Abstract

Understanding rodent seed caching behavior is critical for effective forest management and conservation. While it is well established that rodent feeding behavior is strongly affected by seed traits and insect infestation of seeds, there is still a knowledge gap on how these factors affect rodent feeding behavior. Here we conducted a series of experiments to investigate the feeding and hoarding preferences of two sympatric rodent species, the Chinese white-bellied rat (Niviventer confucianus) and South China field mouse (Apodemus draco) in response to Chinese chestnuts (Castanea mollissima) of contrasting seed size and insect infestation. When only sound nuts (not infested nuts) were provided, both species preferentially consumed larger nuts, esp. the larger N. confucianus showed more pronounced selective preference for larger nuts than the smaller A. draco. When sound and insect-infested nuts of equal size were provided, neither species selected for sound over insect-infested nuts, but infested seeds were more frequently consumed in situ. If nuts of differing size and infestation status were provided, rodents preferred to eat and hoard larger seeds regardless of insect infestation. Overall, however, infested seeds were more often consumed immediately in situ while sound seeds were more often consumed ex situ or cached. Our results thus support the seed size hypothesis, but show little evidence for the insect infestation hypothesis, and highlight that food preferences and optimal foraging decisions differ between sympatric rodent species.

Significance statement

Rodent caching and feeding behaviors are strongly affected by co-varying seed traits such as size and insect infestation, which in turn regulate seed survival and seedling recruitment. By using semi-natural enclosures, we detected differences in feeding and hoarding behaviors between sympatric rodent species, and their different preferences for seed size and insect infestation. These different preferences may support the seed size hypothesis. Rodents based their foraging decision predominantly on seed size and not insect infestation, preferring to eat and hoard larger seeds regardless of their insect infestation. We suggest that the differences in feeding and hoarding behaviors of sympatric rodent species in relation to seed size and insect infestation should be considered in future field studies, as this will help us to better understand mechanisms that impact forest management and conservation.