A new species of Hipposideros is described from Vietnam. Morphologically, it is similar to taxa in the Hipposideros armiger complex but is substantially smaller. The new species, which has been found living sympatrically with H. armiger in Cat Ba National Park, is distinguished from it by size, acoustic characters, and differences in the mitochondrial DNA. Currently, the new taxon is known from Cat Ba Island in Ha Long Bay in northern Vietnam and from Chu Mom Ray National Park, which is situated on the mainland some 1,000 km to the south. It was collected in disturbed and primary forests.

Previous understanding of the relationships among genera of bats in the family Molossidae was based largely on phenetic analyses of morphological data. Relationships among the genera of this family have not been tested with molecular data and, thus, the objective of this study was to construct a phylogeny of representative members of free-tailed bats using DNA sequence data from 1 mitochondrial locus (Nicotinamide adenine dinucleotide dehydrogenase subunit 1 [ND1]) and 3 nuclear loci (dentin matrix protein 1 exon 6 [DMP1], beta fibrinogen intron 7 [βFIB], and recombination activating gene 2 [RAG2]) for members of the subfamily Molossinae and outgroups from the families Vespertilionidae and Natalidae. Data for each gene were analyzed separately using maximum-likelihood and Bayesian methods and also analyzed in a single combined analysis of a total of 3,216 base pairs. Divergence times were estimated from the combined data set using BEAST analysis. Few intergeneric relationships were significantly supported by mitochondrial data; however, monophyly of most genera was supported. Nuclear results supported a Chaerephon–Mops clade; a New World clade consisting of Eumops, Molossus, Promops, Molossops (including Neoplatymops), Cynomops, and Nyctinomops; and a basal divergence for Cheiromeles. Divergence analysis suggested a Paleocene origin for the family and a split between molossids in the Old World and New World around 29 million years ago. Generally, relationships recovered in our analyses reflected biogeographic proximity of species and did not support the hypotheses of relationship proposed by morphological data.

The pygmy rabbit (Brachylagus idahoensis), a leporid of the Great Basin and southern Wyoming, resides in habitats dominated by big sagebrush (Artemisia tridentata). Because of the patchy distribution of mature big sagebrush in southern Wyoming, we expected pygmy rabbits to exhibit genetic attributes associated with genetic isolation: high levels of spatially structured differentiation. We also predicted some reduction in genetic diversity in the peninsular Wyoming portion of the geographic range, relative to its Great Basin core. We used 14 microsatellite loci to compare genetic attributes between geographically distinct pygmy rabbit populations, and a subset of these microsatellite loci to compare with those of 2 sympatric cottontails (Sylvilagus spp.), both presumptive habitat generalists. Pygmy rabbits displayed moderate genetic diversity that was lower than that reported from locations near the core of the geographic range (Idaho and Montana). We observed only low levels of genetic differentiation in pygmy rabbits among sampling sites within Wyoming. Similarly, we observed low levels of differentiation in one species of cottontail sympatric with pygmy rabbits; however, the other species of sympatric cottontail displayed levels of differentiation congruent with those of populations at panmixia. Isolation-by-distance was the dominant genetic pattern observed, although examination of our data suggested that a 4-lane highway (Interstate 80) might affect gene flow measurably. In the recent evolutionary past, habitat connectivity and dispersal capacity for pygmy rabbits have been high enough to maintain gene flow among sites across southern Wyoming. Conservation of the species should focus on maintaining the connectivity among preferred habitats: old stands of big sagebrush.

