Evidence of high individual variability in seed management by scatter-hoarding rodents: does ‘personality’ matter?

Abstract

The predation and dispersal of seeds by scatter-hoarding animals is one of the most studied processes in the context of animal-plant interactions. The seed management by these animals has been traditionally approached at the population level, assuming that the patterns documented in field are similar among all individuals of the population, and considering the variability within the population as random noise. However, little is known about to what extent this variability responds to different and consistent behavioural displays among individuals. The aim of this study was to analyse the individual variation and consistency in behaviour by scatter-hoarding rodents within a population. As model we used the wood mouse (Apodemus sylvaticus), a key disperser of holm oak acorns (Quercus ilex) that, in turn, suffers a high predation pressure by the common genet (Genetta genetta). In two sets of laboratory experiments, we compared the variance and consistency in behavioural displays and acorn managing generated by the individual differences with that generated by the manipulation of the perceived predation risk using scents of genets. Genet scents reduced the activity (i.e. time out of the refuge) in all rodents, but the differences and the consistency in activity among individuals accounted for the 82.5% of total variance. Also, rodents showed different and consistent displays of stressed or relaxed behaviours. More than 87% of variance in seed managing variables, like dispersal distance and seed size selection, was explained by consistent differences among individuals across scent treatments. The increase of stressed behaviours and decrease of relaxed ones were positively related with the dispersal ability (i.e. longer distances and larger acorns). Our study highlights the importance of considering the individual component of behaviour in scatter-hoarding rodents. This fine-scale level, largely overlooked in the ecological framework, will help to increase our understanding on seed management by scatterhoarding animals.

Estimating the long-term repeatability of food-hoarding behaviours in an avian predator

“…We here provide, to our best knowledge, the first repeatability estimates of food-hoarding behaviours in the wild. These are lower than previously reported repeatability estimates for larder-hoarding propensity in kangaroo rats [54] and seed management patterns in scatter-hoarding wood mice [55], although these studies were performed in captivity and over shorter timescales. In our study population, spatial variations in habitat composition likely influence the abundance of the different prey groups and could explain some of the among-individual variance in food store composition.…”

Ungulate presence and predation risks reduce acorn predation by mice in dehesas

“…Consequently, predation rates were reduced and larger acorns had a higher probability of survival. In principle, these results suggest that intermediate levels of stress can enhance the probability of acorn dispersal by rodents (as suggested by [ 59 ]). Nonetheless, a high proportion of acorns were deposited within resprouts growing under tree canopies, where the establishment of a new seedlings is highly unlikely [ 60 ].…”

Biological integrity enhances the qualitative effectiveness of conditional mice-oak mutualisms

“…In dehesas, the pervasiveness of open land cover forces mice to concentrate their activities beneath canopies [13,24,56], and decreases the likelihood that mobilized acorns are encountered and consumed [58]. Taken together, our results suggest that intermediate levels of stress can enhance seed dispersal effectiveness by mice (as suggested by [52,59]). Accordingly, in our simulations, suboptimal conditions (due to increased risks or ungulate presence) enhanced dispersal.…”