Resource partitioning confirmed by isotopic signatures allows small mammals to share seasonally flooded meadows

Abstract

Meadows in river deltas are characterized by a high diversity and abundance of small mammals. However, neither their spatial arrangement nor differences in their use of microhabitat can necessarily explain the dense co‐occurrence of sympatric species. We investigated how several small mammal species share a seasonally flooded meadow of limited size, testing predictions (P1) that herbivore, granivore, insectivore, and omnivore species are separated in time (dominant in different years), (P2) that sympatric species undergo isotopic partitioning, and (P3) that there are intraspecific differences in diet. Stable carbon and nitrogen isotope signatures in the hair of seven synantropic shrew, vole, and mice species were used as a proxy for their diet. We found that the three most abundant species in eight of the nine years were from different diet groups. However, based on the number of species in the functional groups, the state of small mammal community was considered unfavored in five out of the nine investigation years. In years with the greatest dominance of Apodemus agrarius , the small mammal community was characterized by decreased diversity and Micromys minutus was either in low abundance or absent. In 2014 and 2016, years of low abundance or absence of M. oeconomus , M. agrestis, and M. glareolus were both recorded in high numbers. Differences in the isotopic signatures of the three most abundant small mammal species in the community were clearly expressed and core areas in the isotopic space were separated, showing their dependence on different dietary resources. Intraspecific dietary separation between young and adult animals was observed only in M. oeconomus . Thus, the high species diversity of small mammals and the formation of their community in this investigated flooded meadow are maintained by isotopic partitioning (segregation in dietary space) and by changes in their number over time (shifting dominance).

Mow the Grass at the Mouse’s Peril: Diversity of Small Mammals in Commercial Fruit Farms

“…The number of lines per site depended on the size of the fruit farm, ranging from one to four. Despite the warning of [38,39] about the effects of removal trapping of small mammals on abundance and diversity, our data show no influence of short trap lines on the diversity and abundance of small mammals, even after long-term trapping of up to three times per year [40,41,42,43]. In this study, we trapped two times.…”

“…M. arvalis is one of the most numerous species in Central Europe [11], which may consume nearly 50% of the annual production of alfalfa during outbreaks [60]. An expansion of A. agrarius has been recorded in other European countries [61], and this requires special attention in Lithuania [43].…”

“…Based on our long-term small mammal studies [40,41,42,43,44,47,48], we suppose that the number of trapping sites (spatial replications) was enough to represent possible temporal changes in small mammal diversity and abundance (i.e., the results are representative). Earlier, different small mammal densities and number of species were found within the same year in forests, swamps, or meadows located several kilometers from each other [41,42,47,48].…”

“…Species richness was expressed as the number of trapped species, while the Shannon–Wiener diversity index, H, on the base of log 2 [45] was used as a measure of the diversity of the small mammal community and the dominance index, D, as a measure of dominance [19,45,46]. The diversity of the community was compared to other habitats and territories of varying sizes in Lithuania ([40,41,42,43,47,48]; Appendix B Table A1). Diversity estimates (including bootstrap, yielding 95% confidence interval) were calculated using PAST ver.…”

Stable Isotopes Reveal the Dominant Species to Have the Widest Trophic Niche of Three Syntopic Microtus Voles

“…Our study concentrated on the evaluation of the trophic niche of three Microtus vole species, being sympatric and syntopic at the same time [ 10 , 11 ]. All of these species are herbivores [ 12 , 13 , 14 , 15 ], though food of animal origin can constitute up to 4.5% of volume or 12.3% of frequency in the diet of the field vole [ 16 ].…”