Pleistocene climate fluctuations rearranged ecosystems, and influenced the contemporary distribution of modern species. Although specialist species were often restricted to isolated refugia by Pleistocene climate change, generalist species may have been less constrained in their distribution and movements. We used a combination of genetic data and previously published fossil data to investigate the phylogeography and contemporary population structure of a generalist species, the striped skunk (Mephitis mephitis). We sequenced a portion of the mitochondrial cytochrome-b gene (601 base pairs) and amplified 8 microsatellite loci from 314 striped skunk specimens. Phylogenetic analysis of the cytochrome-b gene revealed the presence of 4 distinct phylogroups, and examination of microsatellite data indicated a pattern of secondary contact among these clades. We infer from these data that during the Rancholabrean stage prior to the Illinoian glaciation, striped skunks emerged from a southern refugium in the Texas–Mexico region and colonized the southeastern United States, forming a 2nd, later refugium in the east. This colonization was followed by a 2nd dispersal event from the southern source population to west of the Rocky Mountains during the Illinoian glacial period. During the Sangamonian interglacial stage, 2 distinct subclades formed on either side of the Sierra Nevada. During the Holocene, the subclade that colonized the Great Basin then expanded east across the northern Rockies and recolonized the Great Plains to create an area of secondary contact with the southern phylogroup. Secondary contact occurred to a lesser extent with individuals from the eastern phylogroup east of the Mississippi River. It appears that periodic Pleistocene glacial expansions and retreats caused a series of range expansions and secondary contact events in this native North American species to create a complex pattern of population structure today.

Red foxes (Vulpes vulpes) are native to boreal and western montane portions of North America but their origins are unknown in many lowland areas of the United States. Red foxes were historically absent from much of the East Coast at the time of European settlement and did not become common until the mid-1800s. Some early naturalists described an apparent southward expansion of native foxes that coincided with anthropogenic habitat changes in the region. Alternatively, red foxes introduced from Europe during Colonial times may have become established in the east and subsequently expanded their range westward. The red fox also was absent historically from most lowland areas of the western United States. Extant populations of red foxes in those areas are considered to have arisen from intentional introductions from the east (and by extension are putatively European), escapes or releases from fur farms, or range expansions by native populations. To test these hypotheses we compared mitochondrial DNA sequences (cytochrome b and D-loop) from 110 individuals from 6 recently established populations to 327 native (primarily historical) individuals from Eurasia, Alaska, Canada, the northeastern United States, and montane areas in the western contiguous United States, and to 38 individuals from fur farms. We found no Eurasian haplotypes in North America, but found native haplotypes in recently established populations in the southeastern United States and in parts of the western United States. Red foxes from the southeastern United States were closely related to native populations in eastern Canada and the northeastern United States, suggesting that they originated from natural range expansions, not from translocation of European lineages, as was widely believed prior to this study. Similarly, recently established populations in the Great Basin and in western Oregon originated primarily from native populations in western montane regions, but also contained a few nonnative North American haplotypes. In contrast, populations in western Washington and southern California contained nonnative, highly admixed stock that clearly resulted from intracontinental translocations. Several common haplotypes in these populations originated in regions where fur-farm stocks originated. Although European red foxes translocated to the eastern United States during Colonial times may have contributed genetically to extant populations in that region, our findings suggest that most of the matrilineal ancestry of eastern red foxes originated in North America.

Alpine and arctic environments are thought to be more vulnerable to climate change than other lower-elevation and lower-latitude regions. Being both arctic and alpine distributed, the Alaska marmot (Marmota broweri) is uniquely suited to serve as a harbinger of the effects of climate change, yet it is the least-studied marmot species in North America. We investigated the phylogeography and genetic diversity of M. broweri throughout its known distribution in northern Alaska using the mitochondrial cytochrome b gene to better understand how post-Pleistocene changes and population fragmentation have structured genetic diversity. Our results show significant, although shallow, geographic structure among Alaska marmot populations. The diversity within and among populations is consistent with 2 phylogeographic hypotheses: Alaska marmots persisted in the eastern Brooks Range, Ray Mountains, and Kokrines Hills during the Pleistocene and have only recently expanded into the western Brooks Range; and the western Brooks Range served as a refugium as well and those populations have undergone a bottleneck resulting in reduced genetic variation in extant populations. Levels of mitochondrial deoxyribonucleic acid diversity are lower in M. broweri than in any other codistributed small mammal species and alpine mammal species with comparable data available. This is the 1st phylogeographic study of any marmot species and provides a baseline measure of the current structure and diversity within M. broweri.

