scholarly journals Polar bears are inefficient predators of seabird eggs

2021 ◽  
Vol 8 (4) ◽  
Author(s):  
Patrick M. Jagielski ◽  
Cody J. Dey ◽  
H. Grant Gilchrist ◽  
Evan S. Richardson ◽  
Oliver P. Love ◽  
...  
Keyword(s):  
Decision Making ◽  
Optimal Foraging ◽  
Visual Cues ◽  
Foraging Ecology ◽  
Optimal Foraging Theory ◽  
Nest Density ◽  
Polar Bears ◽  
Somateria Mollissima ◽  
Resource Density ◽  
Foraging Performance

Climate-mediated sea-ice loss is disrupting the foraging ecology of polar bears ( Ursus maritimus ) across much of their range. As a result, there have been increased reports of polar bears foraging on seabird eggs across parts of their range. Given that polar bears have evolved to hunt seals on ice, they may not be efficient predators of seabird eggs. We investigated polar bears' foraging performance on common eider ( Somateria mollissima ) eggs on Mitivik Island, Nunavut, Canada to test whether bear decision-making heuristics are consistent with expectations of optimal foraging theory. Using aerial-drones, we recorded multiple foraging bouts over 11 days, and found that as clutches were depleted to completion, bears did not exhibit foraging behaviours matched to resource density. As the season progressed, bears visited fewer nests overall, but marginally increased their visitation to nests that were already empty. Bears did not display different movement modes related to nest density, but became less selective in their choice of clutches to consume. Lastly, bears that capitalized on visual cues of flushing eider hens significantly increased the number of clutches they consumed; however, they did not use this strategy consistently or universally. The foraging behaviours exhibited by polar bears in this study suggest they are inefficient predators of seabird eggs, particularly in the context of matching behaviours to resource density.

Choice, optimal foraging, and the delay-reduction hypothesis

1985 ◽  
Vol 8 (2) ◽  
pp. 315-330 ◽  
Author(s):  
Edmund Fantino ◽  
Nureya Abarca
Keyword(s):  
Decision Making ◽  
Operant Conditioning ◽  
Optimal Foraging ◽  
Interdisciplinary Approach ◽  
Optimal Foraging Theory ◽  
Food Presentation ◽  
Food Sources ◽  
Delay Reduction ◽  
Closed Economies ◽  
Potential Food

AbstractBehaving organisms are continually choosing. Recently the theoretical and empirical study of decision making by behavioral ecologists and experimental psychologists have converged in the area of foraging, particularly food acquisition. This convergence has raised the interdisciplinary question of whether principles that have emerged from the study of decision making in the operant conditioning laboratory are consistent with decision making in naturally occurring foraging. One such principle, the “parameter-free delay-reduction hypothesis, ” developed in studies of choice in the operant conditioning laboratory, states that the effectiveness of a stimulus as a reinforcer may be predicted most accurately by calculating the decrease in time to food presentation correlated with the onset of the stimulus, relative to the length of time to food presentation measured from the onset of the preceding stimulus. Since foraging involves choice, the delay-reduction hypothesis may be extended to predict aspects of foraging. We discuss the strategy of assessing parameters of foraging with operant laboratory analogues to foraging. We then compare the predictions of the delay-reduction hypothesis with those of optimal foraging theory, developed by behavioral ecologists, showing that, with two exceptions, the two positions make comparable predictions. The delay-reduction hypothesis is also compared to several contemporary pscyhological accounts of choice. Results from several of our experiments with pigeons, designed as operant conditioning simulations of foraging, have shown the following: The more time subjects spend searching for or traveling between potential food sources, the less selective they become, that is, the more likely they are to accept the less preferred outcome; increasing time spent procuring (“handling”) food increases selectivity; how often the preferred outcome is available has a greater effect on choice then how often the less preferred outcome is available; subjects maximize reinforcement whether it is the rate, amount, or probability of reinforcement that is varied; there are no significant differences between subjects performing under different types of deprivation (open vs. closed economies). These results are all consistent with the delay-reduction hypothesis. Moreover, they suggest that the technology of the operant conditioning laboratory may have fruitful application in the study of foraging, and, in doing so, they underscore the importance of an interdisciplinary approach to behavior.

scholarly journals Individual differences in novelty-seeking are associated with different patterns of preference in a risk-sensitivity procedure in rats

2015 ◽  
Vol 28 ◽  
Author(s):  
Héctor Octavio Camarena Pérez ◽  
Oscar García-Leal
Keyword(s):  
Decision Making ◽  
Individual Differences ◽  
Optimal Foraging ◽  
Optimal Foraging Theory ◽  
Food Delivery ◽  
Choice Situation ◽  
Risk Sensitivity ◽  
Novelty Seeking ◽  
Budget Model ◽  
Human Decision

