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Northern red‐backed voles (Clethrionomys rutilus) are an important species in the boreal forest ecosystem, both as herbivores and as a key food source for many mammalian and avian predators. They exhibit dramatic inter‐ and intra‐annual population fluctuations, for which causes are not entirely known. We monitored northern red‐backed vole densities in Denali National Park and Preserve through time with the goal of examining how environmental factors influenced density over time. Using a 30‐year record of mark‐recapture data, we used spatially explicit capture‐recapture methods to estimate autumn and early summer densities each year. We assessed cyclic patterns in density, variation in amplitude, and any periodicity of population fluctuations using post hoc linear modeling. We found that the vole population appeared to be cyclic with a 2–4 year period, although the pattern varied somewhat among sampling sites. Our results indicated an association between white spruce (Picea glauca) seed production and vole density, implying white spruce seeds were either an important source of food during winter seasons, or that the environmental triggers that promote high seed fall were also associated with increased vole density. We also found a negative effect of an autumn harshness index, indicating winter conditions play a role in vole density in the following season. Finally, we found evidence of a negative density‐dependent relationship between autumn and early summer. Together, these findings suggest a system in which density dependence and cyclic relationships are irregular but highly influential, with environmental effects capable of enhancing or moderating their impact. Continued monitoring of voles, alongside more thorough assessments of environmental conditions, may provide additional insight into the complex population dynamics of this species. In this study, we analyzed 30 years of northern red‐backed vole population data from Denali National Park to examine how environmental factors influenced density over time. We found that this population showed cyclic population fluctuations with a 2–4 year period, with some variation between sampling sites, and that densities were positively associated with white spruce seed production and negatively influenced by harsh autumn conditions. This, coupled with evidence of density dependence between autumn and early summer, suggests a system in which density dependence and cyclic relationships are irregular but highly influential, with environmental effects capable of enhancing or moderating their impact.

In salmon‐rich environments, which once spanned much of the Northern Hemisphere, bears occur at exceptionally high densities. Salmon, by growing bear populations, have the potential to exert wide‐ranging effects on ecosystem processes. Salmon‐supported bears provide seed dispersal services to plants, and bear scats containing thousands of seeds may then be efficient nutritional resources for granivorous small mammals that also function as secondary seed dispersers while hoarding seeds for winter. We taxonomically identified and enumerated seeds in individual bear scats to characterize patterns of bear frugivory. We then combined estimates of seed abundance and digestible energy content to quantify the energy available to granivorous small mammals, and we quantified the proportion of the mouse population that could be supported by locally abundant bear populations in lowland salmon systems. We additionally monitored seed‐filled bear scats with remote cameras to quantify small mammal visitation rates, and live‐trapped small mammals seasonally to determine whether rodents visited bear scats proportional to their densities or whether some species preferentially selected for bear scats, and to assess whether seasonal variation in scat visitation was driven by density or selection. Bears were an important initial dispersal agent for 12 species of fruit, particularly devil's club (Oplopanax horridus) and blueberry (Vaccinium spp.), which occurred in 80% (5839 seeds/scat) and 50% (10,719 seeds/scat) of scats, respectively. Seeds in bear scats were intensively utilized and dispersed by small mammals, primarily scatter‐hoarding northwestern deer mice (Peromyscus keeni; 8.5 visits per day/4295 total visits) and larder‐hoarding northern red‐backed voles (Myodes rutilus; 2.2 visits per day/1099 total visits), with visitation rates proportional to the seasonal density of each species. Small mammals likely incurred significant nutritional benefits from seeds deposited in bear scats (kcal/scat, mean = 114, n = 71). In coastal Alaska riparian areas, bears are potentially capable of indirectly subsidizing the energy needs of 45–65% of local deer mouse populations. Thus, this work helps elucidate the role that salmon, by supporting abundant bears, plays in ecological communities via influencing seed dispersal and resource subsidies to the small mammals that compose the base of the food web.

