Microtine Rodents Research Articles

Climate Change and Herbivores: Forty Years in a Bunchgrass Prairie.

Wild herbivore responses to anthropogenic climate change are often projected to be habitat and geographic range shifts as warmer conditions reduce the quantity and nutritional quality of forage plants, which makes species presence/absence a focus. Since 1978, herbivore abundances at the National Bison Range, MT, USA, were measured for grasshoppers (catch-effort), microtine rodents (runway density), and ungulates (drives and round-ups), along with climate and vegetation quantity (biomass) and quality (nitrogen content and chemical solubility related to digestibility). Counter to expectation with warming and drying, forage biomass increased as grass biomass increased more than dicot biomass decreased, and forage quality (solubility) increased. Consequently, herbivores that consume a grass diet (>25% grass: certain grasshoppers, microtines, bighorn sheep, elk, bison) increased in abundance, while herbivores consuming less grass declined (certain grasshoppers, pronghorn, whitetail, and mule deer). The result is an 18% increase in herbivore abundance and herbivory, counter to climate change expectations. Historically, grasshoppers consumed 46% more vegetation than mammals; now, they consume only 14% more, as grasshoppers did not increase as expected with climate change. Therefore, herbivores respond rapidly to climate-induced vegetation changes, and this is not a simple loss/addition of species, but changing trophic dynamics, which requires more knowledge of ecosystem dynamics.

How do microtine rodent abundance, snow and landscape parameters influence pine marten Martes martes population dynamics?

The pine marten (Martes martes) occupies the northernmost extent of its distribution in Norway, where microtine rodents are an important food item. The relationship between microtine rodent abundance and pine marten population dynamics is not well understood. In this paper, we examined this relationship and tested if environmental factors (e.g. snow depth, elevation, mature spruce forest density and agricultural land density) modulate pine marten population dynamics. We calculated pine marten abundance indices using data collected from 593 unique snow transects surveyed between 2003 and 2014 in Hedmark, Norway. We employed a Partial Rate Correlation Function to identify potential cyclicity in pine marten populations. We did not observe any cyclical patterns in pine marten populations within our short time series. Instead, their population appeared to be directly density-dependent. Although the population growth rate of pine marten tended to increase with increasing elevation, it was not affected by individual variables including a microtine rodent abundance index and snow depth. However, the annual growth rate of pine marten populations was positively affected by the interaction between the microtine rodent abundance index and increasing elevation. Pine marten abundance increased with microtine rodent abundance, elevation, snow depth and density of mature spruce forest, but decreased with increasing agricultural land density. Pine martens are opportunistic diet generalists that can switch between prey and cache food for later consumption. They are also strongly territorial with delayed implantation and are slow to respond to environmental changes due to their relatively low reproductive potential. These life-history traits may mitigate the effects of fluctuating microtine rodent abundance on pine marten reproduction and survival. Nevertheless, our findings suggest that microtine rodents still serve as important prey which can influence the population dynamics of pine martens in higher elevation habitats where alternative prey may be less available.

Pine marten predation of common goldeneye nests: Effects of cavity age and habitat override any effect of microtine rodent abundance.

According to the alternative prey hypothesis (APH), the temporal synchrony in population fluctuations of microtine rodents and other small herbivores in boreal areas is caused by generalist predators with numerical and functional response to microtines, leading to an increased predation of prey alternative to microtines in the low phase of the microtine population fluctuations. The tree-climbing pine marten (Martes martes) is a food generalist that includes bird eggs among its alternative prey, also eggs of the cavity-nesting common goldeneye (Bucephala clangula). We used long-term data to test whether pine marten predation of goldeneye eggs in nest boxes varied as predicted by the APH. As a measure of microtine abundance at the time of nesting, we applied two measures. First, for goldeneye nests located <40 km from our microtine trapping site, we applied the trapping index of microtine rodents. Second, to also use data from nests located >40 km from our microtine trapping site, and from nests in years when trapping was not conducted, we used two proxies for the microtine abundance: whether boreal owls (Aegolius funereus) nested in any of our boxes <40 km from each goldeneye nest and the average clutch size of these boreal owls. The probability of predation of a goldeneye nest was independent of the microtine trapping index and independent of the proxies for microtine abundance. However, it increased with cavity age, taken as the number of nesting seasons elapsed since the actual nest box was installed, and declined with distance from habitat with forest canopy. The effect of cavity age confirms that the long-term spatial memory of pine marten is an important factor in the pattern of its predation on nests in tree cavities.

