Seed choice by rodents: learning or inheritance?
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Learning plays a central role in animal life, and it has received special attention in the context of foraging. In this study, we have tested whether learning operates in seed choices by rodents using the Algerian mouse (Mus spretus) and Holm oak (Quercus ilex) acorns as a model. At the laboratory, those rodents captured in the field during the acorn fall period (experienced individuals) rejected weevil-infested acorns, presumably because of their lower energetic value. By contrast, rodents born in captivity and reared without any contact with acorns (naïves) predated weevil-infested acorns at similar rates than sound ones. After exposing naïves to infested and sound acorns during 15 days, they rejected infested acorns as the experienced individuals. In the field, predation on weevil-infested acorns was lower than on sound ones. Predation rates on infested acorns were lowest at the end of the acorn fall season, whereas predation rates of sound acorns increased along the same period. This might be explained by the improved ability to reject infested acorns because of the accumulated experience acquired by the initially naïve rodents along the acorn fall season. We show that learning shapes strongly seed choices by rodents, and it may be advantageous over inherited behaviors in variable unpredictable situations, such as acorn infestation rates that vary strongly between years and trees. We consider that the role of learning has to be taken into account in future studies on seed predation by rodents.
KeywordsAcorns Learning Rodents Seed predation Weevils
We thank B. Nicolau for his assistance in the field and laboratory. M. Díaz, JM Aparicio, T Czeschlik, and three anonymous reviewers provided helpful comments on the manuscript. AM and RB were supported by a fellowship from La Junta de Comunidades de Castilla-La Mancha. This study was supported by the projects REN2003-07048/GLO, CGL2006-06647/BOS, PAC-02-008, 096/2002 and 003/2007. Rodents were captured and maintained in the laboratory under license from the JCCM.
- Blanco JC (1998) Mamíferos de España, vol. II. Editorial Planeta S. A., BarcelonaGoogle Scholar
- Bonal R, Muñoz A (2008) Seed growth suppression constrains the growth of seed parasites: premature acorn abscission reduces Curculio elephas larval size. Ecol Entomol (in press)Google Scholar
- Dukas R (1998) Cognitive ecology. University of Chicago Press, ChicagoGoogle Scholar
- Galef BJ Jr (1996) Social enhancement of food preferences in Norway rats: a brief review. In: Heyes CM, Galef BJ Jr (eds) Social learning and imitation: the roots of culture. Academic, New York, pp 49–64Google Scholar
- García D, Gomez JM, Zamora R, Hodar JA (2000) Do empty Juniperus communis seeds defend filled seeds against predation by Apodemus sylvaticus? Ecoscience 7:214–221Google Scholar
- Jansen PA, Bartholomeus M, Bongers F, Elzinga JA, den Ouden J, Van Wieren SE (2002) The role of seed size in dispersal by a scatter-hoarding rodent. In: Levey DJ, Silva WR, Galetti M (eds) Seed dispersal and frugivory: ecology, evolution and conservation. CAB International, Wallingford, pp 209–225Google Scholar
- Jenkins SH (1997) Perspectives on individual variation in mammals. J Mammal 78:271–273Google Scholar
- Muñoz A (2005) Ecological analyses of the predator and dispersal behaviour of Algerian mice (Mus spretus) and wood mice (Apodemus sylvaticus) foraging on Holm oak (Quercus ilex) acorns. Ph.D. thesis, Universidad Complutense de Madrid, SpainGoogle Scholar
- Shettleworth SJ (1998) Cognition, evolution, and behavior. Oxford University Press, New YorkGoogle Scholar
- Stephens DW, Krebs JR (1986) Foraging theory. Princeton University Press, Princeton, NJGoogle Scholar
- Vander Wall SB (1990) Food hoarding in animals. University of Chicago Press, ChicagoGoogle Scholar