Search

Long-distance movements (LDMs) of small mammals (SMs) are complex phenomena that cover both dispersals and excursions occurring outside the home ranges of individuals. Owing to methodological difficulties, there are a lack of data on LDMs for SMs. In this study, we aimed to determine the factors that influence the LDMs of different mouse-sized rodents and shrews in the Ural taiga (Sverdlovsk region, Russia). We conducted a field experiment in a boreal forest using individual- (capture–marking–recapture [CMR]) and group- (biomarkers: tetracycline and rhodamine B) marking methods, in conjunction with additional feeding. The species, sex, maturity, plot ID, additional food supply, species abundance indices, individuals/100 trap-nights indices in the capture plot, and body weight of each animal were analyzed as predictors of LDMs. We identified 89 individuals from six species that moved at distances of 250, 350, and 500 m. LDMs varied with the particular species and its population abundance. Most of the observed movements were excursions and not dispersal events. Applying mathematical simulations to the obtained empirical data facilitated estimation of the intensity of the excursion activity for different species. We present the 1st excursion data on Sylvaemus uralensis (Pallas, 1811), Microtus arvalis (Pallas, 1778), and Sorex caecutiens (Laxmann, 1788). The detected excursion distance (250 m) for Myodes glareolus (Schreber, 1780) is the maximum excursion distance known for this species. We demonstrate that with comparable labor and time costs, the use of biomarkers makes it possible to detect many more LDMs than CMR allows. [ABSTRACT FROM AUTHOR]

Space use by mammals can differ among age-classes, sexes, or seasons, and these processes are recognized as adaptive behavioral strategies. Semi-fossorial ground squirrels, in particular, have shown age- and sex-specific patterns in their aboveground movement behaviors. We studied space use of Mohave ground squirrels (Xerospermophilus mohavensis) at the Freeman Gulch study site in the central region of their range in the Mojave Desert, California. We documented the timing of their full annual cycle, investigated correlates of size of home ranges of adults and distance of long-distance movements by juveniles, and evaluated whether juvenile body masses and movements were related to interannual climatic variation. Adult males emerged from burrows and entered hibernation sooner than did adult females. Home ranges were larger for males (⁠ x ¯ ± SD = 0.50 ± 0.40 km2) than females (0.05 ± 0.03 km2), especially during the mating season. Maximum distances moved by juveniles did not differ significantly between males (1.6 ± 2.3 km) and females (1.0 ± 1.8 km), and both sexes were equally likely to travel long distances from natal sites. The longest-distance movement we documented was 7.7 km by a juvenile male. Juveniles born in a year of low vegetation productivity gained significantly less mass (97 ± 7 g) and traveled shorter distances than those born in a year of higher vegetation productivity (177 ± 20 g). Our findings were similar to those documented in the Coso Range study site in the northern region of the geographic range of the species, indicating that movement patterns are similar range-wide. Mohave ground squirrels responded strongly to climate variation, and global climate change will likely result in a northward shift in suitable habitats. Informed conservation planning, therefore, will be essential for this rare, declining species. [ABSTRACT FROM AUTHOR]

The effects of conspecific densities on dispersal have been well documented. However, while positive and negative density-dependent dispersal based on conspecific densities often are shown to be the result of intraspecific competition or facilitation, respectively, the effects of heterospecific densities on dispersal have been examined far less frequently. This gap in knowledge warrants investigation given the potential for the analogous processes of interspecific competition and heterospecific attraction to influence dispersal patterns and behavior. Here we use a long-term live-trapping study of deer mouse (Peromyscus maniculatus), eastern chipmunk (Tamias striatus), red-backed vole (Myodes gapperi), and jumping mice (Napaeozapus insignis and Zapus hudsonius) to examine the effects of variation in conspecific and heterospecific abundances on dispersal frequency. In terms of conspecific abundance, jumping mice were more likely to disperse from areas with fewer conspecifics, while red-backed voles and chipmunks did not respond to variation in conspecific abundances in their dispersal frequencies. While there were no statistically significant effects of variation in heterospecific abundances on dispersal frequency, some effect sizes for heterospecific abundance effects on dispersal met or exceeded those of conspecific abundances. Conspecific abundances clearly can affect dispersal by some species in this system, but the effects of heterospecific abundances on dispersal frequency are less clear. Based on effect sizes, it appears that there may be potential for heterospecific effects on dispersal by some species in the community, although the strength and causes of these relationships remain unclear. [ABSTRACT FROM AUTHOR]

Geomagnetic sensitivity is present in a variety of vertebrates, but only recently has attention focused on subterranean mammals. We report the potential use of a magnetic compass in wild Damaraland mole-rats (Fukomys damarensis) during dispersal at two sites in the Kalahari region of South Africa. When the distance traveled was greater than 250 m, males and females dispersed in opposite directions and females preferentially chose a predominantly northeastern direction. This directional choice likely is due to the differing dispersal tactics between sexes. This evidence suggests that Damaraland mole-rats employ a magnetic compass during aboveground dispersal to assist in locating mates or a new territory. This study provides evidence to show how magnetic compass use could be useful in dispersal, an important ecological process for mammals. [ABSTRACT FROM AUTHOR]

Steller sea lions (Eumetopias jubatus) are composed of two genetically distinct metapopulations (an increasing "eastern" and a reduced and endangered "western" population, or stock for management purposes in U.S. waters) that are only recently mixing at new rookeries in northern Southeast Alaska, east of the current stock boundary. We used mark-recapture models and 18 years of resighting data of over 3,500 individuals marked at the new rookeries and at neighboring long-established rookeries in both populations to examine morphology, survival, and movement patterns of pups born at new rookeries based on whether they had mitochondrial DNA haplotypes from the western or eastern population (mtW or mtE); examine survival effects of dispersal to the Eastern Stock region for animals born in the Western Stock region; and estimate minimum proportions of animals with western genetic material in regions within Southeast Alaska. Pups born at new rookeries with mtW had similar mass, but reduced body condition and first-year survival (approximately –10%) compared to pups with mtE. mtE pups ranged more widely than mtW pups, including more to the sheltered waters of Southeast Alaska's Inside Passage. Fitness benefits for western-born females that dispersed to Southeast Alaska were observed as higher female survival (+0.127, +0.099, and +0.032 at ages 1, 2, and 3+) and higher survival of their female offspring to breeding age (+0.15) compared to females that remained west of the boundary. We estimated that a minimum of 38% and 13% of animals in the North Outer Coast–Glacier Bay and Lynn Canal–Frederick Sound regions in Southeast Alaska, respectively, carry genetic information unique to the western population. Despite fitness benefits to western females that dispersed east, asymmetric dispersal costs or other genetic or maternal effects may limit the growth of the western genetic lineage at the new rookeries, and these factors require further study. [ABSTRACT FROM AUTHOR]