Climate change drives substantial decline of understorey species richness and abundance in Norway spruce forests during 32 years of vegetation monitoring

AbstractQuestionsObservations in permanent forest vegetation plots in Norway and elsewhere indicate that complex changes have taken place over the period 1988–2020. These observations are summarised in the “climate‐induced understorey change (CIUC)” hypothesis, i.e. that the understorey vegetation of old‐growth boreal forests in Norway undergoes significant long‐term changes and that these changes are consistent with the ongoing climate change as an important driver. Seven testable predictions were derived from the CIUC hypothesis.LocationNorway.MethodsVegetation has been monitored in a total of 458 permanently marked plots, each 1 m2, in nine old‐growth forest sites dominated by Picea abies at intervals of 5–8 years over the 32‐year study period. For each of the 52 combinations of site and year, we obtained response variables for the abundance of single species, abundance and species density of taxonomic–ecological species groups and two size classes of cryptogams, and site species richness. All of these variables were subjected to linear regression modelling with site and year as predictors.ResultsMean annual temperature, growing‐season length and the number of days with precipitation were higher in the study period than in the preceding ca. 30‐year period, resulting in increasingly favourable conditions for bryophyte growth. Site species richness decreased by 13% over the 32‐year study period. On average, group abundance of vascular plants decreased by 24% (decrease in forbs: 38%). Patterns of group abundance change differed among cryptogam groups: although peat‐moss abundance increased by 39%, the abundance of mosses, hepatics and lichens decreased by 13%, 49% and 67%, respectively. Group abundance of small cryptogams decreased by 61%, whereas a 13% increase was found for large cryptogams. Of 61 single species tested for abundance change, a significant decrease was found for 43 species, whereas a significant increase was found only for 6 species.ConclusionsThe major patterns of change in species richness, group species density and group abundance observed over the 32‐year study period accord with most predictions from the CIUC hypothesis and are interpreted as direct and indirect responses to climate change, partly mediated through changes in the population dynamics of microtine rodents. The more favourable climate for bryophyte growth explains the observed increase for a few large bryophyte species, whereas the decrease observed for small mosses and hepatics is interpreted as an indirect amensalistic effect, brought about by shading and burial in mats of larger species and accelerated by reduced fine‐scale disturbance by microtine rodents. Indirect effects of a thicker moss mat most likely drive the vascular plant decline although long‐term effects of tree‐stand dynamics and former logging cannot be completely ruled out. Our results suggest that the ongoing climate change has extensive, cascading effects on boreal forest ecosystems. The importance of long time‐series of permanent vegetation plots for detecting and understanding the effects of climate change on boreal forests is emphasised.

Novel frontier in wildlife monitoring: Identification of small rodent species from fecal pellets using near-infrared reflectance spectroscopy (NIRS).

Small rodents are prevalent and functionally important across the world's biomes, making their monitoring salient for ecosystem management, conservation, forestry, and agriculture. There is a growing need for cost-effective and noninvasive methods for large-scale, intensive sampling. Fecal pellet counts readily provide relative abundance indices, and given suitable analytical methods, feces could also allow for the determination of multiple ecological and physiological variables, including community composition. In this context, we developed calibration models for rodent taxonomic determination using fecal near-infrared reflectance spectroscopy (fNIRS). Our results demonstrate fNIRS as an accurate and robust method for predicting genus and species identity of five coexisting subarctic microtine rodent species. We show that sample exposure to weathering increases the method's accuracy, indicating its suitability for samples collected from the field. Diet was not a major determinant of species prediction accuracy in our samples, as diet exhibited large variation and overlap between species. fNIRS could also be applied across regions, as calibration models including samples from two regions provided a good prediction accuracy for both regions. We show fNIRS as a fast and cost-efficient high-throughput method for rodent taxonomic determination, with the potential for cross-regional calibrations and the use on field-collected samples. Importantly, appeal lies in the versatility of fNIRS. In addition to rodent population censuses, fNIRS can provide information on demography, fecal nutrients, stress hormones, and even disease. Given the development of such calibration models, fNIRS analytics could complement novel genetic methods and greatly support ecosystem- and interaction-based approaches to monitoring.