Phylogenetic affinities of the late Miocene echimyid †Pampamys emmonsae Verzi, Vucetich, and Montalvo, 1995 (Huayquerian South American Land Mammal Age, central Argentina), were analyzed. In the most-parsimonious tree obtained, subfamilies of Echimyidae were nonmonophyletic (except for Dactylomyinae). Two major clades were recovered. One of them included the living fossorial Eumysopinae and the extinct †Theridomysops. The other clade grouped the terrestrial eumysopines Thrichomys (punaré) and Proechimys–Trinomys (spiny rats), and the arboreal eumysopines Mesomys (spiny tree-rats) Echimyinae–Dactylomyinae. †Pampamys was the sister genus of Thrichomys, suggesting the Huayquerian South American Land Mammal Age (>6.0 million years ago [mya] by biochronology) as a minimum age for the origin of the living genus. Both major echimyid clades recognized here are represented by simplified-molared species in the Huayquerian South American Land Mammal Age. This would be related to the expansion of open environments during the late Miocene, and the geographical bias of the fossiliferous Huayquerian deposits exposed mostly in southern South America.

Lemmings construct nests of grass and moss under the snow during winter, and counting these nests in spring is 1 method of obtaining an index of winter density and habitat use. We counted winter nests after snow melt on fixed grids on 5 areas scattered across the Canadian Arctic and compared these nest counts to population density estimated by mark–recapture on the same areas in spring and during the previous autumn. Collared lemmings were a common species in most areas, some sites had an abundance of brown lemmings, and only 2 sites had tundra voles. Winter nest counts were correlated with lemming densities estimated in the following spring (r_s  =  0.80, P < 0.001), but less well correlated with densities the previous autumn (r_s  =  0.55, P < 0.001). Winter nest counts can be used to predict spring lemming densities with a log-log regression that explains 64% of the observed variation. Winter nest counts are best treated as an approximate index and should not be used when precise, quantitative lemming density estimates are required. Nest counts also can be used to provide general information about habitat-use in winter, predation rates by weasels, and the extent of winter breeding.

The Amur tiger, Panthera tigris altaica, is currently distributed across the southern part of the Russian Far East and parts of northeastern China. Most Amur tigers are found in Russia, where their range is fragmented into at least 3 populations (a large population centered in the Sikhote-Alin Mountains and 2 smaller populations in northwest and southwest Primorye Krai). Traditionally, track-based techniques have been used for surveys of tigers in Russia. However, such techniques involve problems such as misinterpretation of track sizes due to snow degradation, and thus, other survey protocols have been needed. This study aimed to identify individuals and estimate population size using noninvasive genetic samples, such as feces, hairs, and saliva, collected from southwest Primorye Krai during 4 winters (2000–2001, 2001–2002, 2002–2003, and 2004–2005). During these winters, we identified 12 tigers (5 males and 7 females) using 10 microsatellite markers. Population size estimated from the 2002–2003 samples was 12 (95% confidence interval  =  9–19), which was comparable to the estimate from the track count survey. Of the 3 types of noninvasive genetic samples we collected, feces were the most useful in terms of genotyping success rate and sampling efficiency. The noninvasive genetic methods developed in this study can contribute to population monitoring and management assessment of tiger conservation in the Russian Far East.

The historical exclusion of fire from the longleaf pine–wiregrass (sandhills) ecosystem has resulted in a tremendous net loss of this important habitat. Prescribed fire is recognized as an essential tool for the maintenance of natural successional dynamics in this system, and its positive effects on native tree, shrub, and ground-layer plant communities are well documented. However, little is known about the influence of fire periodicity on many of the wildlife species occupying these forests. Our goal was to determine the relative degree to which a forest's structural characteristics and insect abundance and biomass influence the activity of different ecomorphological guilds of insectivorous bats and whether either of these factors was influenced by the periodicity of prescribed fire. We conducted a 2-year echolocation-monitoring study of bats in sandhills forests experiencing 3 categories of fire periodicity: 1–2 years, 3–5 years, and >8 years. We found significant differences in tree, shrub, and ground-layer characteristics among these burn-frequency categories, but few differences in abundance or biomass of most orders of nocturnal insects. However, the biomass of Lepidoptera was greatest at sites with the longest time between burns and was positively associated with fire-dependent deciduous tree and shrub densities. Bat activity below the canopy was significantly lower in the sites with >8-year burn frequencies than in either of the other treatments and was positively associated with height of canopy closure (a fire-dependent variable). Species-specific activity patterns confirmed ecomorphological predictions. Small-bodied species with low wing loadings and aspect ratios replaced larger, less-maneuverable species below the canopy at sites with >8-year burn frequencies. We provide support for the hypothesis that the structural characteristics of a habitat have primacy over prey availability in habitat choice by large and fast-flying species of bats. We suggest that frequency of fire is an important indirect determinant in structuring the communities of bats that forage in forests.

