BUSCADOR RECOLECTA

Cache pilferage by competing conspecifics is a very common hoarding behavior used by animals. Members of rodent communities use a wide variety of strategies to minimize this pilferage. In this work, we investigated one of these strategies. We observed that certain rodent species partially consume acorns, leaving the embryo intact. We investigated whether this strategy was used by Mus spretus Lataste 1883 (Algerian mouse) to avoid cache pilferage by competing conspecifics. Partially consumed acorn remains left in underground stores could be viewed as remains by competing conspecifics, and would therefore be rejected, preventing its consumption and pilferage. To test our hypothesis, we designed three experiments on the preference for intact acorns, acorns that had been partially consumed by the rodent itself or the remains from other competing conspecific rodents. The study verified whether the remains of partially consumed acorns were rejected. We verified that these remains are more highly valued than intact acorns or even the remains of the rodent’s own previous consumption, thus rejecting our hypothesis. Remains are not used as a strategy to prevent theft. However, preference for the remains of other rodents’ acorns could form part of an anti-theft strategy. If the acorn remains are used as a decoy to attract the attention of thieves to prevent the consumption of intact acorns, the intact acorns would be better preserved in the stores for longer periods of time. The remains were consumed before the intact acorns. We verified that rodents prefer the remains of other rodents’ acorns to their own, and even prefer them to intact acorns. This behavior may be part of a strategy to reduce other rodents’ reserves to avoid future competition by conspecifics.

The relationship between scatter-hoarding rodents and oak species has been considered on a scale from antagonism to mutualism. Depending on the costs and benefits, the outcome of the relationship can be found at one extreme or the other. Costs have included destruction of acorns that occurs during predation, but not all acorns attacked lose their embryos. As representatives of the mutualistic end, we present two species with this behavior (Mus spretus and Apodemus sylvaticus). Representing the antagonistic extreme, we present a predatory species that destroys the embryo (Microtus arvalis). The objective of this study is to test the preferences of both rodent groups for acorns. The results showed that there is one acorn species (Quercus ilex) that is preferred by the three rodent species. This acorn species has high concentrations of nutrients, low concentrations of tannins and thin shell. These characteristics attract the attention of rodents that could carry these acorns. There are two other acorn species (Quercus suber and Quercus rubra) that are consumed with little intensity for having low concentrations of nutrients, high concentration of tannins and thick shell. These characteristics escaping predators although transportation is not guaranteed. These acorns would germinate and emerge under the trees that have produced them and increase intraspecific competition. Coincidence preferences shown by the three rodent species poses a risk for the oak species, since the recent arrival of the predator (antagonist) species in the study area could paralyze the dispersal process carried out by the other two mutualistic species through predation., Departamento de Ciencias Agroforestales