Hawk owl irruptions: spatial and temporal variation in rodent abundance drive push and pull dynamics

Bird irruptions are thought to be triggered by low food availability in breeding areas, thereby causing emigration (push factor). However, few studies have tested whether emigrating individuals are drawn towards areas of high food availability (pull factor). The Northern hawk owl (Surnia ulula), a rodent specialist, occurs irruptively to southern parts of Fennoscandia. We analysed whether irruption size during 1980–2020 in southeastern Norway was related to rodent abundance at four sites 450–990 km to the north-northeast (potential source areas) and at two sites in southeastern Norway to test push and pull dynamics of irruptions. Irruptions occurred when rodent abundance in potential source areas were low, supporting the push hypothesis. High rodent abundance in potential source areas 1–2 years before irruptions suggested that irruptions were preceded by high reproduction. Upon arrival to southeastern Norway, hawk owls did not encounter high rodent abundance in their main habitat (boreal forest). However, hawk owls stayed in boreal forest in hills in years with higher microtine rodent abundance, but occurred in farmland areas in the lowlands when microtine rodents were less abundant. Use of lowlands coincided with higher than median numbers of wood mouse (Apodemus sylvaticus) for 87% of the hawk owls settling in the lowlands, thus suggesting support for the pull hypothesis. In conclusion, hawk owl irruptions to southern Fennoscandia were triggered by low food availability in northern areas (push factor), and appeared to be drawn by high food availability in southeastern Norway to some degree (pull factor).

Possible impact of winter conditions and summer temperature on bank vole (Myodes glareolus) population fluctuations in Central Norway

In recent decades, population fluctuations of microtine rodents have frequently faded out in parts of northern Europe, possibly because of climate change. Weather events may affect the rodents directly, but also indirectly, by acting on factors that generate population fluctuations. However, few studies have addressed the latter aspect. A species well suited for such a study is the bank vole (Myodes glareolus), which usually increases in number after a year with high seed production of bilberry (Vaccinium myrtillus). We analysed two snap-trapping time series of bank vole from Central Norway. When controlling for the impact of seed production of bilberry and Norway spruce (Picea abies), the number of bank voles trapped in the low-altitude area was negatively related to a summer temperature index of the two previous years, possibly because of the impact of temperature on the nutritional status of food plants. In the area situated at the highest altitude, there was a negative relationship with the winter NAO-index and a positive relationship with a snow depth index. Wet and mild winters are assumed to give unfavourable snow conditions, with alternating thawing and freezing, sometimes also creating an ice-layer at ground level, whereas a sufficient thick snow cover protects the rodents in periods with critical low temperatures. We conclude that an understanding of the ultimate cause of population fluctuations is needed to reveal the disturbing effects of weather events or other factors.

Vegetation cover and spatial distribution of small mammals in the conditions of woodland large city park (Nizhny Novgorod)

The paper is devoted to the study of ecological connectivity vegetation cover and microtine rodents spatial distribution in the conditions of the Nizhny Novgorod woodland park. The oak forest of National Research Lobachevsky State University of Nizhny Novgorod Botanical Garden with partial anthropogenic transformation was chosen as a site of the study. We used five various plant communities represented by linden trees. The dominant in all ecosystems on the test areas is the red vole (73%), the codominant is the pygmy wood mouse (21%). The yellow-necked mouse has been observed only in several communities. It has been revealed that a decrease in the biodiversity of plant communities due to an increase in the degree of individual species dominance marked by BergerParker index doesnt entail significant negative consequences for small mammals. It is possible that the dominants in vegetation cover create a favorable microclimate for small mammals. The PCA analysis shows the presence of two significant factors for the distribution of microtine rodents. The first factor is associated with the balance of humidity and illumination, the second with nitrogen availability in combination with low illumination. The ecological divergence of niches in two species of mice (pygmy wood mouse and yellow-necked mouse) was observed. In relation to the projective cover, the bank vole occurs both at very high (90%) and low (30%) values, which confirms the ecological plasticity of that species. For yellow-necked and pygmy wood mice, the optimal values of projective cover in studied communities range from 70 to 90%. However, yellow-necked mice can also live in plant communities with a plant cover index about 4050%.