Estimators of home-range size require a large number of observations for estimation and sparse data typical of tropical studies often prohibit the use of such estimators. An alternative may be use of distance metrics as indexes of home range. However, tests of correlation between distance metrics and home-range estimators only exist for North American rodents. We evaluated the suitability of 3 distance metrics (mean distance between successive captures [SD], observed range length [ORL], and mean distance between all capture points [AD]) as indexes for home range for 2 Brazilian Atlantic forest rodents, Akodon montensis (montane grass mouse) and Delomys sublineatus (pallid Atlantic forest rat). Further, we investigated the robustness of distance metrics to low numbers of individuals and captures per individual. We observed a strong correlation between distance metrics and the home-range estimator. None of the metrics was influenced by the number of individuals. ORL presented a strong dependence on the number of captures per individual. Accuracy of SD and AD was not dependent on number of captures per individual, but precision of both metrics was low with numbers of captures below 10. We recommend the use of SD and AD instead of ORL and use of caution in interpretation of results based on trapping data with low captures per individual.

Searching for patchily distributed, highly localized, and seasonally variable resources in heterogeneous environments poses significant challenges for social species living in cohesive groups. Here, we studied the searching strategies of a highly social mammal, the white-lipped peccary (Tayassu pecari), in Calakmul Biosphere Reserve, Mexico. Calakmul Biosphere Reserve is a seasonal tropical forest where important resources, such as water and food, are patchy distributed and temporarily scarce. We attempted to determine what theoretical searching model best explained the movement patterns of groups of white-lipped peccaries, including short-tailed, long-tailed, and scale-free distributions. We found that the only distribution that was well supported by the data was a zero-inflated lognormal distribution; this implies a general pattern of normally short-range intensive searching with occasional long-distance directed movements taking the animals away from previously searched areas. We also found that groups concentrated foraging activities around sources of water during the dry season, behaving as central-place foragers while occasionally searching distant areas. We discuss the potential adaptive values of such behavioral strategies for social species living in highly heterogeneous environments.

Populations of the endemic and threatened marsupial Dromiciops gliroides were studied in logged and unlogged forest patches and shrublands in a rural area of northern Chiloé Island (42°S), Chile. We expected to find differences in abundance, with higher densities in unlogged, old-growth remnant forests. Individuals were livetrapped over 4 years (2005–2009) at the peak of their breeding (November) and nonbreeding (February) seasons. We estimated population densities using capture–mark–recapture procedures. Home range, diet (through fecal content), and health status (ectoparasite loads) were assessed for captured individuals. We estimated the length of the breeding season by the levels of reproductive hormones, whereas winter torpor was documented using artificial nest boxes. Population densities varied seasonally in accordance with breeding, with higher densities recorded during summer, and were similar in old-growth and in logged forests, but were considerable higher in forests than in shrublands. D. gliroides reproduced well in both unlogged and logged forests. Social torpor was documented for the 1st time and was fairly frequent (64%), especially among juveniles. Home ranges were 2 times larger for males than for females. We confirmed the omnivorous diet of D. gliroides, with predominant consumption of arthropods, and a higher consumption of fleshy fruits during summer. Habitat and animal age had significant effects on ectoparasite prevalence, with higher incidences among juveniles in logged forests. We conclude that D. gliroides is not a rare species in remnant forests in the rural landscape of Chiloé Island. This result is crucial for the assessment of its conservation status and offers clues for designing better conservation strategies for this living fossil in anthropogenic landscapes.

