Abstract
Selecting seeds for long-term storage is a key factor for food hoarding animals. Siberian chipmunks (Tamias sibiricus) remove the pericarp and scatter hoard sound acorns of Quercus mongolica over those that are insect-infested to maximize returns from caches. We have no knowledge of whether these chipmunks remove the pericarp from acorns of other species of oaks and if this behavior benefits seedling establishment. In this study, we tested whether Siberian chipmunks engage in this behavior with acorns of three other Chinese oak species, Q. variabilis, Q. aliena and Q. serrata var. brevipetiolata, and how the dispersal and germination of these acorns are affected. Our results show that when chipmunks were provided with sound and infested acorns of Quercus variabilis, Q. aliena and Q. serrata var. brevipetiolata, the two types were equally harvested and dispersed. This preference suggests that Siberian chipmunks are incapable of distinguishing between sound and insect-infested acorns. However, Siberian chipmunks removed the pericarp from acorns of these three oak species prior to dispersing and caching them. Consequently, significantly more sound acorns were scatter hoarded and more infested acorns were immediately consumed. Additionally, indoor germination experiments showed that pericarp removal by chipmunks promoted acorn germination while artificial removal showed no significant effect. Our results show that pericarp removal allows Siberian chipmunks to effectively discriminate against insect-infested acorns and may represent an adaptive behavior for cache management. Because of the germination patterns of pericarp-removed acorns, we argue that the foraging behavior of Siberian chipmunks could have potential impacts on the dispersal and germination of acorns from various oak species.
Highlights
Seed dispersal is an important ecological process that influences plant regeneration, community composition, and ecosystem diversity [1,2,3,4]
These results suggest that Siberian chipmunks do not preferentially select sound acorns from the seed stations when presented with both infested and sound seeds
The infested acorns were more likely to be eaten at seed stations (EIS) than the sound acorns (Q. variabilis: F = 5.653, df = 1, P = 0.032; Q. aliena: F = 43.525, df = 1, P,0.001; Q. serrata var. brevipetiolata: F = 8.182, df = 1, P = 0.013) (Figure 1)
Summary
Seed dispersal is an important ecological process that influences plant regeneration, community composition, and ecosystem diversity [1,2,3,4]. A large proportion of seeds are eaten and killed by seed consuming animals, some are cached and may eventually escape predation and result in seedling establishment if the seeds are not recovered [1,11,12,13]. Seed perishability by insects cause substantial losses to caches; a variety of behavioral adaptations of rodents exist for maximizing returns from cached seeds [16,17,19,20]. Many studies show that seed hoarding animals prefer intact non-infested seeds over those infested by insects [20,21,22,23,24,25,26], reflecting their ability to distinguish between the two types. Other studies show that rodents are incapable of discriminating against infested seeds [27,28,29,30]
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