Steller sea lions (Eumetopias jubatus) are composed of two genetically distinct metapopulations (an increasing "eastern" and a reduced and endangered "western" population, or stock for management purposes in U.S. waters) that are only recently mixing at new rookeries in northern Southeast Alaska, east of the current stock boundary. We used mark-recapture models and 18 years of resighting data of over 3,500 individuals marked at the new rookeries and at neighboring long-established rookeries in both populations to examine morphology, survival, and movement patterns of pups born at new rookeries based on whether they had mitochondrial DNA haplotypes from the western or eastern population (mtW or mtE); examine survival effects of dispersal to the Eastern Stock region for animals born in the Western Stock region; and estimate minimum proportions of animals with western genetic material in regions within Southeast Alaska. Pups born at new rookeries with mtW had similar mass, but reduced body condition and first-year survival (approximately −10%) compared to pups with mtE. mtE pups ranged more widely than mtW pups, including more to the sheltered waters of Southeast Alaska's Inside Passage. Fitness benefits for western-born females that dispersed to Southeast Alaska were observed as higher female survival (+0.127, +0.099, and +0.032 at ages 1, 2, and 3+) and higher survival of their female offspring to breeding age (+0.15) compared to females that remained west of the boundary. We estimated that a minimum of 38% and 13% of animals in the North Outer Coast–Glacier Bay and Lynn Canal–Frederick Sound regions in Southeast Alaska, respectively, carry genetic information unique to the western population. Despite fitness benefits to western females that dispersed east, asymmetric dispersal costs or other genetic or maternal effects may limit the growth of the western genetic lineage at the new rookeries, and these factors require further study. [ABSTRACT FROM AUTHOR]

Movement ecology and dispersal capabilities inherently drive genetic structure across landscapes. Through understanding dispersal and gene flow of giant kangaroo rats (Dipodomys ingens), conservation efforts can be focused, and we can further understand how genetic structure persists in this highly endemic small mammal. Here, we genetically identify parent–offspring and sibship relationships among 239 giant kangaroo rats using 15 microsatellites in the northern part of the species range and describe the individual genetic-spatial variation using a Moran eigenvector map (MEM). We further employ two landscape genetic analyses (isolation by resistance [IBR] and least cost paths [LCPs]) and two individual-based genetic metrics (Dps and a codominant marker distance from GenAlEx) to determine landscape factors (precipitation, slope, vegetation community, and roads) that influence gene flow. We found 19 pairs of related individuals, of which 18 were less than 250 m apart, but one sibling pair was 5.52 km apart, suggesting greater dispersal capabilities than previously noted. We found hierarchal spatial genetic structure using a MEM, with 3–4 genetically similar regions and two genetically similar subregions. Finally, we found low correlative strength between landscape features and gene flow. IBR consistently outperformed LCPs, and there was evidence that regions with 250–350 mm of precipitation and slope ≤ 5° promoted connectivity. We recommend that managers focus on habitat protection rather than corridor maintenance, with the caveat that anthropogenic factors were minimally considered in this study. [ABSTRACT FROM AUTHOR]

We determined patterns of burrow use by juvenile platypuses (Ornithorhynchus anatinus) in their natal home range, and evaluated associations between burrows and vegetation. Between March 2015 and March 2017, we captured seven juvenile platypuses along a 3-km stretch of Badger Creek, Victoria and fitted them with radiotransmitters. We recorded the locations of animals in their burrows daily while transmitters were attached (range: 14–132 days). Juveniles used 74 different burrows, with each using 11 ± 2 burrows. Overall, 65% of burrows (48) were used once, 22% (16) were used between 2 and 9 times (moderate-use), and 13% (10) were used frequently (> 10 times). No juveniles dispersed during the monitoring period (14–132 days). Although some association was observed between burrow use and particular vegetation communities, vegetation was not a strong factor driving site selection of burrows. Use of multiple burrows may allow juveniles to avoid competition with conspecifics, reduce exposure to ectoparasites, and develop shelter-seeking behavior. Juvenile platypuses remained in their natal home range, where conditions are likely to be good because they supported recent breeding, while completing their growth and development prior to dispersal. [ABSTRACT FROM AUTHOR]

Natal dispersal likely plays an important role in avoiding inbreeding among large carnivores. We tested the hypothesis that male-biased dispersal reduces close inbreeding by limiting the spatial overlap of opposite-sex pairs of close relatives in brown bears (Ursus arctos) in the Shiretoko Peninsula, Hokkaido, Japan. We genotyped 837 individuals collected in 1998–2017 at 21 microsatellite loci and performed parentage analysis. To calculate natal dispersal distance, we considered the site where the mother was identified as the birthplace of her offspring, and the site where the offspring were identified as their dispersed place. As predicted, we found that dispersal distances were significantly greater for males (12.4 km ± 1.0) than for females (7.7 km ± 0.9), and those for males increased from 3 years old, indicating that males begin to disperse around the time sexual maturation begins. Relatedness decreased with distance among pairs of females, and the mean relatedness was significantly higher between pairs of females than between pairs of males or between female–male pairs within 3 km. Closely related female–male pairs rarely (5–6%) resided in close proximity (< 3 km), compared with pairs of closely related females. Our study revealed that the potential for close inbreeding was low in Hokkaido brown bears because males are effective dispersers. [ABSTRACT FROM AUTHOR]

Townsend's big-eared bat (Corynorhinus townsendii townsendii) is a wide-ranging subspecies found throughout the western United States. Of the 5 subspecies currently recognized within C. townsendii, 2 are federally endangered and 2 others are considered species of concern. In California, C. t. townsendii is a species of concern given its loss of habitat and presumed limited dispersal capabilities. Here, we investigated the genetic structure and diversity of a group of maternity colonies across the Inyo-White Mountains in west-central California. Analysis of both nuclear (microsatellite loci) and mitochondrial (D-loop fragment) data show a lack of structure across the study region and significant isolation-by-distance, supporting gene flow among maternity colonies in a stepping stone pattern. The maternity colonies in our sampling region are thus part of 1 genetically healthy, panmictic population. Despite the overall genetic viability of C. t. townsendii in this region, we suggest maintaining the connection between colonies is a crucial step in the management and persistence of the subspecies. [ABSTRACT FROM AUTHOR]