Food-storage behaviors can be plastic for food-hoarding species. Some hibernating, granivorous rodents switch seasonally from scatter hoarding (storing food in small, separate caches) to larder hoarding (concentrating food in a central location). To date, little is known about seasonal food-hoarding behaviors of free-living rodents that forage and store food year-round (i.e., nonhibernators). Using direct observations, radiotelemetry, and tracking with fluorescent powder, we discovered a striking seasonal shift in food-hoarding behaviors for Ord's kangaroo rat (Dipodomys ordii), a nonhibernating rodent in a region with dramatic seasonal climate (i.e., the Great Plains of the United States). In winter, D. ordii almost exclusively larder hoarded seeds in burrows and used a single burrow, which is consistent with the larder-defensibility hypothesis of food storage. The lack of suitable sites to scatter hoard due to snow cover and frozen soils likely contributed to larder hoarding in winter. In summer, most individuals scatter hoarded near seed sources, which is consistent with the rapid-sequestering hypothesis of food storage. In summer, individuals also commonly used multiple burrows, and differences in food-hoarding and burrow-use behavior were observed between sexes and between reproductively active and inactive females. By scatter hoarding and using multiple burrows in summer, kangaroo rats likely reduce costs associated with defending larder hoards while increasing benefits associated with reproduction. The seasonal interplay between food hoarding and burrow use by D. ordii appears to be important for securing and maintaining resources throughout the year in a temperate environment.

Understanding how environmental factors affect activity, number, and spatial distribution of bats in an area is necessary for interpreting capture rates and assessing abundance. Over a 34-year period, we examined the relationship between amounts of precipitation and activity of bats along a canyon floor in the San Mateo Mountains of New Mexico in the southwestern United States. For 1 night during each of 19 summers, we used identical sampling techniques to monitor this assemblage of insectivorous bats. Years included droughts with minimal surface water and wet years with abundant surface water in the canyon. Marked differences in available drinking water resulted in striking differences in yearly captures of bats, with a 30.8-fold difference between the fewest and most captures (6 versus 185 adults). Capture rates increased with less precipitation before sampling. In the 3-decadal period, precipitation accounted for 66% of the variation in capture rates, providing support that bats concentrate around accessible water to drink when surface water is scarce. Captures also were influenced by relative humidity on nights of sampling. From 1971 to 2005, we detected no change in species composition in this bat assemblage of 8 species, and after accounting for effects of precipitation, we detected no declines in population size for the 2 most common species, the long-eared myotis (Myotis evotis) and long-legged myotis (M. volans). Our study demonstrates the importance of long-term data sets to help elucidate patterns of variability in capture data and highlights the importance of how yearly variation in climate affects the behavior and ecology of bats.

Animals interact with their environment at multiple spatial, temporal, and behavioral scales. Few studies of selection for latrine sites by river otters (Lontra canadensis) have considered spatial scale, and no studies have integrated scales of behavior. We used an information theoretic model comparison approach to identify elements of otter habitat that influence the presence, consistency, and intensity of latrine-site activity at 2 spatial scales. We identified and monitored 73 latrine sites in central British Columbia, Canada, during the open-water season in 2007 and 2008. We inventoried latrines and randomly selected sites along the adjacent shoreline, and used those data in the form of a binary resource selection function to model fine-scale selection of latrine sites. At the scale of the landscape, we used a resource selection function and data from geographic information systems to model coarse-scale selection of latrine sites. Drawing on those same data, we used binary and count models to quantify factors that contributed to the consistency (high versus low use) and intensity (number of scats) of otter activity at latrine sites. Fine-scale habitat characteristics were better at predicting the presence of latrine sites when compared to coarse-scale geographic information system data. In general, the presence, consistency, and intensity of latrine activity at the fine scale were influenced by visual obscurity, larger trees, and characteristics of conifer trees. The presence of latrine sites at the coarse scale could not be accurately described by any of the models. The consistency and intensity of activity of otters at latrine sites at the coarse scale, however, was best predicted by habitat characteristics beneficial to fish. These results provide insight into the spatial and behavioral scales of latrine-site activity by river otters that can be incorporated into management, monitoring, and conservation strategies.