Predation of boreal owl nests by pine martens in the boreal forest does not vary as predicted by the alternative prey hypothesis

The alternative prey hypothesis (APH) states that temporally synchronous population fluctuations of microtine rodents and other small herbivores are caused by generalist predators that show functional and numerical responses to the abundance of microtines. This would lead to an increased predation of alternative prey in the low phase of the microtine population fluctuations. One candidate for such a predator is the tree-climbing pine marten (Martes martes), which includes bird eggs in its diet, among them eggs of the cavity-nesting boreal owl (Aegolius funereus). I used long-term data to test whether pine marten predation of boreal owl eggs in nest boxes varied as predicted by the APH. The probability of predation of owl nests situated < 45 km from a site where microtines were trapped in spring during four decades increased with microtine trapping index, which is opposite to the prediction from the APH. As the data set was limited to one nest per box, I extended it spatially and temporally using the clutch size of each boreal owl nest as a proxy for the actual microtine abundance at the site. The probability of nest predation increased with clutch size. However, the effects of microtine index and owl clutch size became non-significant when I controlled for habitat, and in particular cavity age, which had an overriding effect. The increase in predation probability with cavity age suggests that the long-term spatial memory of pine marten is an important factor in the pattern of its nest predation in tree cavities.

Landscape-scale habitat associations of small mammals on the western coast of Hudson Bay

Availability of suitable habitat affects the distribution and abundance of Arctic fauna, influencing how species respond to climate change and disturbance from resource extraction in the region. We surveyed Arctic ground squirrels (Urocitellus parryii (Richardson, 1825)) using distance sampling transects and concurrently counted microtine rodent burrows. Abundance of Arctic ground squirrels and microtine burrows was positively correlated with terrain ruggedness. Microtine burrows were more abundant inland and in areas with freshwater, whereas Arctic ground squirrels were more often found at low elevation without freshwater. Arctic ground squirrel abundance was positively related to the normalized difference water index, a proxy for vegetation water content, whereas microtine burrows were weakly correlated with the normalized difference vegetation index. Our study highlights the habitat associations of ecologically significant small mammals in an underrepresented Arctic study area.

Age structure in a newly established and increasing population: initially high proportion of young birds among nesting Great Grey Owls

The mechanisms behind expansions of the distribution of a bird species and the ensuing establishment of new populations are poorly known. The distribution of Great Grey Owl (Strix nebulosa) in the western Palearctic has generally expanded towards southwest during the past fifty years, and particularly so in Fennoscandia. In the past decade, the recorded breeding population in Norway, confined to Hedmark county bordering Sweden, increased from 1 pair in 2009 to > 100 pairs in 2017–2018, extending the southwestern border of the distribution > 100 km. We studied the age structure of this expanding population based on the molting pattern of the wing feathers of birds captured at the nest site for banding and of non-captured birds photographed in flight. In Fennoscandia the Great Grey Owl relies on shrews and microtine rodents, which usually fluctuate in 3–4 years cycles. The proportion of 1-year old birds among the nesting Great Grey Owls was higher in peak year two of each small mammal population cycle (2011, 2014 and 2018) than in peak year one (2010, 2013 and 2017), and was particularly high (77%) in 2011 when the owl population was far lower (22 nestings recorded) than in later corresponding years (64 nestings in 2014 and 103 in 2018). Thus, this population seems to have been founded to a large extent by birds nesting as 1 year olds, and most likely having dispersed from Sweden. The ability to determine the age of Great Grey Owls without having to capture them extended our data set, in particular for males, which are more reluctant to attack intruders at the nest site and, therefore, less likely to be captured for banding. Being able to age a bird without having to capture it is important, because trapping does not sample a bird population randomly.

A stochastic structured metapopulation model to assess recovery scenarios of patchily distributed endangered species: Case study for a Mojave Desert rodent.

