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

Abstract

Superior species may have distinct advantages over subordinates within asymmetrical interactions among sympatric animals. However, exactly how the subordinate species coexists with superior species is unknown. In the forests west of Beijing City, intense asymmetrical interactions of food competition exist among granivorous rodents (e.g. Apodemus peninsulae, Niviventer confucianus, Sciurotamias davidianus and Tscherskia triton) that have broadly overlapping habitats and diets but have varied body size (range 15–300 g), hoarding habits (scatter vs larder) and/or daily rhythm (diurnal vs nocturnal). The smallest rodent, A. peninsulae, which typically faces high competitive pressure from larger rodents, is an ideal model to explore how subordinate species coexist with superior species. Under semi‐natural enclosure conditions, we tested responses of seed‐hoarding behavior in A. peninsulae to intraspecific and interspecific competitors in the situations of pre‐competition (without competitor), competition (with competitor) and post‐competition (competitor removed). The results showed that for A. peninsulae, the intensity of larder‐hoarding increased and the intensity of scatter‐hoarding declined in the presence of intraspecifics and S. davidianus, whereas A. peninsulae ceased foraging and hoarding in the presence of N. confucianus and T. triton. A. peninsulae reduced intensity of hoarding outside the nest and moved more seeds into the nest for larder‐hoarding under competition from intraspecific individuals and S. davidianus. In most cases, the experimental animals could recover to their original state of pre‐competition when competitors were removed. These results suggest that subordinate species contextually regulate their food‐hoarding strategies according to different competitors, promoting species coexistence among sympatric animals that have asymmetrical food competition.

Effects of masting on seedling establishment of a rodent‐dispersed tree species in a warm‐temperate region, northern China

“…The plasticity of food hoarding strategies of rodents according to food abundance may partially explain the U‐shaped change of seed dispersal distance (Niu et al . 2020). Rodents appear to move seed further for hoarding to reduce competition and pilferage when seed abundance is relative low, and they tend to rapidly cache seeds around the sources to maximize food harvest when seed production is high and ephemeral (Jenkins & Peters 1992; Galvez et al .…”

Asymmetric competition for seeds between two sympatric food hoarding rodents: implications for coexistence

“…The cached foods of hoarders are often pilfered by intraor inter-specific competitors, which threaten the survival and reproduction of the hoarders (Vander Wall & Jenkins 2003;Gu et al 2017). Accordingly, food hoarders have evolved different strategies to reduce pilfering of their caches and replace lost caches by harvesting food from the source and/or pilfering caches from other hoarders (Vander Wall & Jenkins 2003;Dally et al 2006;Niu et al 2020a). Due to differences in hoarding behaviors (larder hoarding vs. scatter hoarding), ability to protect caches, and pilferage among sympatric animals, the results showed that the competition are usually asymmetric, in that some species (e.g.…”

“…small-sized species) (Vander Wall et al 2009;Penner & Devenport 2011;Zhang et al 2014a;Dittel et al 2017). Under the asymmetric interactions of food competition, competitive strategies of the subordinate species are considered in understanding species coexistence, but they are not yet fully understood (Niu et al 2020a).…”

“…Some rodents obviously have fewer advantages than other species when competing for seed sources and/or caches (i.e. asymmetric competition), but they can persist in the community over time (Vander Wall et al 2009;Dittel et al 2017;Gu et al 2017;Niu et al 2020a). How sympatric seed-eating rodents coexist with each other under the conditions of asymmetric competition is not fully clear (Vander Wall et al 2009;Niu et al 2020a).…”

Tracking Animal-Dispersed Seedlings Using 15N Xylem Injection Method

“…Most recently, Gu et al (2017) and White et al (2017) investigated the relationships between rodents and seeds at the individual level combining infrared radiation camera tracking and seed tagging. Although these methods have been used in many ecosystems for tracking seed dispersal, the main shortcoming is the influence of seed alteration on either seed choice by animals or the following seedling establishment (Levey and Sargent, 2000;Godoy and Jordano, 2001;Tewksbury et al, 2002;Hirsch et al, 2012a,b;Yi and Wang, 2015;Niu et al, 2020). Xiao and Zhang (2003) have well compared a majority of tracking methods, pointing out their advantages and limitations and potential implications in seed dispersal ecology.…”