The preferences of organisms faced with changing conditions in food delivery situations have been studied under the rubric of risk-sensitivity. Optimal foraging theory often applies the energy budget model to explain the preferences shown by organisms, but in this paper we suggest a different approach, one based on the study of individual differences. A sample of rats was classified as high and low novelty-seeking. Afterwards, they were maintained at 75% or 90% of their body weight and exposed to a risk-sensitivity procedure. The results show that the novelty-seeking model is associated with different patterns of preference under a risk-sensitivity procedure, but that these patterns do not correlate with the level of food deprivation employed. Furthermore, we found that the spontaneous alternation between options in a choice situation correlates with the organism’s preference during a risk procedure. Considering recent findings in the area of animal and human decision-making, our results are explained in terms of altered behavioral processes.

Generalizing foraging theory for analysis and design

2011 ◽  
Vol 30 (5) ◽  
pp. 505-523 ◽  
Author(s):  
Theodore P Pavlic ◽  
Kevin M Passino
Keyword(s):  
Decision Making ◽  
Optimal Foraging ◽  
Optimal Foraging Theory ◽  
Foraging Theory ◽  
Random Environments ◽  
Modeling Framework ◽  
Analysis And Design ◽  
Wide Range ◽  
New Models ◽  
Task Processing

Foraging theory has been the inspiration for several decision-making algorithms for task-processing agents facing random environments. As nature selects for foraging behaviors that maximize lifetime calorie gain or minimize starvation probability, engineering designs are favored that maximize returned value (e.g. profit) or minimize the probability of not reaching performance targets. Prior foraging-inspired designs are direct applications of classical optimal foraging theory (OFT). Here, we describe a generalized optimization framework that encompasses the classical OFT model, a popular competitor, and several new models introduced here that are better suited for some task-processing applications in engineering. These new models merge features of rate maximization, efficiency maximization, and risk-sensitive foraging while not sacrificing the intuitive character of classical OFT. However, the central contributions of this paper are analytical and graphical methods for designing decision-making algorithms guaranteed to be optimal within the framework. Thus, we provide a general modeling framework for solitary agent behavior, several new and classic examples that apply to it, and generic methods for design and analysis of optimal task-processing behaviors that fit within the framework. Our results extend the key mathematical features of optimal foraging theory to a wide range of other optimization objectives in biological, anthropological, and technological contexts.

scholarly journals Be different to be better: the effect of personality on optimal foraging with incomplete knowledge

2021 ◽  
Author(s):  
Poppy M. Jeffries ◽  
Samantha C. Patrick ◽  
Jonathan R. Potts
Keyword(s):  
Optimal Foraging ◽  
Optimal Foraging Theory ◽  
Foraging Strategy ◽  
Foraging Strategies ◽  
Partial Knowledge ◽  
Marginal Value ◽  
Animal Populations ◽  
Plausible Mechanism ◽  
Insight Into ◽  
Modelling Approach

AbstractMany animal populations include a diversity of personalities, and these personalities are often linked to foraging strategy. However, it is not always clear why populations should evolve to have this diversity. Indeed, optimal foraging theory typically seeks out a single optimal strategy for individuals in a population. So why do we, in fact, see a variety of strategies existing in a single population? Here, we aim to provide insight into this conundrum by modelling the particular case of foraging seabirds, that forage on patchy prey. These seabirds have only partial knowledge of their environment: they do not know exactly where the next patch will emerge, but they may have some understanding of which locations are more likely to lead to patch emergence than others. Many existing optimal foraging studies assume either complete knowledge (e.g. Marginal Value Theorem) or no knowledge (e.g. Lévy Flight Hypothesis), but here we construct a new modelling approach which incorporates partial knowledge. In our model, different foraging strategies are favoured by different birds along the bold-shy personality continuum, so we can assess the optimality of a personality type. We show that it is optimal to be shy (resp. bold) when living in a population of bold (resp. shy) birds. This observation gives a plausible mechanism behind the emergence of diverse personalities. We also show that environmental degradation is likely to favour shyer birds and cause a decrease in diversity of personality over time.

Optimal foraging: theory and experiment

Nature ◽  
1977 ◽  
Vol 268 (5621) ◽  
pp. 583-584 ◽  
Author(s):  
John Krebs
Keyword(s):  
Optimal Foraging ◽  
Optimal Foraging Theory ◽  
Foraging Theory ◽  
Theory And Experiment
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