Original Research Article How spatial resource distribution and memory impact foraging success: A hybrid model and mechanistic index § Christian Ernest Vincenot a, *, Stefano Mazzoleni b , Kazuyuki Moriya a , Fabrizio Cartenı ` b , Francesco Giannino b a Department of Social Informatics, Graduate School of Informatics, Kyoto University, Japan b Dipartimento di Agraria, Universita’ degli Studi di Napoli Federico II, via Universita’ 100, Portici 80055, NA, Italy 1. Introduction Foraging is one of the primary activities supporting life and it is critical for the survival of any animal. Its study has been an active field of research in behavioral ecology since the very beginning of this discipline (MacArthur and Pianka, 1966). With the formaliza- tion of increasingly complex foraging theories, mathematic modeling and then computerized dynamic simulations have become important scientific tools to investigate this topic. Initially, foraging models were limited to finding the strategy optimizing energy intake over short time periods (Stephens and Krebs, 1986), and this trend has survived until nowadays (Be ´ nichou et al., 2005; Moen et al., 1997; Oshanin et al., 2009). Soon, the need for an increased accuracy in the representation of processes became obvious. Among others, it was early recognized that spatially implicit modeling may be insufficient to capture certain aspects of foraging (Pyke, 1983; Roese et al., 1991; Turner et al., 1995). Some traditional models also wrongfully treated metabolism as a mechanism not directly impacting foraging activities (Moen et al., 1997). Furthermore, many studies assumed that the forager is omniscient about its environment, and have thereby neglected the importance of information acquisition and learning (Bernstein et al., 1988; Dall et al., 2005; Eliassen et al., 2007). Within the last two decades, these assumptions have been tackled separately by numerous studies. For instance, some have Ecological Complexity 22 (2015) 139–151 A R T I C L E I N F O Article history: Received 25 August 2014 Received in revised form 29 March 2015 Accepted 31 March 2015 Available online 24 April 2015 Keywords: Spatially explicit Bioenergetics System dynamics Individual-based Random walk Metric A B S T R A C T Understanding how animals forage has always been a fundamental issue in Ethology and has become critical more recently in Environmental Conservation. Since the formalization of optimal foraging theory, theoretical models intended to depict the behavior of a generic forager have served as the main tools to analyze and ultimately comprehend the mechanisms of foraging. Due to complexity and technical constraints, these models have traditionally focused on single aspects of foraging, leaving out other concurrent processes that may also interplay. The recent inclusion of several facets inside united models has given rise to interesting results on the importance of interacting factors such as memory and resource heterogeneity. In this paper, we present a hybrid model integrating metabolism, foraging decisions, memory, as well as spatially explicit movement and resource distribution. We use it to examine the effects of spatial resource distribution – an aspect often neglected in favor of probabilistic resource heterogeneity – on the viability of a generic random-walking forager, and rely on the model to devise an ecological metric that can explain and render the relative profitability of given spatial distributions. Furthermore, we assess the significance of memory properties relatively to the profitability of resource distributions. Most notably, we reveal contrasted effects of memory depending on the aspect of resource varied in space (i.e. prey abundance, or prey body mass). On the whole, a general comparison of our findings with results obtained with spatially implicit models leads us to stress the complex interaction between memory and spatial resource distribution as well as the criticality of spatial representation in the modeling of foraging. Accordingly, we conclude with a discussion on the ecological implications of these results, as well as the advantages of hybrid modeling for the accurate simulation of foraging. ß 2015 Elsevier B.V. All rights reserved. § Note: For demonstration purpose, a simplified version of the model presented in this paper is available online at the following address: http://christian.vincenot.biz/ models.html. * Corresponding author at: Yoshida Honmachi, Sakyo-ku, Kyoto 606-8501, Japan. Tel.: +81 75 753 3132; fax: +81 75 753 3133. E-mail address: Christian@Vincenot.biz (C.E. Vincenot). Contents lists available at ScienceDirect Ecological Complexity jo ur n al ho mep ag e: www .elsevier .c om /lo cate/ec o co m http://dx.doi.org/10.1016/j.ecocom.2015.03.004 1476-945X/ß 2015 Elsevier B.V. All rights reserved.