Brazilian free-tailed bats (Tadarida brasiliensis) are one of the most widely distributed bat species in the Americas, often engaging in rapid, long-distance dispersals. Here, we document that, since ca. 2007, these bats have expanded their range into western North Carolina, eastern Tennessee and Virginia. Reports from wildlife control professionals, wildlife rehabilitators, regional submissions of bats for rabies testing, acoustic monitoring and the presence of T. brasiliensis in buildings and bat houses indicate that these bats are now established in year-round colonies in areas previously thought outside their range limits. The geographic distributions of many organisms are currently shifting to higher latitudes in response to changing climate. We hypothesize that a coldtolerant thermal physiology that allows these largely tropical bats to enter extended torpor contributes to the ability of T. brasiliensis to establish populations in formerly cooler regions and propose that their rapid northward expansion is facilitated by climate change and their tendency to explore new habitats and use a wide diversity of roost sites. Because of their abundance and use of man-made structures, we anticipate that the range expansion of T. brasiliensis will have implications for public health, ecosystem services and bat conservation. [ABSTRACT FROM AUTHOR]

Intraspecific variation in ranging and social behavior can be perplexing, but also provides an opportunity to assess which behavioral attributes are labile in the face of geographic variation in resources. White-nosed coatis (Nasua narica) are group-living carnivores of tropical origin that possess an unusual social system. In the resourcerich tropics, larger-bodied males are solitary, whereas females live in groups ("bands") along with young of both sexes, but leave them to give birth and wean their young. Males often disperse socially, but not spatially. We studied coatis in the Chiricahua National Monument, Arizona, a resource-poor, arid, and highly seasonal landscape. Using live capture and radiotelemetry in conjunction with microsatellite DNA analyses, we found that Chiricahua coatis exhibited the species-typical pattern of solitary males and gregarious females. Young males left their natal bands as yearlings, and some were found as adults within their natal home range. On the other hand, home ranges were expanded greatly. Bands, and some males, focused their movements in areas several km2 in extent over periods of weeks or months but shifted those areas markedly among seasons. Some males followed the typical mammalian pattern of natal dispersal beyond their natal area. Rates of movement were higher and female associations appeared to be more flexible than in the tropics. Adult females sometimes ranged singly, not only around the time of parturition, but also when population density was low and occasionally otherwise. In addition, home range overlap was high among both sexes during some seasons, and female bands sometimes fused for prolonged periods. Core patterns of sociality are constant in both resource-rich tropical and resourcepoor temperate populations, but coatis appear to make major adjustments in scale of movement and frequency of association in response to resource variation. [ABSTRACT FROM AUTHOR]

A history of timber harvest in West Virginia has reduced red spruce (Picea rubens) forests to < 10% of their historic range and resulted in considerable habitat fragmentation for wildlife species associated with these forests. The Virginia northern flying squirrel (Glaucomys sabrinus fuscus) has been described as a red spruce obligate subspecies that must traverse this fragmented landscape to disperse among remnant red spruce patches. Food availability in the forest matrix surrounding red spruce may be a limiting factor to successful dispersal of G. s. fuscus. We examined the diet of flying squirrels using stable isotope analysis and used vegetation surveys to determine the availability of diet items in the habitats encountered by G. s. fuscus in the matrix surrounding red spruce fragments. Stable isotope analysis suggested hypogeous fungi, epigeous fungi, and invertebrates contributed the most to the diet of G. s. fuscus, followed by lichen. Tree buds contributed the least in spring, and beechnuts contributed the least in fall. The vegetation surveys revealed that no habitat type had a greater availability of the diet items that contributed most to the assimilated diet of G. s. fuscus, suggesting that stand age and structure may be more important for diet-item availability than habitat type. [ABSTRACT FROM AUTHOR]

Bat-eared foxes (Otocyon megalotis) are the primary vector and maintenance host species for rabies in the western half of South Africa. Reported cases of rabies in this species peak during the dry season, although reasons for this annual peak are unknown. Rabies transmission is dependent on contact rates, thus seasonal differences in social behavior or movements may facilitate increased contact rates in the dry season. During an ecological study of bat-eared foxes in South Africa from 2005 to 2008, we compared between the wet and dry seasons several aspects of the ecology of bat-eared foxes that presumably would influence contact rates. Bat-eared foxes had significantly larger group sizes in the dry season, which would presumably increase intragroup contact rates, and significantly greater home-range sizes, greater home-range overlap and higher rates of excursions (i.e., short-term forays from their home range), which would presumably increase intergroup contact rates. Seasonal differences in behavior and movements of bat-eared foxes likely were related to their reproductive cycle and seasonal availability of food resources. In contrast to previous reports, we documented relatively high rates of physical contact between bateared foxes and dogs (Canis familiaris) and black-backed jackals (C. mesomelas), suggesting there is potential for bat-eared foxes to transmit the rabies virus to larger canids in the region. We provide recommendations for control of rabies outbreaks in bat-eared foxes if it becomes a health or management concern. [ABSTRACT FROM AUTHOR]

The raccoon (Procyon lotor) is an ecologically important mesopredator that threatens at least 11 species of beach-nesting and colonial waterbirds on the Virginia barrier islands. An understanding of population dynamics, reproductive sources and sinks, and dispersal pathways among the islands and the adjacent Delmarva Peninsula mainland will help prioritize allocation of scarce resources for managing these raccoon populations. We characterized these metapopulation processes by examining variation across mitochondrial (mtDNA) and nuclear DNA (microsatellite) markers. We sequenced a 515-base pair fragment of mtDNA (containing the 5'-end of the cytochrome-b gene, the 3'-end of the D-loop, and the intervening tRNA genes) in 164 animals from 22 localities. We detected 7 unique mtDNA sequences, distributed along a presumably long-term, north-south genetic gradient on the islands and on the mainland, reflecting the temporal sequence of colonization of these areas. We also genotyped 13 nuclear microsatellite loci in 314 individuals from 24 localities, and we found complex patterns of spatial population structure, dispersal, and gene flow among island and mainland localities. Whereas mainland localities showed considerable admixture, suggesting multiple waves of colonization, most islands showed little admixture, suggesting single founding events and relative isolation since founding. Islands formed 2 genetically cohesive groups, 1 in the north and another in the south. Based on patterns of genetic variation, estimates of effective population size, and immigration-emigration rates, Parramore and Revel islands serve as the major demographic source of raccoons on the northern islands, whereas Smith Island is the major source of raccoons on the southern islands. Most inferred movements of raccoons occurred among adjacent groups of islands that are interconnected by marsh and relatively shallow, narrow, open-water channels. These genetic results are consistent with our empirical studies of raccoon movement and support predictions from a cost-distance model of raccoon movement, which assumes that gene flow is primarily constrained by a combination of spatial distance and landscape resistance. Our landscape genetic analyses indicated that: 1) raccoons occur in a series of semi-independent local populations that exhibit significant genetic structure and are characterized by historical and ongoing colonization events, 2) island populations exhibit evidence of source-sink dynamics in patterns of variation in genetic diversity, effective population size, and emigration-immigration rates, 3) the Delmarva Peninsula mainland is not a major source of raccoons dispersing to most of the islands, and 4) individuals dispersed mostly among nearby islands and along least-cost pathways of landscape resistance, in agreement with predictions based on cost-distance models of raccoon movement in this system. [ABSTRACT FROM AUTHOR]