Scansoriality (climbing) allows access to valuable resources in the arboreal niche and is widespread among mammals, yet little is known about how it originates from obligate terrestriality. The northern red-backed vole (Myodes rutilus) is a small, Holarctic rodent long presumed to be strictly terrestrial, yet 3 of its congeners (M. gapperi, M. glareolus, and M. californicus) have been observed climbing in trees. We conducted paired arboreal and ground trapping surveys in interior Alaska to investigate anecdotal accounts of tree-climbing behavior in M. rutilus. Results indicate that they readily climb up to 2 m above ground in trees of their own volition, a phenomenon heretofore undocumented in the literature. Camera trap videos show M. rutilus exhibiting behavior and dexterity—such as terminal branch arboreal quadrupedalism and head-first descent mediated by hindfoot rotation—generally associated with more arboreal species. Northern red-backed voles may therefore provide a new perspective on early stages of scansoriality in small-bodied mammals.

The complete mitogenome sequence of the northern red-backed vole (Myodes rutilus) was determined using long polymerase chain reaction (PCR). The genome was 16,296 bp in length and contained 13 protein-coding genes, 2 ribosomal RNA genes, 22 transfer RNA genes, 1 origin of L strand replication, and 1 control region. The overall base composition of the heavy strand is A (32.9%), C (27.0%), T (26.9%), and G (13.2%). The base compositions present clearly the A-T skew, which is most obvious in the control region and protein-coding genes. Mitochondrial genome analyses based on MP, ML, NJ, and Bayesian analyses yielded identical phylogenetic trees. Results of phylogenetic analysis showed that Myodes had close relationship with Eothenomys, and had distant relationship with Microtus, Cricetulus, Dicrostonyx, Peromyscus, and other genera of Cricetidae. This study verifies the evolutionary status of M. rutilus in Myodes at the molecular level.

Several parameters of energy and immune homeostasis in immature red-backed voles at different phases of the population cycle have been evaluated and compared over three cycles (2002–2009). It has been found that a specific morphophysiological type of population is characteristic of each phase of the cycle. The values of all physiological parameters recorded at high and low population densities significantly differ from each other, with their values being usually intermediate at a medium density. The level of most energy and immune parameters at the phase of population peak corresponds to that observed under stress. Supposedly, stress contributes to suppression of reproduction and increased mortality of the voles.

Study results on the condition of endogenous ethanol—acetaldehyde system in northern red-backed vole ( Myodes (= Clethrionomys ) rutilus Pallas, 1779), common species of northern latitudes, are presented. Concentrations of endogenous ethanol (EE) and acetaldehyde (EA) in blood, activities of alcohol dehydrogenase in ethanol oxidation reactions (ADH I ) and liver acetaldehyde (ADH II ) and aldehyde dehydrogenase (ALDH) reduction, and catalytic parameters of these enzymes are determined for winter and summer periods. Changes in ethanol—metabolizing dehydrogenase enzyme system in northern red-backed vole leading to statistically significant ( p < 0.01) increase in blood EE and EA concentrations compared to white nonpedigreed laboratory rats without adaptations to cold (especially in winter period) are determined to serve ecoadaptive, antistress functions, comprising one of the systems for regulation of metabolism intensity in small mammals inhabiting extreme northern conditions. Ecological—physiological functions of EE and EA system are increasing the organism’s resistance to the influence of cold temperatures and maintaining thermoregulation even under rapid, considerable environmental temperature drops.

To test the hypothesis of relationship between the age at maturity, metabolic rate, and life span of rodents, variation in bioenergetic parameters in northern red-backed voles (Myodes rutilus) was analyzed depending on their reproductive status and type of ontogeny. Standard metabolic rate was found to be significantly lower in young of the year that remained nonreproductive in the year of birth than in reproductive young of the year and overwintered voles. Maximal metabolic rate and the ability to maintain temperature homeostasis under cold exposure were independent of reproductive status and life history pattern but varied depending on phases of the population cycle, increasing in years with low animal abundance.