Data collected over the past 15 years in Colorado show that deer mice (Peromyscus maniculatus) collected in southeastern Colorado have a significantly lower Sin Nombre virus (SNV) antibody prevalence than mice from western Colorado. Based on mitochondrial sequences, P. maniculatus was recently subdivided into 6 clades. Clade 1a occurs throughout the mountainous regions of western Colorado and clade 2 crosses the short-grass steppe in southeastern Colorado. We used mitochondrial single nucleotide polymorphisms (SNPs) from this earlier study and 14 nuclear SNPs to test the hypothesis that clade 2 mice consist of a separate subspecies. Little genetic differentiation was detected (F_ST  =  0.027) among 435 deer mice collected from 8 locations in western Colorado. In contrast, 171 deer mice collected from 4 locations in eastern Colorado were genetically differentiated from one another (F_ST  =  0.168) and from those captured in western Colorado (F_ST  =  0.256). During this survey we identified a single locality in central Colorado where both clade 1a and 2 mice are sympatric and have a high SNV seropositivity (52.2% in 2006; 24.4% in 2009). Antibody prevalence was 21.1% among clade 2 mice, lower than the 32.4% rate among clade 1a mice, suggesting that clade 2 mice may, for both genetic and environmental reasons, have lower susceptibility to SNV infection.

Aquatic foraging is a fundamental component of the behavior of a number of small mammals, yet comprehensive observations of diving are often difficult to obtain under natural circumstances. Semiaquatic mammals, having evolved to exploit prey in both aquatic and terrestrial environments, are generally not as well adapted for diving (or for life in the water) as are fully aquatic species. Because dive ability also tends to increase with body size, small, semiaquatic mammals are presumed to have fairly limited dive ability. Nevertheless, diving plays an important role in food acquisition for many such species. We used time–depth recorders (TDRs) to measure and describe the dive performance of 9 female and 5 male free-living American mink (Neovison vison; body mass approximately 1 kg) on lowland rivers in the southern United Kingdom. We recorded dives up to 2.96 m deep (maximum depth X¯  =  1.82 m) and up to 57.9 s in duration (maximum duration X¯  =  37.2 s). Dive duration was approximately 40% of that predicted by allometry for all air-breathing diving vertebrates (as might be expected for a small, semiaquatic animal) but was twice as long as previously measured for mink in captivity. Mink performed up to 189 dives per day (X¯  =  35.7 dives/day), mostly during daylight, and spent a maximum of 38.4 minutes diving per day (X¯  =  7.6 min/day). Some individuals maintained particularly high diving rates over the coldest months, suggesting that the benefits of aquatic foraging in winter outweigh the costs of heat loss. We observed a number of very shallow dives (depth approximately 0.3 m) of particularly long duration (up to 30 s). The function of these dives is currently unknown, but possibilities include searching for prey, travelling, or avoidance of threats. There is only 1 other study of which we are aware that presents detailed measurements of dive performance in a small, shallow-diving, semiaquatic mammal.

Many species of wild mammals occur in habitats that have been disturbed by fragmentation or degraded in quality. Previous researchers have hypothesized that demographic characteristics of populations may shift with changes in environmental conditions, with self-regulatory ability increasing with environmental suitability. We studied responses of white-footed mice (Peromyscus leucopus) to habitat disturbance. Given that optimal habitat for this species is deciduous woodland, we predicted that populations in habitats disturbed by cutting woody vegetation would be lower and more variable in density than in undisturbed habitat, density and stability of populations in disturbed habitat would increase over time, survival would be higher in undisturbed than in disturbed habitat, and populations in undisturbed habitat would show a greater degree of self-regulation. This 6-year study in western Pennsylvania involved 3 replicated study sites (each 3.8 ha), with woody vegetation removed on half of each site prior to beginning the study. Density in disturbed treatment averaged 65% of density in undisturbed habitat. There were no differences between treatments in survival or in population growth rates over time. Population trends over time were similar between treatments, populations in disturbed habitat did not become more stable with time, and density did not converge with that of undisturbed habitat. Although populations in the undisturbed habitat were clearly self-regulating, those in disturbed habitats were not. Despite expectations that demographic performance will align with environmental suitability, it may be difficult to ascribe a particular demography to a habitat generalist such as P. leucopus.

