Effects Of Inter-specific Pilferage Risk On Hoarding Behavior Of Rodents In Donglingshan Area

Food-hoarding is an important strategy adopt by some animals to cope 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. There are two basic food-hoarding patterns:larder-hoarding and scatter-hoarding. 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, whereby one species can pilfer foods from the other species, but it hardly happens in reverse. Hoarders have to adopt a series of behavioral strategies to reduce food loss and prevent pilferage posted again by interspecific individuals.Large field mice (Apodemus peninsulae LFM) and Chinese white-bellied rats (Niviventer confucianus CWR) are dominant rodent species in Donglingshan area, sharing similar habitats of forests and shrulands and food items of plant seeds. They are common seed consumers and dispersers of trees. LFM are both larder hoarder and scatter hoarder, whereas CWR are only larder hoarder. Our previous studies indicate that pilferage between LFM and CWR is asymmetrical, whereby CWR are capable of pilfering caches scatter-hoarded by LFM, but LFM are unable to steal seeds larder-hoarded by CWR. However, we knew little about how do LFM in inferior position response to the pilferage pressure from CWR, an in reverse.In this study, we conducted a series experiments in semi-natural enclosures to explore pilferage between LFM and CWR. Through artificial pilferage to simulate the pilferage pressure posited by animals, we study effects of the pilferage pressure of Chinese white-bellied rat (CWR) on the hoarding behaviors of LFM and in reverse. Our objective was to investigate the relationship between the two rodent species with respect to food hoarding, pilferage and pilferage avoidance, which that were beneficial for explaining their coexistence in the study area.We found that with the pilferage pressure of CWR, LFM regulated their hoarding strategies that:(1), reduced both larder and scatter hoarding efforts; (2), shifted hoarding patterns from scatter hoarding to larder hoarding; (3), LFM discovered part of their scatter-buried seeds and removed them into nest (30.88%); and (4), established new caches in the areas with low pilferage risks. These results suggest that LFM tended to decrease hoarding, transfer from scatter hoarding to larder hoarding, and avoid high pilferage places when hoarding to respond to the pilferage risks posited by CWR, their sympatric food competitors.CWR only larder-hoarded seeds, and their larder hoarded seeds cannot be pilfered by LFM. Their food hoarding pattern and hoarding efforts were not affected by their food competitors of LFM. Furthermore, pilferage pressure of rat-like hamsters (Tscherskia triton) and David’s rock squirrels (Sciurotamias davidianus)had no effects on hoarding behavior of CWR either. These results indicate that other rodent species in the same area had little effects on CWR’s hoarding behaviors.In summary, we found pilferage between LFM and CWR is asymmetrical whereby CWR can steal scatter caches from LFM, but LFM cannot pilfer larder caches from CWR under enclosure conditions. LFM have adopted a lot of strategies to reduce caches loss posited by sympatric pilferers, whereas CWR’s hoarding behaviors were not altered significantly by other sympatric species. These results suggest that pilferage pressure posited by interspecific species have different effects on scatter hoarders and larder hoarders in the field. Differentiation in food-hoarding behavior of rodents is one important factor influencing their coexistence. More studies are needed in the future to look at the effects of strategies of pilferage avoidance on survival and reproduction of species with low social level.