Agricultural ecosystems are spatially and temporally dynamic systems that support wildlife populations in addition to food production for humans. The composition and configuration of land cover within agricultural systems, which often varies seasonally or annually, can have profound impacts on biodiversity. Specifically, landscape structure can influence animal dispersal and distribution. Depending on species-specific ecology, dispersal may be restricted, resulting in smaller, reproductively isolated populations. Few studies have characterized the spatial genetic structure of small mammal species in agricultural landscapes, despite their importance to crop pest management and food webs within agroecosystems. We characterized the spatial genetic structure of 2 co-distributed Peromyscus species (Peromyscus leucopus and Peromyscus maniculatus bairdii), and quantified relationships between spatial genetic structure based on interindividual relatedness resolved from 10 microsatellite loci, and landscape features hypothesized to influence dispersal. We found significant spatial autocorrelation in interindividual relatedness over interindividual distances of 1,800 m for P. leucopus and 300 m for P. maniculatus bairdii. We also identified distinct genetic clusters of interbreeding individuals for both species. Spatial genetic structure of P. leucopus was significantly related to the distribution of roads, indicating that highly fragmented landscapes could negatively affect dispersal and gene flow. Given the large and growing footprint of agriculture globally, it is important that studies of the effects that landscape features have on dispersal of wildlife species include human-dominated landscapes. [ABSTRACT FROM AUTHOR]

Exposure of individuals to novel environmental conditions generally favors locally adapted phenotypes and can influence the likelihood of successful dispersal or the success of translocation efforts. We used geometric morphometrics to characterize American marten (Martes americana) skull morphology for descendants of animals reintroduced to the Upper Peninsula of Michigan, USA (~44,000 km2) from genetically distinct source populations. Using univariate and multivariate analyses, we quantified associations between interindividual variation in skull shape and size, genealogical relationships, past introduction history, local harvest density of competitors, and contemporary landscape features we hypothesized would be related to diet. Effects of other sources of variation including shared ancestry (source population, geographic distance, and coancestry among descendants), sex, and age were also evaluated. Descendant skull shape was related to progenitor source population, sex, and age. In contrast to strong associations between spatial genetic structure based on neutral molecular markers and measures of landscape effects on dispersal, variation in skull shape among descendants was not associated with geographic distance or landscape features. Our study addressed a critical issue regarding a widely used conservation prescription. Specifically, when individuals are transplanted to reestablish extirpated species, do their descendants retain the features of the source population(s), or do they adapt to local conditions? Marten skull shape following reintroduction events is most likely determined by a combination of differences in morphology of source populations and geographic variation in habitat, rather than being influenced by a single factor. [ABSTRACT FROM AUTHOR]

Studies about habitat fragmentation, in terms of how it affects gene flow and genetic variability, have traditionally been conducted on island-like systems in which the remaining habitats form patches embedded in a matrix. However, in agroecosystems, remaining habitats usually form linear strips along fence lines, roads, and water courses ("border" habitats). We used the rodent Calomys venustus, a species inhabiting borders in central Argentina agroecosystems, as a model to address how genetic variability is structured in linear habitats. A total of 359 rodents were captured seasonally from spring 2005 to winter 2006. Genetic variability at microsatellite loci was uniformly high, despite significant variation in population size during the sampling period. Genetic differentiation, spatial autocorrelation, and causal modeling analyses suggested that dispersion patterns in this species depend mainly on geographic distance, with unfavorable habitat like dirt roads and crop fields posing only weak (or no) resistance to dispersal. Small-scale spatial genetic structure was related to different space use patterns by females and males. Our results showed that, although greatly reduced in area, border habitats can support stable populations of species without loss of either variability or genetic connectivity. [ABSTRACT FROM AUTHOR]

Swamp rabbits (Sylvilagus aquaticus) in southern Illinois exist as a metapopulation due to fragmentation of the bottomland hardwood forests in which they live. This fragmentation makes their persistence in Illinois uncertain. We used population viability analysis (PVA) to estimate the probability of persistence of the swamp rabbit metapopulation in Illinois, using a habitat suitability map we created and life history parameters drawn from the literature. We varied the parameters used in our PVA from 50% to 150% of the initial value to compare their effects on extinction risk and to direct future management and research. We tested the effects of potential habitat loss and fragmentation by 1) removing patches individually and in groups from the analysis and by 2) adding 60, 120, and 180 m to the edge of all patches. We also tested the potential effect of dispersal corridors by increasing dispersal between connected patches. Under baseline conditions, the model suggests a 0% chance of quasiextinction (90% metapopulation decline) of swamp rabbits within 25 (or even 50) years. Changes in fecundity values and the effects of catastrophic flooding had the greatest effect on extinction risk, and changes in no other parameter yielded any appreciable impact. Removing the largest patches from the population increased the 25-year risk of extinction to 4%, whereas any other modifications to the habitat did not change the extinction risk. We suggest that managers focus on sustaining habitat quality, particularly upland habitats adjacent to occupied bottomland hardwood forests to improve the likelihood of swamp rabbit persistence in Illinois. [ABSTRACT FROM AUTHOR]

