Pilferage And Pilferage Avoidance Behaviors In Sympatric Small Rodents In Donglingshan Area

Food-hoarding is an important strategy adopt by some animals to against with seasonal fluctuations in food availability. Stored food items are beneficial to increase the chances of survival and reproduction of hoarders during the period of food scarcity. Pilferage from intra-and inter-specific individuals is one of the major reasons of cache loss for food-hoarding animals, and pilferage between sympatric species of hoarders is often asymmetrical that one species can pilfer foods from the other species, but it hardly happens in reverse. As such, hoarders have to adopt a series of strategies to prevent pilferage posted by other individuals under different conditions, for example, when their stores are pilfered completely, or when they are in face of dominant pilfers.At here, I subjected three sympatric food-hoarding rodents (the Korean field mouse (KFM), Apodemus peninsulae, both scatter and larder hoarder; Chinese white-bellied rat (CWR), Niviventer confucianus, larder hoarder only; and Pere David’s rock squirrel (DRS), Sciurotamias davidianus, predominantly a scatter hoarder) to repeated episodes of complete cache losses over nine sequential trials in semi-natural enclosures. My objective is to test that the subjects are able to anticipate future outcomes of hoarding and adjust their current behaviors following future outcomes to respond to complete food loss.The CWR and KFM are two dominant sympatric species in our study area with similar diets, habitats and nocturnal activity, but with dissimilar body size (KFM:80-135mm body length,20-35g body mass; CWR:125-195mm body length,45-150g body mass) and hoarding behaviors (CWR is exclusively a larder hoarder, KFM adopt both larder and scatter hoarding). In this project, I also conducted a series of enclosure experiments to investigate the asymmetrical pilferage between KFM and CWR that CWR can, but not too much high in ratio, pilfer scatter-hoarded food from KFM, but KFM cannot pilfer larder-hoarded food from CWR.Following the manipulations of repeated complete food loss,1) all of the three species consistently increased harvest, suggesting enhancement of harvest is an inherent strategy in sympatric rodents in response to food loss;2) The KFC and CWR significantly increased hoarding, while DRS decreased hoarding (but not significantly), rejecting the giving-up hoarding hypothesis that hoarders tend to give up hoarding intensity if their efforts are not rewarded in the future;3) all of the three species consistently increased eating, implying hoarders appear to increase internal (fat) energetic reserves to cope with food loss;4) CWR significantly increased harvest and hoarding immediately while KFC (at trail5) and DRS (at trail3) responded food loss torpidly, suggesting larder hoarders are more concerned about food loss than scatter hoarders and those hoarders adopt both scatter and larder strategies;5) females of KFC are more concerned about food loss than males, but surprisingly it is just the reverse in CWR, and there are not sex differences in DRS, implying sex difference of hoarders in response to food loss may be species-specific and varies with conditions;5) KFC only increased larder hoarding, suggesting larder hoarding strategy is more important than scatter hoarding for food protection in hoarders have both scatter and larder hoarding behaviors. This study firstly reveals the behavioral responses of sympatric hoarders to consistently unrewarded hoarding efforts (repeated complete food loss). The results should be interpreted cautiously and studied further because animals do not appear to suffer from complete food loss repeatedly in the wild, and very few studies have focused on consistently rewarded hoarding. However, our findings still might be used as valuable sources of reference to well understand behavioral adaptations of animals in food protection under violently changed environments.The KFM ate9.4%, re-larder-hoarded4.7%, and re-scatter-hoarded1.2%of their primary scatter-hoarded seeds when CWR were present as pilfers. And3.5%of KFM’s scatter-hoarded seeds were pilfered by CWR. On the contrary, no CWR’s larder-hoarded seeds were pilfered by KFM when KFM were present as pilfers. The CWR rarely discovered caches with＞3.0cm depths and＞50.0cm densities (nearest distance between caches), which are approximately equal to the mean depth and mean density preferred by KFM for hoarding. These results suggest that CWR can pilfer food stores from KFM, but it does not happen in reverse. The KFM compete food sources with CWR by recaching in scatter, eating, and larder hoarding, and they scatter-hoard seeds with a certain depth and a certain density to avoid pilferage from CWR. Behavioral differentiations in hoarding may reduce competition and promote coexistence between these species.