While metapopulation theory offers tractable means to understand extinction risks for patchily-distributed endangered species, real systems often feature discrepant patch quality and accessibility, complex influences of environmental stochasticity, and regional and temporal autocorrelation. Spatially structured metapopulation models are flexible and can use real data but often at the cost of generality. Particularly as resources for management of such species are often critically limited, endangered species management guided by metapopulation modeling requires incorporation of biological realism. Here we developed a flexible, stochastic spatially structured metapopulation model of the profoundly endangered Amargosa vole, a microtine rodent with an extant population of only a few hundred individuals within 1km2 of habitat in the Mojave Desert. Drought and water insecurity are increasing extinction risks considerably. We modelled subpopulation demographics using a Ricker-like model with migration implemented in an incidence function metapopulation model. A set of scenarios was used to assess the effect of anthropogenic stressors or management actions on expected time to extinction (Te) including: 1) wildland fire, 2) anthropogenically-mediated losses of hydrologic flows, 3) drought, 4) intentional expansion of existing patches into ‘megamarshes’ (i.e. via restoration/enhancement), and 5) additive impacts of multiple influences. In isolation, marshes could be sources or sinks, but spatial context within the full metapopulation including adjacency could alter relative impacts of subpopulations on all other subpopulations. The greatest reductions in persistence occurred in scenarios simulated with impacts from drought in combination with fire or anthropogenically-mediated losses of hydrologic flows. Optimal actions to improve persistence were to prevent distant and smaller marshes from acting as sinks through strategic creation of megamarshes that act as sources of voles and stepping-stones. This research reinforces that management resources expended without guidance from empirically-based modeling can actually harm species’ persistence. This metapopulation-PVA tool could easily be implemented for other patchily-distributed endangered species and allow managers to maximize scarce resources to improve the likelihood of endangered species persistence.

Vegetation cover and microtine rodents spatial distribution under conditions of Nizhny Novgorod oakwood

This paper deals with the problem of the connection between small mammals spatial distribution and the vegetation cover. The study was carried out during the summer period of 2018 and 2019 in the landscape protected area Oakwood of the NNSU Botanical Garden in the province of Nizhny Novgorod. Three relevs were set up in various plant associations: Ulmetum pulmonarioso-asaroso-aegopodiosum, Acereto-Tilietum pulmonarioso-impatienosum (noli-tangerae), Querceto-Acereto-Tilietum asareto-aegopodiosum. A standard geobotanical description was carried out according to the generally accepted method using a series of Raunkier sites registration. Microtine rodents were trapped by standart traps and live traps. The caught animals turned out to belong to 2 genera and 3 species: the bank vole Myodes glareolus Schreber, the pygmy wood mouse Apodemus uralensis Pallas, and the field mouse Apodemus agrarius Pallas. The low population size of animals, as well as the fact that Apodemus agrarius is a co-dominant, may indirectly indicate the anthropogenic pressure in the investigated oak groves. Ecological plasticity of the species Myodes glareolus has been confirmed. Bank voles inhabit micro-habitats with the average data of illumination as well as shaded ones. In general, the vegetation projective cover and the presence of Norway maple undergrowth are crucial for the microtine rodents spatial distribution. Small mammals choose sites with a minimum number of Acer platanoides undergrowth, and gravitate to places where the projective cover of grass has moderate rates (from 35 to 50%). The Principal Component Analysis (PCA) using a vegetation cover species spectrum showed the presence of a significant factor for microtine rodents, which is associated with nitrophilous species (common nettle and touch-me-not balsam). The presence of those plants may indicate a significant anthropogenic pressure on the vegetation cover. In addition, it is important that plants belong to a particular eco-coenotic group. The species Myodes glareolus and Apodemus agrarius differ on the nemoral factor, and their ecological niches do not overlap.

PALAEONTOLOGY, AGE, PALAEOENVIRONMENT AND PALAEOECOLOGY OF THE KAREWA INTERMONTANE BASIN OF KASHMIR (J&amp;K, INDIA)

A rich assemblage of vertebrate fossils, especially fish and mammals, has been recovered from the Plio—Pleistocene Karewa deposits of Kashmir (J &amp; K, India). Microtine rodents and insectivores, including some new taxa and first reports, form the most significant component of the assemblage. The Karewa vertebrate palaeontology is correlated with the magnetic polarity time scale. The Plio—Pleistocene boundary in Karewas is marked by the appearance of microtine rodents. The fossil assemblage is an admixture of high altitude and Iow altitude fauna. The fauna indicates the occurrence of a mosaic of dominant grassland and wooded grassland with some bush cover and wooded areas. A dominant lacustrine with some glacio—fluvial and aeolian environments are indicated for the Karewa sediments.