The 60-g subtropical Formosan leaf-nosed bat, Hipposideros terasensis, hibernates in the wild at warm roost (and hence body) temperatures up to 23°C. For small hibernators, torpid metabolic rate is temperature dependent and thus hibernation in warm hibernacula is predicted to be energetically costly. This species, however, rarely feeds during the hibernation season to offset the expected high energetic costs. In this study we used a respirometry system to quantify physiological characteristics of euthermic and torpid H. terasensis in winter. We tested the hypothesis that H. terasensis exhibits metabolic inhibition during torpor. Our results showed that H. terasensis saved 94.6% energy by using torpor at air temperatures of 15°C, compared with its euthermic metabolic rate at that air temperature. Torpor metabolic rate declined with declining air temperature to around 14°C, but then increased at lower air temperatures of 10–14°C. Above 14°C , the slope of −13.0°K ± 1.4°K between metabolic rates and body temperatures in an Arrhenius plot (or Q₁₀  =  4.4) suggests that, in addition to direct temperature effects, H. terasensis exhibited metabolic inhibition during torpor. A model used to evaluate energy expenditure of H. terasensis showed that at 20°C and 23°C a 55-g bat needs 194 kJ (4.9 g fat) and 273.2 kJ (6.9 g fat), respectively, to survive a 70-day hibernation period.

Within socially monogamous species, a male's reproductive success depends on his success at obtaining a social partner with which he mates, as well as gaining extra-pair matings. We investigated the impacts of body mass and parasitism on 2 measures of a male's success at obtaining a social partner (number of female social associations and relative strength of a social bond to a single female) and 2 measures of reproduction (number of females with which a male sires offspring and the number of offspring sired) in natural populations of prairie voles (Microtus ochrogaster) located in Kansas and Indiana. Kansas males with greater endoparasite loads were less likely to have one social partner. Instead, they associated with multiple females although they did not sire offspring with more females than males with lower levels of endoparasitism. We did not find any relationship between endoparasite infestation and the number of females with which males associated in Indiana. There was no association between the level of endoparasites found among males in either Indiana or Kansas and the strength of a male's social bond to a female. Endoparasites, at least at the infection levels detected in this study, were not related to indices of male reproductive success in Microtus populations in Kansas or Indiana. No relationship was found between body mass and indicators of social monogamy in either population. However, body mass appears to be significantly related to male reproductive success. Heavier males produced offspring with more females, particularly in the Kansas population, and sired more pups in both populations.

The formation and maintenance of alliances is regarded as one of the most socially complex male mating strategies in mammals. The prevalence and complexity of these cooperative relationships, however, varies considerably among species as well as within and between populations living in different ecological and social environments. We assessed patterns of alliance formation for Indo-Pacific bottlenose dolphins, Tursiops aduncus, in Port Stephens, New South Wales, Australia, to investigate the stability of these alliances, the structure of associations, as well as variation in schooling patterns among males. Our results showed that association patterns among males within this population showed considerable variability. Males either formed strong and enduring alliances that lasted for at least 8 years with minimal partner switching, or less stable partnerships within a much larger male social network. Male alliances with the strongest levels of association within a given time period were significantly more likely to maintain their relationships over the long term compared with alliances with lower levels of association. Males in stable alliances also associated in significantly smaller schools than males who formed less stable alliance partnerships. Finally, we found that alliances consisting of more related males did not persist longer than alliances between unrelated individuals. Our study suggests that intrapopulation variation in male alliance formation in dolphins likely reflects different mating strategies adopted as individual responses to their complex fission–fusion social environment.

