Perspectives in optimal foraging

Krebs, John R.; Stephens, David W.; Sutherland, William J.; Myers, J. P.

doi:10.1017/cbo9780511759994.008

Cited by 279 publications

(135 citation statements)

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“…Although the experiments did not directly address this problem, preferences for specific prey taxa do exist (Fig. 2, Treatment 3), according to those expected from optimal foraging theory (Krebs et al, 1983) or as yet unspecified rules.…”

Section: Resultsmentioning

confidence: 98%

Foraging Behavior and Switching by the Grasshopper Sparrow Ammodramus savannarum Searching for Multiple Prey in a Heterogeneous Environment

Joern¹

1988

American Midland Naturalist

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ABSTRACT:Switching among four alternative grasshopper species by the grasshopper sparrow (Ammodramus savannarum) through frequency-dependent predation was examined. Grasshoppers were presented against a heterogeneous natural background in an outdoor aviary where total density was held constant but relative density of each grasshopper species varied. Switching among prey, primarily between two of the four species, and inter-bird variability in switching was observed. Species-specific preferences and interactions among the alternative grasshopper species affected the final diet choice as one grasshopper species was always preferentially selected and another disregarded independent of changes in relative density. Attributes of avian foraging behavior, including: (a) proportion of total time spent handling prey, searching for prey or engaging in nonforaging activity; (b) capture success; (c) time required to catch prey (relative to either total or search time), and (d) attack distance did not vary according to the relative abundance treatments. Results of this study are related to quantitative estimates of predation and relative densities of grasshopper species in a natural grassland setting.

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Section: Resultsmentioning

confidence: 98%

Foraging Behavior and Switching by the Grasshopper Sparrow Ammodramus savannarum Searching for Multiple Prey in a Heterogeneous Environment

Joern¹

1988

American Midland Naturalist

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“…Whether they swam slow or fast, fish would still encounter all of the food clumps. However, we consider it unlikely that fish are able to distinguish between the energetic implications of clumped food in the field versus clumped food in the laboratory (Clark & Mange1 1.986) Th.erefore, rather than attempting to achieve optimality in foraging under our specific laboratory conditions, we consider it likely that fish were operating under a generalized rule of thumb (Krebs et al 1983) 'swim faster when food is clumped', which would tend to approximate optimality under many natural conditions. Alternatively, swimming faster when food is clumped may have nothing to do with optimality, but may instead result from intragroup competition.…”

Section: Discussionmentioning

confidence: 97%

Altered search speed and growth:social versus independent foraging in two pelagic juvenile fishes

Ryer¹,

Olla²

1997

Mar. Ecol. Prog. Ser.

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ABSTRACT-Prior studies have demonstrated that juvenile walleye pollock Theragra cl?alcogramma forage socially in schools for spatially and temporally clumped food, but forage more independently for spatially and temporally dispersed food. One advantage of social foraging is that fish in schools may be able to locate more food clumps than fish foraging individually. However, data also indicate that walleye pollock swim faster when foraging socially. CVe conducted laboratory experiments to evaluate the effect of food distribution upon the energetic foraglng costs lncurred by juvenile walleye pollock and sablefish Anaplopoma fimbna. We predicted that when given identical rations, fish receiving clumped food would swim faster, expending more energy, and therefore grow more slowly than fish receiving dispersed food After 2 wk under these 2 foraging regimes, juvenile walleye pollock receiving clumped food swam 50% faster, but experienced 19% lower growth, than walleye pollock receiving dispersed food. Sablefish demonstrated only a weak swim speed response, with no difference in growth between food distributions. Our results demonstrate that although social foraging may increase encounter rates with food, in some specles there may also be an energetic cost for this behavior, which will have a n influence upon energet~c efficiency, potentially affecting growth and survival.

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“…Empirical evidence from a wide range of studies with different animals indicates that this foraging "currency" can in fact explain many observations (see reviews in Krebs et al 1983;Stephens and Krebs 1986). Only in a few cases, however, have predictions from alternative currencies been compared at the same time.…”

Section: About Some Concepts For Further Researchmentioning

confidence: 99%

Invitation Paper (C.P. Alexander Fund): Foraging of Individual Workers in Relation to Colony State in the Social Hymenoptera

Schmid‐Hempel¹,

Winston

Ydenberg

1993

Can Entomol

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The Canadian Entomolo~isr 125: 12%160 (1993) Workers of social insects are members of colonies that survive and reproduce together. Therefore, the behavioral activities of individual workers should be integrated with colony state. We here summarize and discuss the relationship between colony state and foraging behavior of individual workers under the provisional assumption that the colony is a unit. We argue that colony state can be described by a number of variables that should relate to fitness components in order to be meaningful. Among the possible candidates, colony population size seems to have an overriding importance in many respects, as shown by its relation to fitness components such as survival probability and reproductive performance. Other important variables include colony demography, i.e. caste or size distributions, nutritional status, or queen number. Each of these variables has been shown to affect fitness components; however, the evidence is rather scanty. We also discuss the evidence that variation in colony state variables relates to variation in individual worker behavior. Nutritional status (i.e. low or high levels of food stores) and colony size have been shown repeatedly to affect individual behavior. However, most of the evidence comes from the honey bee. Some studies suggest that behavioral responses are hierarchically structured. More work needs to be done to investigate the actual mechanisms of integration of individual behavior with colony state. Some knowledge has accumulated about the processes that govern recruitment to food sources. We conclude this review by discussing some concepts and problems for further research. These include the concept of a preferred colony state to which the colony should return after disturbance through the behavioral activities of the workers. Further theoretical elaboration and empirical investigations may help to elucidate whether this concept is useful and necessary. A largely neglected issue concerns the number versus effort problem, i.e. whether individuals should work harder or more workers should be allocated to a task that is in demand. We propose a simple scenario that suggests testable predictions. Finally, we discuss how colony state, individual work load, and the dependence of worker mortality rate on activity level may interact to generate different short-term foraging strategies that workers should adopt. ResumeChez les insectes sociaux, les ouvrikres appartiennent i une colonie ou la survie et la reproduction sont des phknombnes collectifs. Les activitks comportementales de chacune des ouvribres font donc partie intkgrante de l'ktat de la colonie. La relation entre I'ktat de la colonie et le comportement de qu&te de nourriture d'ouvrikres particulikres est dkfinie et examinee dans le cadre de l'hypothkse selon laquelle la colonie fonctionne comme une unitk. Nous croyons que I'ktat de la colonie peut &tre dkcrit par un certain nombre de variables qui n'ont de sens que si elles sont relikes aux composantes du "fitness." Parmi l...

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Perspectives in optimal foraging

Cited by 279 publications

References 0 publications

Foraging Behavior and Switching by the Grasshopper Sparrow Ammodramus savannarum Searching for Multiple Prey in a Heterogeneous Environment

Foraging Behavior and Switching by the Grasshopper Sparrow Ammodramus savannarum Searching for Multiple Prey in a Heterogeneous Environment

Altered search speed and growth:social versus independent foraging in two pelagic juvenile fishes

Invitation Paper (C.P. Alexander Fund): Foraging of Individual Workers in Relation to Colony State in the Social Hymenoptera

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