Food of a Chinese jumping mouse, Eozapus setchuanus (Pousargues, 1896)

Abstract This note is the only information on food of this species. Food from the stomach was examined using a binocular dissecting microscope. Results from this analysis indicate that the food of this species is similar to that of other zapodids, consisting of several different food items, rather than to the finely ground green vegetation eaten by microtine rodents.

Cenozoic vertebrate biostratigraphy of South Carolina, U.S.A., and additions to the fauna

Study of vertebrate fossils from the South Carolina Coastal Plain played a significant role in the early history of vertebrate paleontology as a scientific discipline in North America. However, a clear understanding of the state’s vertebrate biostratigraphy has been greatly hindered by the paucity of well-exposed fossil-bearing stratigraphic sections and a complicated subsurface stratigraphy. Most units, particularly those of Neogene and Quaternary age, exist as thin veneers of marine or estuarine sediments that typically occur as infilled topographic lows or erosional remnants as determined primarily from borehole stratigraphy. Hence, lateral continuity can be difficult to confirm over broad geographic areas often resulting inconfusion insofar as vertebrate fossil provenance is concerned. The evaluation of vertebrate fossils from the South Carolina Coastal Plain presented here, and of the geologic units from which they originated, or are thought to have originated, results in the first modern biostratigraphic framework for the known Cenozoic record of the state. Results provide (1) updated correlations of many units to the most recent, astronomically-tuned marine oxygen isotope stages; (2) the first viverravid from the Atlantic Coastal Plain, Didymictis proteus; (3) new information on the timing of certain Neotropical immigrants into the Southeast during the Great American Biotic Interchange, including the oldest record of Erethizon in this region and the oldest records of capybara in the USA; (4) the possible oldest record of the microtine rodent Allophaiomys pliocaenicus in the USA; (5) new details on the unit of origin for the type specimen of the archaeocete Dorudon serratus; and (6) new details on the ontogeny of the early odontocete Agorophius pygmaeus. New taxonomic records from South Carolina include Glyptotherium texanum, Holmesina floridanus, Ondatra idahoensis, Erethizon ?bathygnathum, Leopardus amnicola, Miracinonyx ?trumani, Canis lepophagus, Canis latrans, Phocanella pumila, Callophoca obscura, Monatherium sp., Anchippus texanus, Subhyracodon mitis, Aphelops ?malacorhinus, Teleoceras ?guymonense, and Perchoerus sp. New specimens of previously recorded taxa are also noted.

Activity patterns in mammals: Circadian dominance challenged.

The evidence that diel patterns of physiology and behaviour in mammals are governed by circadian ‘clocks’ is based almost entirely on studies of nocturnal rodents. The emergent circadian paradigm, however, neglects the roles of energy metabolism and alimentary function (feeding and digestion) as determinants of activity pattern. The temporal control of activity varies widely across taxa, and ungulates, microtine rodents, and insectivores provide examples in which circadian timekeeping is vestigial. The nocturnal rodent/human paradigm of circadian organisation is unhelpful when considering the broader manifestation of activity patterns in mammals.

Evolutionary diversity as a catalyst for biological discovery.

The tremendous diversity of animal behaviors has inspired generations of scientists from an array of biological disciplines. To complement investigations of ecological and evolutionary factors contributing to behavioral evolution, modern sequencing, gene editing, computational and neuroscience tools now provide a means to discover the proximate mechanisms upon which natural selection acts to generate behavioral diversity. Social behaviors are motivated behaviors that can differ tremendously between closely related species, suggesting phylogenetic plasticity in their underlying biological mechanisms. In addition, convergent evolution has repeatedly given rise to similar forms of social behavior and mating systems in distantly related species. Social behavioral divergence and convergence provides an entry point for understanding the neurogenetic mechanisms contributing to behavioral diversity. We argue that the greatest strides in discovering mechanisms contributing to social behavioral diversity will be achieved through integration of interdisciplinary comparative approaches with modern tools in diverse species systems. We review recent advances and future potential for discovering mechanisms underlying social behavioral variation; highlighting patterns of social behavioral evolution, oxytocin and vasopressin neuropeptide systems, genetic/transcriptional "toolkits," modern experimental tools, and alternative species systems, with particular emphasis on Microtine rodents and Lake Malawi cichlid fishes.