The role of environmental limitation and density-dependent regulation in shaping populations is debated in ecology. Populations at low densities may offer an unobstructed view of basic environmental and physiological interactions that impact individual fitness and thus population productivity. The energy reserves of an organism are reflected in its body condition, a measure linking individual fitness and the environment. From 1997 to 2007, we monitored the critically endangered western gray whale (Eschrichtius robustus) population on its primary summer feeding ground off the northeastern coast of Sakhalin Island, Russia. This effort resulted in a large data set of photo-identification images from 5,007 sightings of 168 individual whales that we used to visually assess western gray whale body condition. We quantified temporal variation in the resulting 1,539 monthly body condition determinations with respect to observations of reproductive status and sex. Western gray whale body condition varied annually, and we identified years of significantly better (2004) and worse (1999, 2006, and 2007) body condition. This study is the 1st to track the within-season body condition of individual whales. Body condition improved significantly as the summer progressed, although results suggest that not all whales replenish their energy stores by the end of the season. The body condition of lactating females was significantly worse than that of other whales at all times and was most often determined to be compromised. The body condition of their weaning calves exhibited no temporal variation and was consistently good. It is possible lactating females provide an energetic buffer to their offspring at the expense of their own body condition and future reproductive success. Findings from the analysis establish a foundation for quantifying links between western gray whale body condition, demographic parameters, and environmental conditions; and provide a baseline for monitoring individual and population condition of an ecosystem sentinel species in a changing environment. Overall, this study highlights the presence of density-independent environmental and physiological mechanisms that affect the abundance and growth of populations.

We related temporal variation in the environment to demographic parameters and body condition of ringed seals (Phoca hispida) in Hudson Bay, near the southern limit of the species' geographic range. Ringed seals harvested by Inuit hunters for subsistence purposes in Arviat, Nunavut, Canada, from 1991 to 2006 were measured and sampled. Ringed seal ovulation rate did not change over time, but pregnancy rate and percent pups in the fall harvest increased in the 2000s, compared to the 1990s. Ringed seals grew faster and attained sexual maturity earlier in life, and the population age structure shifted to younger age classes in the 2000s compared to the 1990s. Ringed seal demographic parameters were characteristic of a population in decline in the 1990s and a growing population in the 2000s. A quadratic polynomial regression best described the relationship between percent pups in the harvest and snow depth, and between pup and adult female body condition index and date of spring breakup, suggesting that ringed seals have evolved to do best within a relatively limited range of environmental conditions. We propose that the decline of ringed seal reproductive parameters and pup survival in the 1990s could have been triggered by unusually cold winters and heavy ice conditions that prevailed in Hudson Bay in the early 1990s, through nutritional stress and increased predation pressure. The recovery in the 2000s may have been augmented by immigration of pups, juveniles, and young adult ringed seals into the study area. We discuss the possibility of a decadal-scale biological cycle that reflects fluctuations in climatic variables, and particularly in the sea ice regime.

Assessing the relative importance of environmental and anthropogenic influences on the distribution of wild populations is an important step in designing spatially explicit plans for their management and protection. We examined environmental variables correlated with the spatial distribution of eastern Pacific harbor seals (Phoca vitulina richardii), a marine mammal common to coastal waters, in a large, highly urbanized estuary. We assessed the relationship between prey abundance, depth, bottom relief, proximity to terrestrial haul-out sites and 3 potential sources of anthropogenic influence, and the in-water spatial distribution of seals. We identified locations of seals using satellite-linked telemetry, and used partial Mantel tests to assess which environmental variables were most strongly linked to seal foraging distribution, given spatial autocorrelation within variables. Mann–Whitney tests were used to compare environmental characteristics of locations of seals with a random distribution of locations. Because harbor seals are central-place foragers, we incorporated spatial distribution of seals relative to the central place into our analyses. High prey abundance and proximity to the haul-out site were strongly associated with the spatial distribution of seals. Harbor seals also tended to use deeper waters and areas of high bottom relief within the estuary. There was no consistent spatial relationship between the 3 anthropogenic factors and the distribution of seals, although seals tended to be found closer than expected to sites of high human activity. In highly impacted coastal areas where limited alternate suitable habitat exists, foraging seals may need to rely on disturbed (suboptimal) areas, and as a result may habituate to human presence in areas rich in food resources.