Niche Differentiation In Apodemus Peninsulae And Niviventer Confucianus In Donglingshan Area

Niche differentiation can promote coexistence of sympatric species that share similar habitats,diets,rhythm and/or foraging behaviors.Korean field mice(KFM),Apodemus peninsulae and Chinese white-bellied rats(CWR),Niviventer confucianus are common rodent species in DongLingshan area,northern China.The two noctural rodents inhabit in secondary forests and shrubs,eat and hoard seeds of the common local trees of Armeniaca sibirica,Amygdalus davidiana,Quercus wutaishanica etc.Some previous studies have looked at their hoarding behavior for seeds and interacted food pilfering,however,very few studies have looked at their niche differentiation at multiple levels of ecological factors.Thus,their coexistence has not been explained well in the study area.Here,I studied niche differentiation between KFM and CWR at different levels of micro-habitat selection,diet,active rhythm and foraging behavior to explore their coexistence in the study area.As I known,this is the first study to explore coexistence between sympatric species at multiple ecological factors.The results would enrich the theories of species coexistence,and provide references for ecological-based management of rodents.I found that:(1)seven variables of micro-habitat were significantly different between plot groups,indicating that the two rodent species had different habitat preference.KFM preferred for habitats with larger tree diameter at breast height,a relatively higher proportion of open land,greater shrub and herb height.Whereas CWR preferred for habitats with higher canopy coverage,more leaves coverage,and a relatively higher proportion of shrub coverage;(2)Analysis of chyme composition showed that the two rodent species fed on different food items,meanwhile,the food selection of them are different in different seasons.Stem and leaf are the primary food resources for both KFM and CWR in spring,and KFM would take more insects as the supplement of food,while CWR would get more roots instead.In summer and autumn,KFM and CWR would take seeds as the main food resource.For a supplement,KFM would take some stems and leaves,whereas CWR did not show any obvious preference to them;(3)Although KFM spent more time on activities outside nest compared to CWR,there was not significant difference in foraging time and drinking time between them.KFM was mainly in activity from 00:00 to 4:00 with two peaks around 21:00 and 3:00 respectively.CWR was mainly in activity from 19:00 to 01:00 with a peak around 24:00.In addition,the active duration and rate in different periods of time were also distinct from each other;(4)KFM preformed both scatter and larder hoarding behaviors,while CWR hoarded seeds in larder only or in scatter rarely.KFM exhibited a relatively stronger ability of cache excavating than CWR because KFM could discover more artificial caches than CWR,and this difference was significant when seeds were buried at 5-cm and 1-cm depth.When the two rodent species were provided seeds of Armeniaca sibirica(high fat and protein,low tannin and hard seed coat),Quercus wutaishanica(high starch,high tannin and thin seed coat)and Amygdalus davidiana synchronously,KFM preferred for Armeniaca sibirica seeds,wheareas CWR were more likely to harvest both Quercus wutaishanica and Armeniaca sibirica seeds.Armeniaca sibirica seeds are the main food source for both KFM and CWR,but CWR would take several Quercus wutaishanica seeds as a supplement,while KFM did not show any preference for Quercus wutaishanica seeds.KFM would Leave less seeds that intacted in site by contrasted with CWR.These results suggest that KFM and CWR had different preferences in several ecological factors,which probably facilitate their coexistence by reducing interspecific competition.