Population resilience in a metapopulation of American pikas ( Ochotona princeps) at Bodie, California, was investigated with a series of 18 detailed occupancy surveys conducted between 1989 and 2010. These were compared with earlier 1972 and 1977 censuses and earlier historical records of pikas at Bodie. There is concern that American pikas may be increasingly vulnerable to warm temperatures due to climate change, and this investigation represents the longest study of the species in a relatively low-elevation (warm) environment. The Bodie pika population represents one of the best mammalian examples of a classic metapopulation system. Annual number of observed patch extinctions (total = 114) and recolonizations (109) varied greatly among the 18 census intervals. There has been no decline in percent of patches occupied in the northern half of the study area since 1972, and the number of documented pikas in the north in recent surveys exceeded the numbers found in 1972 and 1977. In contrast, the southern half of the metapopulation collapsed during our study, apparently the result of stochasticity of metapopulation dynamics; no southern patches were occupied after 2006. The potential impact of temperature on metapopulation dynamics was examined using long-term chronic (average summer monthly maximum) and acute threshold (number of days ≥ 25°C and ≥ 28°C within a year) temperatures. There is no evidence that warming temperatures have directly and negatively affected pika persistence at Bodie. Neither warm chronic nor acute temperatures increased the frequency of extinctions of populations on patches, and relatively cooler chronic or acute temperatures did not lead to an increase in the frequency of recolonization events. Warm temperatures, however, could have impeded the dispersal of colonists moving from north to south, thus contributing to the failure of the southern region to become repopulated. [ABSTRACT FROM AUTHOR]

Habitat change due to resort development threatens rare and endemic fauna of alpine and subalpine regions. There is an urgent need to understand species persistence in such areas. The broad-toothed rat ( Mastacomys fuscus) is a rare, specialist species found in alpine and subalpine regions of Australia. We conducted fecal pellet surveys in an alpine resort to determine the species' distribution and habitat requirements. Eight individuals were radiotracked to investigate movement patterns and habitat use. Fecal pellets were found in areas of dense vegetation cover up to 1 m above ground. Home ranges were small (1,488-6,106 m2) and encompassed managed indigenous vegetation on or beside ski runs. Five individuals regularly crossed a narrow (3-5 m) cleared track. Two adult males dispersed (including traversing a wide grassy ski run) up to 1 km. The ability to cross modified areas and move throughout the landscape is proposed as a key factor facilitating the persistence of M. fuscus in the resort. Enhancing the capacity of species to move between habitat patches should be incorporated into alpine resort management plans. Such management will become increasingly important as anthropogenic disturbance increases in alpine regions. [ABSTRACT FROM AUTHOR]

Natal dispersal, the process of moving between the natal site and the site of 1st reproduction, affects a variety of ecological and evolutionary processes. Multiple factors have been suggested to influence patterns of natal dispersal in vertebrates; sex and population density are 2 of the most frequently invoked. In mammals, males are typically expected to disperse farther or more frequently than females. In contrast, theoretical predictions about the effect of population density are less clear, and support exists for both positive and negative density-dependent dispersal. Here, I investigate the influences of sex and population density on dispersal distances and spatial genetic structure (SGS) in the brush mouse ( Peromyscus boylii), using both intensive field surveys and spatial genetic autocorrelation methods. Neither density nor sex affected dispersal distances. I did detect increased genetic structure in females compared to males, a pattern consistent with male-biased dispersal. However, processes other than dispersal can generate SGS, and I suggest that in addition to sex-biased dispersal, these results also could reflect gene dispersal via mating excursions. No clear effect of population density on either dispersal distance or SGS emerged. These results highlight the importance of using multiple methodologies to investigate dispersal. Dispersión natal, el proceso de traslado entre el sitio de nacimiento y el sitio de la primera reproducción, afecta una variedad de procesos ecológicos y evolutivos. Se han sugerido múltiples factores que pueden influenciar los patrones de dispersión natal en vertebrados; el sexo y la densidad de la población son los 2 factores más frecuentemente invocados. En los mamíferos, típicamente se espera que los machos se dispersen más lejos y más frecuentemente que las hembras. En contraste, las predicciones teóricas acerca del efecto de la densidad poblacional no son tan claras, y existe apoyo para ambas formas de dispersión dependiente de la densidad, positiva y negativa. Aquí, investigo la influencia del sexo y la densidad poblacional en las distancias de dispersión y la estructura genética espacial en el ratón de maleza ( Peromyscus boylii), usando estudios de campo intensivos y métodos de auto correlación genética. Ni la densidad ni el sexo afectaron la distancia de dispersión. Detecté una elevada estructura genética de las hembras comparada con la de los machos, un patrón consistente con la expectación típica de la dispersión masculina. Sin embargo, procesos diferentes a la dispersión pueden generar estructura genética espacial, y yo sugiero que además a la dispersión sesgada por sexo, los resultados también pueden reflejar dispersión de genes a través de excursiones de apareamiento. No se apreciaron efectos de la densidad poblacional en la distancia de dispersión o en la estructura genética espacial. Estos resultados demuestran la importancia del uso de múltiples métodos para investigación la dispersión. [ABSTRACT FROM AUTHOR]

Investigating sources of infection for new disease cases is critical to effective disease management. Chronic wasting disease (CWD) was first detected among white-tailed deer ( Odocoileus virginianus) in Illinois in 2002. Although CWD was focused in northern Illinois, 4 infected deer were sampled in 2011 from locations greater than 100 km south of the disease focus. We used assignment tests ( Geneclass2 and Oncor) to determine a likely genetic source location for infected deer. Our baseline data set consisted of 310 deer sampled from 10 locations. From the baseline data set, we determined the most likely genetic source location of 15 CWD-positive and 15 CWD-negative deer. A total of 17-20% back-assigned to their sample location as their most likely genetic source location and the remainder of the animals cross-assigned to another location. The average distance between locations was 41.4 km for Geneclass2 and 43.4 km for Oncor (range 0.0-90.8 km). Distances between source and sampling locations were similar for positive and negative animals. Distances for males were greater than those for females using Oncor, but there was no difference in distance based on age. Because there are few barriers to gene flow for white-tailed deer, managers should reduce movement of deer in CWD-infected areas in an effort to reduce direct and indirect transmission of CWD. [ABSTRACT FROM AUTHOR]