Cyclic small rodents in boreal forests and the effects of even-aged forest management: Patterns and predictions from a long-term study in southeastern Norway

Small mammals, especially microtine rodents, play an important role in the dynamics of boreal forest ecosystems. Even-aged forest management, in which old, semi-natural forests are converted to clear-cuts and culturally regenerated stands, is expected to have pronounced impact on the abundance and composition of this group of animals due to changes in the understory vegetation. During a 39 year-period we sampled autumn numbers of small mammals in uncut, semi-natural old forest and in recent clearcuts, supplemented by a 7-year sample from middle-aged plantations. Field voles Microtus agrestis were almost exclusively trapped in clearcuts. Bank voles Myodes glareolus dominated in the old forest, but reached equal or higher densities than field voles in clearcuts. Here, their combined abundance exceeded that of bank voles in old forest. Some years, wood lemmings Myopus schisticolor contributed significantly to vole abundance in old forest. Other rodents Apodemus spp. were rarely captured, mainly in clearcuts, and shrews Sorex spp. numbered <15 percent of the total number of captured animals. Throughout the whole period we discerned 11 vole cycles, with highest peaks in bank voles in old forest. After high numbers during the 1980s, abundances of all species fell markedly during the 1990s, most distinctively in clearcuts, where the field vole almost totally disappeared. From the late 2000s, abundances of all species returned to pre-1990 levels and beyond. In the early and late periods, combined vole numbers were 26% higher in clearcuts compared to old forest, whereas the opposite was true in the middle period. In middle-aged plantations, bank voles numbered only one third of what it was in clearcuts and old forest, and other voles were rarely trapped. The results support the general notion that bank voles thrive in bilberry-rich, older forest and field voles in grass-dominated habitat. Contrary to general assertions, bank vole was abundant also in clearcuts, possibly due to invasion from surrounding old forest, but peak densities were lower than in old forest, possibly due to suppression by field voles. The variation of small mammals in forest age classes concurred closely with recent results reported from Finland. On a landscape scale, the results from these two and other studies predict that the total biomass of small rodents will be reduced by even-aged forest management, not because of conversion of older, semi-natural forest to clearcuts, but because of a decline in numbers in middle-aged and older, secondary forests.

Prairie Voles as a Model for Understanding the Genetic and Epigenetic Regulation of Attachment Behaviors.

Over a lifetime, humans build relationships with family, friends, and partners that are critically important for our mental and physical health. Unlike commonly used laboratory mice and rats, Microtine rodents provide a unique model to study the neurobiology underlying pair bonding and the selective attachments that form between adults. Comparisons between monogamous prairie voles and the closely related but nonmonogamous meadow and montane voles have revealed that brain-region-specific neuropeptide receptor patterning modulates social behavior between and within species. In particular, diversity in vasopressin 1a receptor (V1aR) distribution has been linked to individual and species differences in monogamy-related behaviors such as partner preference, mate guarding, and space use. Given the importance of differential receptor expression for regulating social behavior, a critical question has emerged: What are the genetic and epigenetic mechanisms that underlie brain-region-specific receptor patterns? This review will summarize what is known about how the vasopressin (AVP)-V1aR axis regulates social behaviors via signaling in discrete brain regions. From this work, we propose that brain-region-specific regulatory mechanisms facilitate robust evolvability of V1aR expression to generate diverse sociobehavioral traits. Translationally, we provide a perspective on how these studies have contributed to our understanding of human social behaviors and how brain-region-specific regulatory mechanisms might be harnessed for targeted therapies to treat social deficits in psychiatric disorders such as depression, complicated grief, and autism spectrum disorder.