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

Abstract

Asymmetric competition occurs when some species have distinct advantages over their competitors and is common in animals with overlapping habitats and diet. However, the mechanism allowing coexistence between asymmetric competitors is not fully clear. Chinese white‐bellied rats (Niviventer confucianus, CWR) and Korean field mice (Apodemus peninsulae, KFM) are common asymmetric competitors in shrublands and forests west of Beijing city. They share similar diet (e.g. plant seeds) and activity (nocturnal), but differ in body size (CWR are bigger than KFM), food hoarding habit (CWR: mainly larder hoarding; KFM: both larder and scatter hoarding), and ability to protect cached food (CWR are more aggressive than KFM). Here, we tested seed competition in 15 CWR–KFM pairs over a 10‐day period under semi‐natural enclosure conditions to uncover the differences in food hoarding, cache pilferage, and food protection between the 2 rodents, and discuss the implication for coexistence. Prior to pilferage, CWR harvested and ate more seeds than KFM. CWR tended to larder hoard seeds, whereas KFM preferred to scatter hoard seeds. Following pilferage, CWR increased consumption, decreased intensity of hoarding, and pilfered more caches from KFM than they lost, while KFM increased consumption more than they hoarded, and they preferred to hoard seeds in low and medium competition areas. Accordingly, both of the 2 rodent species increased their total energy consumption and hoarding following pilferage. Both rodent species tended to harvest seeds from the source, rather than pilfer caches from each other to compensate for cache loss via pilferage. Compared to CWR, KFM consumed fewer seeds when considering seed number, but hoarded more seeds when considering the seeds’ relative energy (energy of hoarded seeds/rodent body mass2/3) at the end of the trials. These results suggest that asymmetric competition for food exists between CWR and KFM, but differentiation in hoarding behavior could help the subordinate species (i.e. KFM) hoard more energy than the dominant species (i.e. CWR), and may contribute to their coexistence in the field.

Impacts of tree species on soil chemical properties in the reforested urban forests

“…Although we did not nd the role of Q. variabilis on urban soils, it doesn't mean this tree species is not important in urban reforestation. In contrary, the oak species usually produce nutritive acorns for rodents, birds and weevils, supporting a high number of animals (Meng et al 2022;Zhang et al 2024).…”

Behavioral adaptation of sympatric rodents to early germination of oak acorns: radicle pruning and embryo excision

“…Sympatric rodents often have different foraging strategies due to competition for food resources ( Lu and Zhang, 2008 ; Zhang et al., 2014b ; Meng et al., 2022 ). Our findings presented further evidence for these observations ( Zhang et al., 2013a ; Zhang et al., 2014a ; Gu et al., 2021 ).…”

“…In this study, we provided both germinating and nongerminating acorns of Q. variabilis (an early germinating oak species) to individual field food-hoarding rodents, including scatter hoarders and larder hoarders, with the former potentially having a greater impact on seedling establishment. We predicted that (1) there will be differences in acorn consumption and scatter-hoarding decisions of rodents with different morphological and behavioral characteristics, because differentiation in hoarding behavior may help sympatric species to harvest more energy, which contributes to their coexistence in the field ( Cheng et al., 2005 ; Meng et al., 2022 ); (2) rodents will remove the radicle or embryo of germinating acorns before hoarding, thereby reducing seed perishability in caches ( Steele et al., 2006 ; Yi et al., 2012a ); and (3) embryo-excised acorns are far less likely to germinate than those with radicles pruned or intact ones because the embryo is a necessary condition for maintaining seed germination ( Yi et al., 2013 ), and radicle-pruned acorns successfully regerminated when the radicle was unlignified ( Zhang et al., 2016 ).…”

Recovery of small rodents from open‐pit marble mining: effects on communities, populations, and individuals

“…Small rodents offer the advantages of being easy to monitor, highly diverse, and widely distributed mammals with a high reproductive rate, broad diet, and short lifespan, enhancing their sensitivity to indicate environmental change (Yakushov & Sheftel 2023). Small rodents contribute valuable ecosystem services; for example, they disperse seeds by caching any surplus seeds they do not consume (Meng et al 2023), where these seeds are harvested within the limited range of the rodent's territory (Lobo 2014). Predation on small rodents is also important to the diets of a variety of avian and mammalian predators in terrestrial food chains (Zhang et al 2021).…”

“…Small rodents contribute valuable ecosystem services; for example, they disperse seeds by caching any surplus seeds they do not consume (Meng et al. 2023), where these seeds are harvested within the limited range of the rodent's territory (Lobo 2014). Predation on small rodents is also important to the diets of a variety of avian and mammalian predators in terrestrial food chains (Zhang et al.…”