Wildlife managers are challenged to manage spatially structured populations efficiently and effectively, therefore dispersal and gene flow are vital to understand and manage, particularly for a harvested species. We used a genetic approach to describe the metapopulation structure of Rocky Mountain elk ( Cervus elaphus) in Idaho to assess past patterns of population distribution and influences of harvest. We used elk tissue and DNA samples ( n = 216) to examine genetic dissimilarity between 7 regions and 9 elk management zones throughout Idaho using microsatellite loci ( n = 11). Using 5 approaches, including pairwise FST-values, assignment tests, and a Bayesian model-based clustering of genotypes, we examined the distribution of genetic variation. The distribution of genetic variation between elk populations indicated low levels of genetic differentiation among regions (expected heterozygosity [HE] = 0.55-0.61, overall FST = 0.011) and elk management zones (HE = 0.54-0.60, overall FST = 0.017). Assignment tests and migration rates indicated directional gene flow between elk populations. A patchy metapopulation best describes the distribution of genetic variation among Idaho elk populations because likely enough individual interchange occurs between geographically separated populations. The elk populations we sampled could be part of a geographically larger patchy metapopulation potentially stretching from Yellowstone National Park through Idaho into western Canada. Because of historical translocations of elk from Yellowstone National Park, insufficient time may have passed to detect differences in genetic variation. Subtle differences in the distribution of genetic variation were observed in 2 of the 9 elk management zones within 2 different regions of the state. Our findings indicate management of Idaho elk populations and dispersal are maintaining sufficient gene flow. Metapopulation structure of a harvested species based on the distribution of genetic variation is an indicator of potential genetic consequences of harvesting and sustainable harvest levels. [ABSTRACT FROM AUTHOR]

Many demographic parameters of imperiled fishers (Martes pennanti) in the Pacific Northwest remain poorly understood but are necessary to develop conservation strategies; herein we report on fisher reproduction, recruitment, and dispersal on the Hoopa Valley Indian Reservation, California, to help fill key knowledge gaps. Forty radiocollared, breeding-age females exhibited denning behavior on 80 (87%) of 92 opportunities between 2005 and 2011. Twenty-eight female fishers weaned offspring in 55 (65%) of 85 adequately monitored denning opportunities. Two-year-old female fishers were less likely than older females to den and wean kits. We counted 52, and extracted and marked 51, kits comprising 28 litters of 19 females between 2005 and 2008. Average litter size was 1.9 kits (27 females, 24 males, and 1 unknown) 4-12 weeks postbirth. Mean distances between natal dens and centroids of newly established ranges for 7 juvenile females was 4.0 km (range = 0.8-18.0 kin); this distance for 1 male was 1.3 km. The recruitment rate of juveniles that successfully established a home range per adult female was 0.19 (0.16 for females and 0.02 for males). Our results suggest that managers should work toward increasing female survival rates and consider translocations to increase and expand existing fisher populations. [ABSTRACT FROM AUTHOR]

Following dispersal from 1 group, individuals may join other established social groups. Such intergroup transfer may increase access to potential mates and decrease mate competition. We used data from 402 individuals to examine patterns of intergroup transfer in prairie voles (Microtus ochrogaster). Nearly 32% of established social groups (single female units, male-female pairs, or communal groups of at least 2 adults of the same sex) were joined by 1 or more individuals. Most individuals (76%) that joined social groups were wanderers that were either unmarked, recently marked during grid trapping, or marked transients; 70% were males. Joining a group was not contingent upon recent disappearance of residents. Total number of residents positively affected the probability of a female joining a social group, whereas number of adult female residents and population density negatively affected it. Some individuals (24%) moved directly from one group to another without an intervening wandering stage; we refer to these instances of intergroup transfer as direct transfers. Most direct transferers moved into nearby groups, but not the closest group. Males were more likely than females to directly transfer into groups with potential mates and without potential competitors. Thus, males directly transferred in a manner consistent with maximizing reproductive opportunities. In contrast, 25% of females directly transferred into groups without potential mates and 96% into groups with at least 1 adult female. Females may be less constrained by group composition with respect to potential mates because wandering males, with which females can mate, are prevalent. All-male groups almost never occur in our population, so females probably cannot avoid joining groups with competitors. [ABSTRACT FROM AUTHOR]

North American caribou (Rangifer tarandus) herds commonly exhibit little nuclear genetic differentiation among adjacent herds, although available evidence supports strong demographic separation, even for herds with seasonal range overlap. During 1997-2003, we studied the Mentasta and Nelchina caribou herds in south-central Alaska using radiotelemetry to determine individual movements and range overlap during the breeding season, and nuclear and mitochondrial DNA (mtDNA) markers to assess levels of genetic differentiation. Although the herds were considered discrete because females calved in separate regions, individual movements and breeding- range overlap in some years provided opportunity for male-mediated gene flow, even without demographic interchange. Telemetry results revealed strong female philopatry, and little evidence of female emigration despite overlapping seasonal distributions. Analyses of 13 microsatellites indicated the Mentasta and Nelchina herds were not significantly differentiated using both traditional population-based analyses and individual-based Bayesian clustering analyses. However, we observed mtDNA differentiation between the 2 herds (FST = 0.041, P < 0.001). Although the Mentasta and Nelchina herds exhibit distinct population dynamics and physical characteristics, they demonstrate evidence of gene flow and thus function as a genetic metapopulation. [ABSTRACT FROM AUTHOR]

Numerous model systems have informed classical ideas of the deterministic structure of natural communities. Although a number of important insights have been gained from desert rodents, little is known regarding the relative role of local environmental and spatial processes that embody the emerging metacommunity paradigm in structuring these model systems. We compared patterns of community composition based on environmental characteristics and estimates of spatial isolation by distance to test predictions characterizing contemporary models of metacommunity structure. Analyses were based on rodent community structure at 31 sites within the Mojave Desert. Consistent with previous studies of rodent communities, local environmental characteristics accounted for a significant amount of variation in community structure. Nonetheless, spatial isolation by distance contributed significantly to structure as well, even after accounting for the shared effect between environmental and spatial descriptors. Indeed, regional collections of rodent communities represent metacommunities and a metacommunity perspective promises to complement much that has been learned from primarily local perspectives. Examination of data suggested that the mass effects model of metacommunity structure may best describe regional patterns of species composition, at least for this data set. Moreover, 2 further important insights emerge from analyses. First, important life-history differences among taxa translate into different spatial effects that are likely due to dispersal abilities. Second, despite the spatially uncorrelated nature of environmental variation across our sampling array much of the structure of this metacommunity could be attributed to the shared effects of spatial and environmental characteristics. Typically, empirical analyses of metacommunity structure have attributed this variation to spatial structure generated by environmental spatial autocorrelation, but our analyses suggested that this component of variation may to some degree represent a unique yet underappreciated spatial effect. Moreover, this substantive component of variation suggests that prior analyses of empirical metacommunity structure provide conservative estimates of regional spatial effects and that the role of dispersal in determining metacommunity structure may be greater than is commonly considered. [ABSTRACT FROM AUTHOR]

