energy intake and minimizes time to obtain nourishment (Schoener 1971). As
Search WWH ::




Custom Search