Study On Selection And Recovery Of Cache Sites By Siberian Chipmunks, Tamias Sibiricus

Scattered-hoarding sites can be recovered by scattered-hoarding animals withtheir eyes, olfactory and spatial memory. It is still unclear how they use those toestablish their scattered-hoarding caches? We chose Siberian chipmunks (Tamiassibiricus) as experimental animals and conducted a series of behavioural experimentsin the semi-natural/home-in enclosures as well as in the field, in an attempt to revealthe mechanisms of directional selection and recovery of scatterhoards by this animal.The results we found are following:(1)In the semi-natural enclosures. The larger visual markers can significantlyaffect the scattered-hoarding behavior of Siberian chipmunks. Moreover, the largervisual markers significant influenced the distribution of scattered hoarding caches ofSiberian chipmunks. Siberian chipmunks tended to cache the seeds to the sites clearlymarked by visual objects. However, the smaller markers showed less effect. And theeffect of visual markers on hoarding behavior of different gender chipmunks wasdifferent. Significant influence of visual markers was found on scattered-hoardingbehavior of male scatterhoarders, but the less influence on female.(2)Our study showed that there was no effect of exogenous scents on the selectionof scatterhoards by Siberian chipmunks. The odors of Agastacher ugosa, Artemisiaprinceps and Cominumcyminum L. did not influence caching behavior of T. sibiricus.The scattered-hoarding behavior of Siberian chipmunks may be more likely to beinfluenced by the seed’s own odors.(3)There was significant impact of water content in soil on the directionalselection for scattered cache sites by Siberian chipmunks. The moisture levels in theenvironments had a significant impact on scattered-hoarding behavior of Siberianchipmunks. In the semi-natural enclosures, Siberian chipmunks preferred to bury moreseeds in the soil with moderate moisture content, which is expected to reduce and evenavoid cache losses. It showed that, in the field, the average water content of caches of Siberian chipmunks was higher than the overall soil samples in the mixed oak-pinforests. On the one hand, moderate moisture content in soil is believed to not only helpSiberian chipmunks find themselves scatterhoards, but also prevent cache loss by otherthieves. On the other hand, it’s is advantageous for germination and growth of cachedseeds under moderate moisture environments, provided they successfully escapepredation by food hoarding animals.(4)In the semi-natural enclosures, Siberian chipmunks showed a precisely spatialmemory to retrieve their own scatterhoards. The artificial caches paired with those ofchipmunks were recovered quickly, while the caches of chipmunks were more likely tobe reserved. In the field, however, Siberian chipmunks tended to recover their ownscatterhoards more quickly than the thieves with their spatial memory. We suggest thatthis is a sophisticated food-hoarding strategy which based on stronger spatial memoryto scatterhoards.(5)Our study in the home-in enclosures showed that Siberian chipmunks removedmore shallow caches than deep ones. Recovery rates increased with the cache sizes.Higher soil water content of caches facilitated Siberian chipmunks to locate the buriedseeds. We predicted that there may be a significant effect of the chemical odor of seedsconnected with the olfactory of Siberian chipmunks.