Commercial harvest severely reduced the abundance of New Zealand fur seals (NZFSs; Arctocephalus australis forsteri), and the subspecies may have become regionally extinct in Western Australia (WA). NZFS populations are now expanding in WA and this study aimed to determine the origin of these populations and distinguish local recruitment from external recolonization. Mitochondrial cytochrome-b gene sequences were obtained from 137 NZFSs from breeding colonies in WA and South Australia (SA), and analyzed with sequences from Tasmania and New Zealand. Genetic differentiation among WA and SA populations was low, indicating extensive genetic exchange throughout this large region. Three unique haplotypes, however, were recorded from WA, supporting the local recruitment hypothesis. Moreover, a test for asymmetrical gene flow identified a predominance of migration from WA to SA, suggesting a role of WA NZFSs in the recovery of more heavily exploited SA NZFS populations. Significant genetic differentiation was evident between SA and Tasmania, indicating limited genetic exchange despite the close proximity of these populations. Examination of our data suggests NZFSs were not extirpated from WA, have retained unique genetic variants, and that peripheral, low-density populations may have had a role in the recolonization of heavily exploited populations. [ABSTRACT FROM AUTHOR]

Molecular genetics tools have been used recently to investigate aspects of bat biology, including the degree of male- and female-driven gene flow among populations. However, none of this work has focused on the little brown bat (Myotis lucifugus), one of the most common bats in North America. Previous work using mark--recapture suggests that like many mammals, including other temperate vespertilionid bats, gene flow in this species is largely driven by males, whereas females return to the roosts in which they were born to rear pups. To determine if this species displays a pattern of population genetic structure that is consistent with this hypothesis I sampled 182 female M. lucifugus at 12 maternity colonies throughout Minnesota. Using a portion of the mitochondrial gene cytochrome b and 10 polymorphic nuclear microsatellites, I found significant structure among colonies, and population differentiation was slightly higher for the mitochondrial locus. This supports the hypothesis that female M. lucifugus display some degree of natal philopatry, but the inferred female dispersal rate was high. The pattern of structure was complex and demonstrates that unequal gene flow among maternity colonies is occurring and that the co-occurrence of breeding populations within maternity colonies and/or inbreeding could be confounding estimates of population genetic structure among these colonies. The patterns of population genetic structure and natal philopatry imply that both seasonal migration and dispersal by females should be considered as possible factors in the spread of emerging infectious diseases such as white-nose syndrome. [ABSTRACT FROM AUTHOR]

Movement patterns and habitat selection are influenced by factors such as resource availability, predation risk, and social interactions, and the relative importance of each of these variables can change over an animal's life span. Although ranging patterns and habitat use of adult dolphins have been explored in some areas, relatively little is known about how these behaviors develop as young dolphins mature. This study explored natal philopatry during the juvenile period and behavioral development of ranging and habitat-use patterns in newly independent bottlenose dolphins (Tursiops truncatus) at a long-term study site in Sarasota Bay, Florida. To achieve this we used both long-term sighting data from the resident dolphin community in Sarasota Bay and new information on movements, habitat selection, and social associations collected through boat-based focal- animal behavioral observations on 27 individually identifiable juveniles during 2005--2008. We documented differences in ranging patterns and habitat use of juvenile dolphins by sex, season, and age, and investigated the degree of maternal influence on these behaviors and the functional significance of juvenile groups. We found that male and female dolphins in Sarasota Bay had similar ranging and habitat-selection patterns during the juvenile period. Both sexes exhibited a high degree of philopatry to natal areas as juveniles, with dispersal occurring only rarely by members of either sex. Seasonal and age-related differences in juvenile behavior were evident, and lasting maternal influences on habitat selection and ranging patterns postindependence are apparent. These findings provide some of the 1st information on juvenile marine mammal behavior that contributes to our understanding of resident inshore dolphin behavior throughout the life history and are potentially important to management and conservation efforts. [ABSTRACT FROM AUTHOR]

Black-footed ferrets (Mustela nigripes) apparently were extirpated from all native habitats by 1987, and their repatriation requires a combination of captive breeding, reintroductions, and translocations among sites. Improvements in survival rates of released ferrets have resulted from experience in quasi-natural environments during their rearing. Reestablishment of a self-sustaining wild population by 1999 provided the 1st opportunity to initiate new populations by translocating wild-born individuals. Using radiotelemetry, we compared behaviors and survival of 18 translocated wild-born ferrets and 18 pen-experienced captive-born ferrets after their release into a prairie dog colony not occupied previously by ferrets. Translocated wild-born ferrets moved significantly less and had significantly higher short-term survival rates than their captive-born counterparts. Using mark--recapture methods, we also assessed potential impacts to the established donor population of removing 37% of its estimated annual production of kits. Annual survival rates for 30 ferret kits remaining at the donor subcomplex were higher than rates for 54 ferret kits at the control subcomplex (unmanipulated) for males (+82%) and females (+32%). Minimum survival of translocated kits did not differ significantly from survival of those at the control subcomplex. Direct translocation of young, wild-born ferrets from site to site appears to be an efficient method to establish new populations. [ABSTRACT FROM AUTHOR]

Radiotelemetry was used during 1983 and 1984 to collect information on short-term areas of activity for black- footed ferrets (Mustela nigripes) near Eyeteeth, Wyoming. This population ultimately provided ferrets for the captive-breeding program that bred and released offspring into the wild since 1991. We fitted 5 adult ferrets and 13 juveniles with radiotransmitters and followed their movements during late summer and fall. Adult males had 7-day areas of activity that were >6 times as large as those of adult females. Activity areas of adult males varied little in coverage or location on a weekly basis, but females sequentially shifted their areas. Unlike juvenile females, juvenile males tended to leave their natal colonies. [ABSTRACT FROM AUTHOR]

In many mammals social organization promotes genetic structuring, which can be influenced by the dispersal pattern of the species. We analyzed the population genetic structure and dispersal of white-lipped peccaries (Tayassu pecari) from the Pantanal, Brazil. We genotyped 100 individuals at 7 microsatellite loci from 2 adjacent locations with no obvious geographic barrier between them. We found a significant but low FST value, and the Bayesian analysis indicated a unique cluster. No significant differences were observed between mean assignment indices of resident males and females from both locations, and the probability of being born at the location sampled of >30% of the individuals analyzed was lower than average. Mean relatedness between resident female, male, and opposite-sex pairs was not statistically different in both locations. These results suggest a low degree of genetic differentiation between the locations analyzed, and dispersal by both sexes (contrary to the predicted male-biased dispersal of most mammalian species). [ABSTRACT FROM AUTHOR]