This article presents data on the genetic variability of the northern red-backed vole and the bank vole that live sympatrically in West Siberia. The two species of voles have comparable, relatively high indices of genetic variability of inter simple sequences repeats DNA. The proportion of polymorphic DNA markers is 95–98%, and the Nei’s genetic diversity index is 0.33–0.35. A total of 47–58% of allozyme loci in the voles are polymorphic, and the average heterozygosity per locus is 0.058 in the northern red-backed vole and 0.054 in the bank vole. Interpopulation differentiation is less pronounced in the red-backed vole ( F ST 0.293) compared to the bank vole ( F ST 0.475). Individuals of the hybrid line of the bank vole with the mitochondrial haplotype of the red-backed vole have been found by PCR typing of cytochrome b gene fragment of mtDNA. The distribution boundary of the hybrid line of bank voles goes farther to the northeast than was shown in earlier works. The proportion of hybrid specimens range from 2 to 34%. The indices of genetic variability in the hybrid line of the bank vole are lower than those of the parental species.

A comparative analysis of spatial population structure in the northern red-backed vole (Clethrionomys rutilus Pall.) and large-toothed red-backed vole (Cl. rufocanus Sund.) has been performed in the middle taiga zone of the Middle Irtysh region (Omsk oblast). Populations of these species are represented by sets of territorial groups whose numbers and spatial distribution change from year to year depending on the ratio of these species in a biotope and their population density. There is no significant interspecific competition between cohabitant Cl. rutilus and Cl. rufocanus. In particular, this follows from the fact that the population density and distribution pattern of one species are independent of those of the other species. It has been found that the size of home ranges in Cl. rutilus inversely depends on its population density, with that in Cl. rufocanus remaining approximately the same at different population densities, and that the structure of the resident part of the population in both species changes during the season, as voles from neighboring habitats or dispersing voles settle in the study area.[PUBLICATION ABSTRACT]

Sky islands, ecosystems found on geographically isolated mountain peaks, are among the most biodiverse ecosystems in the world but face a disproportionately high threat from climate change. High‐elevation, montane ecosystems, which are already at their upper altitudinal limits, are predicted to severely contract in response to climate change. The identification and conservation of refugia is an increasingly important approach for protecting biodiversity associated with imperiled ecosystems. We explored the spruce‐fir–northern hardwood ecotone as a possible refugium for mammals in the Southern Appalachian red spruce (Picea rubens)‐Fraser fir (Abies fraseri) sky islands. We conducted livetrapping, camera trapping, and ultrasonic acoustic surveys to characterize mammal diversity across the spruce‐fir–northern hardwood forest gradient on Grandfather Mountain and Roan Mountain Highlands in western North Carolina, USA. We detected four out of the five spruce‐fir‐associated small mammal species in both spruce‐fir and ecotone habitats. Mammal species richness, alpha diversity, and bat activity tended to be higher in the ecotone than in the other forest types on both mountains. Next, the abundance of small mammals associated with spruce‐fir was higher in the spruce‐fir and ecotone forests for one of the three species we were able to estimate. Together, our results suggest that the spruce‐fir–northern hardwood ecotone might serve as refugium for mammal species that are associated with spruce‐fir sky islands in the Southern Appalachian Mountains and mammalian conservation efforts in this biodiversity hotspot should consider focusing on the ecotone in addition to the adjacent spruce‐fir ecosystem. Sky islands are among the most biodiverse ecosystems in the world but face a disproportionately high threat from climate change. We examined the spruce‐fir–northern hardwood ecotone as a possible refugium for mammals in the Southern Appalachian red spruce (Picea rubens)–Fraser fir (Abies fraseri) sky islands. We detected spruce‐fir‐associated small mammal species in both spruce‐fir and ecotone habitats, wherein mammal species richness, alpha diversity, and bat activity tended to be higher in the ecotone than in the other forest types on both mountains. Together, our results suggest that the spruce‐fir–northern hardwood ecotone may serve as a key refugium for mammal species that are associated with spruce‐fir sky islands in the Southern Appalachian Mountains, and mammalian conservation efforts in this biodiversity hotspot should consider focusing on this ecotone in addition to the adjacent spruce‐fir ecosystem.