Effects of interspecific competition on food hoarding and pilferage in two sympatric rodents

Abstract

Food hoarding and pilferage in rodents may be regulated by intense competition between sympatric species that have similar habitats, diets and activity, but studies exploring this remain rare. Here, we used semi-natural enclosures to investigate food-hoarding and cache pilferage interactions between sympatric Korean field mice (KFM) (Apodemus peninsulae) and Chinese white-bellied rats (CWR) (Niviventer confucianus). KFM and CWR have similar diets, habitat and nocturnal activity, but the smaller KFM larder and scatter hoards and larger CWR larder hoard only. We found that KFM harvest, larder-hoard and eat seeds at a greater intensity when CWR are present as an audience (present but cannot pilfer). KFM ate 11.5%, re-larder-hoarded 17.9% and re-scatter-hoarded 1.3% of their scatter-hoarded seeds, and ate 29.3% of their larder-hoarded seeds when CWR were present as pilferers. A total of 12.8% of the seeds scatter-hoarded and 50% of seeds directly put on the ground by KFM were pilfered by CWR. CWR did not alter hoarding intensity in the presence of KFM and their stores cannot be pilfered by KFM. These results indicate that large-sized rodent species (more dominant) significantly increase the hoarding intensity of small-sized species and show a unidirectional pilferage of seeds cached by small-sized species. The behavioural differences between these two species may reduce competition for resources and promote coexistence between sympatric rodents.

Context‐dependent responses of food‐hoarding to competitors in Apodemus peninsulae: implications for coexistence among asymmetrical species

“…2c,d) (also see Zhang et al 2013b). This observation is consistent with our previous studies in A. peninsulae when it faced competitors of intraspecific individuals (Zhang et al , 2014b, or when its stores were completely lost (Huang et al 2011;Luo et al 2014), but not when it faced competitors of N. confucianus . In a study conducted in a tropical forest in southwestern China where N. confucianus performs both larder-hoarding and scatter-hoarding, N. confucianus increased larder-hoarding and shifted from scatter-hoarding to larder-hoarding when competitors (Rattus flavipectus) were present (Zhang et 123 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 al.…”

“…Due to differential capabilities of food competition (e.g. body size), sympatric species usually exhibit asymmetrical interactions in that some species (superior species hereafter) may have distinct advantages over others (subordinate species hereafter) Penner & Devenport 2011;Zhang et al 2014b;Dittel et al 2017). Asymmetrical competition in food-hoarding and pilferage has been observed to occur between intraspecific individuals that have different social statuses (e.g.…”

“…Zhang et al 2011;Huang et al 2019) and sympatric species that have different body sizes, hoarding habits, daily rhythms and/or diets (e.g. Vander Penner & Devenport 2011;Zhang et al 2014b;Dittel et al 2017;Gu et al 2017). In the case of asymmetrical interactions, context-dependent regulation of hoarding strategy is critically important for survival of the subordinate species that endures heavy cache losses, and coexistence of sympatric species that share similar habitats and diets.…”

“…For example, N. confucianus (larger-size, larder-hoarding) can pilfer caches from A. peninsulae (small-size, larder and scatter-hoarding), but the converse does not occur (Zhang et al 2014b). A. peninsulae space their hoarded seeds at a certain depth that can partially prevent pilferage by N. confucianus (Zhang et al 2014b). However, asymmetrical food competition among multiple species has not been studied.…”

Exclusion of interspecific competition reduces scatter‐hoarding of Siberian chipmunk Tamias sibiricus: A field study

“…Placement of acorns on the platforms in our study not only reduced interspecific competition from A. peninsulae and M. rufocanus but also relatively increased per capita seed abundance by reducing the abundance of competitive seed predators. Food-hoarding behavior in animals can be regulated by interspecific and/ or intraspecific competition between sympatric species that share the same ecological niches (Jiao et al 2011;Zhang et al 2011Zhang et al , 2014. Our study showed that seed consumption by T. sibiricus in seed stations was significantly decreased but scatter hoarding increased in the presence of potential interspecific competition.…”