Modern ecological research often involves the comparison of the usage of habitat types or food items to the availability of those resources to the animal. Widely used methods of determining preference from measurements of usage and availability depend critically on the array of components that the researcher, often with a degree of arbitrariness, deems available to the animal. This paper proposes a new method, based on ranks of components by usage and by availability. A virtue of the rank procedure is that it provides comparable results whether a questionable component is included or excluded from consideration. Statistical tests of significance are given for the method. The paper also offers a hierarchical ordering of selection processes. This hierarchy resolves certain inconsistencies among studies of selection and is compatible with the analytic technique offered in the paper. Central to the study of animal ecology is the usage an animal makes of its environment: specifically, the kinds of foods it consumes and the varieties of habitats it occupies. Many analytic procedures have been de- vised to treat data on the usage of such resources, particularly in relation to information on their avail- ability to the animal, for the purpose of determining "preference." The objectives of this report are to de- scribe the problem of determining preference by com- paring usage and availability data, to illustrate a seri- ous shortcoming in the routine application of most procedures for comparing these data, and to suggest a new method that resolves this difficulty. The pro- posed technique results in a ranking of the components on the basis of preference, and permits significance tests of the ranking.

/pdf/the-comparison-of-usage-and-availability-measurements-for-4iriiv715a.pdf

The comparison of usage and availability measurements for evaluating resource preference

Methods for analysing fish stomach contents are listed and critically assessed with a view to their suitability for determining dietary importance—this term is defined. Difficulties in the application of these methods are discussed and, where appropriate, alternative approaches proposed. Modifications which have practical value are also considered. The necessity of linking measurements of dietary importance to stomach capacity is emphasized and the effects of differential digestion upon interpretation of stomach contents outlined. The best measure of dietary importance is proposed as one where both the amount and bulk of a food category are recorded.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1095-8649.1980.tb02775.x

Stomach contents analysis—a review of methods and their application

Natural history is replete with observations on feeding, yet only recently have investigators begun to treat feeding as a device whose performance­ as measured in net energy yield/feeding time or some other units assumed commensurate with fitness-may be maximized by natural selection (44, 1 13, 135, 156, 181) . The primary task of a theory of feeding strategies is to specify for a given animal that complex of behavior and morphology best suited to gather food energy in a particular environment. The task is one, therefore, of optimization, and like all optimization problems, it may be tri­ sected: 1. Choosing a currency: What is to be maximized or minimized? 2. Choosing the appropriate cost-benefit functions: What is the mathematical form of the set of expressions with the currency as the dependent variable? 3. Solving for the optimum: What computational technique best finds ex­ trema of the cost-benefit function? In this review, most of the following section is devoted to possible answers to the first problem. Then four key aspects of feeding strategies will be considered: (a) the optimal diet, (b) the optimal foraging space, (c) the optimal foraging period, and (d) the optimal foraging-group size. For each, possible cost-benefit formulations will be discussed and compared, and predictions derived from these will be matched with data from the literature on feeding. Because the third problem is an aspect of applied mathematics, it will be mostly ignored. Throughout, emphasis will be placed on strategic aspects of feeding rather than on what Holling (75) has called "tactics."

Theory of Feeding Strategies

ARTICLES Organic Fluorine Chemistry: C. G. Krespai.................................. Expanding rapidly, the science of these compounds has assumed both theoretical and practical importance. The Biological Synthesis of Cholesterol: K. Bloch .............................. Predation, Body Size, and Con-mposition of Plankton: J. L. Brooks and S. I. Dodson ... The effect of a marine planktivore on lake plankton illustrates theory of size, competition, and predation. 7

https://science.sciencemag.org/content/sci/150/3692/28.full.pdf

Predation, Body Size, and Composition of Plankton

Beginning with Emlen (1966) and MacArthur and Pianka (1966) and extending through the last ten years, several authors have sought to predict the foraging behavior of animals by means of mathematical models. These models are very similar,in that they all assume that the fitness of a foraging animal is a function of the efficiency of foraging measured in terms of some "currency" (Schoener, 1971) -usually energy- and that natural selection has resulted in animals that forage so as to maximize this fitness. As a result of these similarities, the models have become known as "optimal foraging models"; and the theory that embodies them, "optimal foraging theory." The situations to which optimal foraging theory has been applied, with the exception of a few recent studies, can be divided into the following four categories: (1) choice by an animal of which food types to eat (i.e., optimal diet); (2) choice of which patch type to feed in (i.e., optimal patch choice); (3) optimal allocation of time to different patch...

/pdf/optimal-foraging-a-selective-review-of-theory-and-tests-3ar3ls90ph.pdf

V. S. Ivlev

Papers

Experimental ecology of the feeding of fishes