Optimal Bayesian foraging policies and prey population dynamics  Some comments on RodriguezGirones and Vasquez
(2000) In Theoretical Population Biology 57(4). p.369375 Abstract
 In this paper we show the densitydependent harvest rates of optimal Bayesian foragers exploiting prey occurring with clumped spatial distribution. RodriguezGirones and Vasquez (1997) recently treated the issue, but they used a patchleaving rule (current value assessment rule) that is not optimal for the case described here. An optimal Bayesian forager exploiting prey whose distribution follows the negative binomial distribution should leave a patch when the potential land not instantaneous) gain rate in that patch equals the best longterm gain rate in the environment (potential value assessment rule). It follows that the instantaneous gain rate at which the patches are abandoned is an increasing function of the time spent searching in... (More)
 In this paper we show the densitydependent harvest rates of optimal Bayesian foragers exploiting prey occurring with clumped spatial distribution. RodriguezGirones and Vasquez (1997) recently treated the issue, but they used a patchleaving rule (current value assessment rule) that is not optimal for the case described here. An optimal Bayesian forager exploiting prey whose distribution follows the negative binomial distribution should leave a patch when the potential land not instantaneous) gain rate in that patch equals the best longterm gain rate in the environment (potential value assessment rule). It follows that the instantaneous gain rate at which the patches are abandoned is an increasing function of the time spent searching in the patch. It also follows that the proportion of prey harvested in a patch is an increasing sigmoidal function of the number of prey initially present. In this paper we vary several parameters of the model to evaluate the effects on the forager's intake rate, the proportion of prey harvested per patch, and the prey's average mortality rate in the environment. In each case, we study an intake rate maximizing forager's optimal response to the parameter changes. For the potential value assessment rule we find that at a higher average prey density in the environment, a lower proportion of the prey is taken in a patch with a given initial prey density. The proportion of prey taken in a patch of a given prey density also decreases when the variance of the prey density distribution is increased and if the travel time between patches is reduced. We also evaluate the effect of using predation minimization, rather than rate maximization, as the currency. Then a higher proportion of the prey is taken for each given initial prey density. This is related to the assumption that traveling between patches is the most risky activity. Compared to the optimal potential value assessment rule, the current value assessment rule performs worse, in terms of longterm intake rate achieved. The difference in performance is amplified when prey density is high or highly aggregated. These results pertain to the foraging patch spatial scale and may have consequences for the spatial distribution of prey in the environment, (C) 2000 Academic Press. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/record/145987
 author
 Olsson, Ola ^{LU} and Holmgren, N M A
 organization
 publishing date
 2000
 type
 Contribution to journal
 publication status
 published
 subject
 in
 Theoretical Population Biology
 volume
 57
 issue
 4
 pages
 369  375
 publisher
 Academic Press
 external identifiers

 scopus:0033877025
 ISSN
 10960325
 DOI
 10.1006/tpbi.2000.1466
 language
 English
 LU publication?
 yes
 id
 60f70b740bf34575933439885ea5b541 (old id 145987)
 date added to LUP
 20070626 11:02:06
 date last changed
 20170101 06:46:19
@article{60f70b740bf34575933439885ea5b541, abstract = {In this paper we show the densitydependent harvest rates of optimal Bayesian foragers exploiting prey occurring with clumped spatial distribution. RodriguezGirones and Vasquez (1997) recently treated the issue, but they used a patchleaving rule (current value assessment rule) that is not optimal for the case described here. An optimal Bayesian forager exploiting prey whose distribution follows the negative binomial distribution should leave a patch when the potential land not instantaneous) gain rate in that patch equals the best longterm gain rate in the environment (potential value assessment rule). It follows that the instantaneous gain rate at which the patches are abandoned is an increasing function of the time spent searching in the patch. It also follows that the proportion of prey harvested in a patch is an increasing sigmoidal function of the number of prey initially present. In this paper we vary several parameters of the model to evaluate the effects on the forager's intake rate, the proportion of prey harvested per patch, and the prey's average mortality rate in the environment. In each case, we study an intake rate maximizing forager's optimal response to the parameter changes. For the potential value assessment rule we find that at a higher average prey density in the environment, a lower proportion of the prey is taken in a patch with a given initial prey density. The proportion of prey taken in a patch of a given prey density also decreases when the variance of the prey density distribution is increased and if the travel time between patches is reduced. We also evaluate the effect of using predation minimization, rather than rate maximization, as the currency. Then a higher proportion of the prey is taken for each given initial prey density. This is related to the assumption that traveling between patches is the most risky activity. Compared to the optimal potential value assessment rule, the current value assessment rule performs worse, in terms of longterm intake rate achieved. The difference in performance is amplified when prey density is high or highly aggregated. These results pertain to the foraging patch spatial scale and may have consequences for the spatial distribution of prey in the environment, (C) 2000 Academic Press.}, author = {Olsson, Ola and Holmgren, N M A}, issn = {10960325}, language = {eng}, number = {4}, pages = {369375}, publisher = {Academic Press}, series = {Theoretical Population Biology}, title = {Optimal Bayesian foraging policies and prey population dynamics  Some comments on RodriguezGirones and Vasquez}, url = {http://dx.doi.org/10.1006/tpbi.2000.1466}, volume = {57}, year = {2000}, }