Capybaras, (Hydrochoerus hydrochaeris) are large, herbivorous New World hystricomorphs, common in the seasonally flooded savannas of tropical and subtropical South America. In this paper we review the social structure and dynamics of capybaras across much of their geographic range. Wherever they have been studied capybaras live in groups. Capybara groups are stable social units composed of adult males and females (sex ratio biased toward females) with their young. A linear dominance hierarchy characterizes interactions among males, and the dominant male obtains most matings. Group sizes range from 6 to 16 adult members and vary with habitat characteristics and population density. At higher densities group sizes and the proportion of floaters (apparently unaffiliated animals; mostly males) increase. In 1 low-density location dispersal appears to occur in groups of both sexes, whereas in another location, where density is higher, males disperse and females are philopatric. We also discuss more conceptual issues (mostly proximate and ultimate mechanisms) that relate to intraspecific variation in social behavior in general, and capybaras in particular. [ABSTRACT FROM AUTHOR]

Fragmentation of wildlife populations can have detrimental effects, including genetic differentiation of populations, loss of genetic diversity, and inbreeding depression. We evaluated the genetic structure among isolated colonies of black-tailed prairie dogs (Cynomys ludovicianus) along an urban gradient in southern Denver, Colorado. Urban colonies are important ecologically and for educational purposes, and they serve as source populations for relocation efforts. Levels of genetic differentiation between colonies were high relative to colonies in natural habitat at comparable or greater distances. Prairie dog colonies depend on dispersal among colonies for long-term persistence, and we found evidence for reduced but measurable rates of movement of individual prairie dogs among urban fragments. We observed a trend for smaller and more isolated colonies to exhibit lower genetic diversity, but we did not detect inbreeding in any of the colonies sampled. Isolation-by-distance measures, including measures based on permeability of various features of urban habitat such as roads and development, did not explain genetic differences. Our system represents a possible end point in the genetic consequences of continued loss and isolation of prairie dog colonies as fragmentation increases in both urban and natural landscapes. Urban development could affect dispersal in unexpected and complex ways and requires further study, but prairie dog colonies and their associated wildlife communities in urban areas have the potential for long-term persistence if not extirpated by human activity. [ABSTRACT FROM AUTHOR]

Dispersal and gene flow are significant components of metapopulation structure and dynamics. We examined gene flow in the pygmy rabbit (Brachylagus idahoensis), a sagebrush specialist that occurs in small, isolated populations in the Great Basin region and is believed to have limited dispersal abilities. We examined genetic diversity, gene flow, and population genetic structure, and investigated the effects of putative barriers to gene flow in 8 sample locations within 2 study areas in Idaho during 2002-2006. Potential barriers included secondary roads, highways, creeks, and agricultural pastures. Distance between sample locations ranged from 0.5 to 32 km. We expected that gene flow would be limited and that moderate levels of genetic structure would be apparent among sample locations separated by barriers and distances over several kilometers. However, analyses based on 15 microsatellite loci from 239 rabbits revealed low to moderate levels of genetic differentiation among sample locations. Bayesian cluster analyses suggested that sample locations separated by <14 km comprised 1 genetic cluster with high levels of gene flow among sample locations within clusters. We documented no significant evidence of a sex bias in dispersal based on sex-specific FST among sample locations, and relatedness (r), mean assignment index (mAI), and variance of assignment index (vAI) within sample locations; however, spatial autocorrelation suggested that juvenile females might disperse farther than males. These results indicate that dispersal capabilities of pygmy rabbits greatly exceed previous estimates, and that creeks and roads were not effective barriers to gene flow in our study areas. [ABSTRACT FROM AUTHOR]

The genetic structure of brown hyena (Hyaena brunnea) populations in any part of their distribution is unknown. Brown hyenas live in clans whose territories and membership change, making nongenetic estimates of population structure and relatedness among individuals difficult to establish. Sixty-one brown hyenas from the west coast of Namibia were genotyped at 10 microsatellite loci designed for the spotted hyena (Crocuta crocuta). We found reduced microsatellite variation in brown hyenas compared to spotted hyenas. Using nonhierarchical analyses we detected no major genetic subdivisions across the area sampled in Namibia, but weak differentiation among 2 clans in the southern portion of the range. Females within clans were significantly more related (rwc⚢ 5 0.34 ± 0.072 SE) than females between clans (rbc⚢ 5 0.022 ± 0.033) and than females and males in clans (rwc⚢= 5 0.058 ± 0.076). Examination of these data indicates that dominant males were not related to dominant females and that there is multiple paternity within clans. [ABSTRACT FROM AUTHOR]

Sea otter (Enhydra lutris kenyoni) movements, home range, and activity budgets were described from data collected during very-high-frequency radiotelemetry studies of 75 individuals on the outer coast of Washington State between 1992 and 1999. Sea otters were located at least once per week from 22 accessible sites along the coast. Over the 7-year study period, range expansion occurred from the core range north and east into the Strait of Juan de Fuca (SJF) as well as southward on the outer coast. Forty-three percent of the sea otters moved into the SJF at least once, most often in winter, using habitat that had not been occupied by sea otters since their extirpation 100 years ago. All sea otters spent portions of their time in the vicinity of Cape Alava, and many animals demonstrated consistent periodic seasonal shifts between specific portions of the coastline over several years. Ninety-five percent annual linear home ranges differed between sex and age classes. Adult males used the largest amount of coastline (50 km ± 9 SD) and subadult females used the least (24 ± 9 km). Both adult males and females demonstrated high seasonal periodicity in range use in summer and winter. Twenty-four--hour time budgets in the core portion of the range revealed on average sea otters spent 41% ± 14% SD of the time foraging and 45% ± 13% of the time resting (age and sex classes pooled). Adult and subadult female sea otters were most frequently found resting and foraging close to shore (<1,000 m) and in shallow water (0-10 m), whereas adult and subadult males rested and foraged >1,000 m offshore and at depths between 10 and 30 m. Given current rates of population growth and observed mobility, sea otters in Washington have high potential for range expansion into unoccupied habitat such as Grays Harbor, Willapa Bay, the SJF, or along Vancouver Island. [ABSTRACT FROM AUTHOR]

The central Rocky Mountain region of North America lies at the biogeographic crossroads of the Rocky Mountains, Great Plains, and Great Basin. Here, we examine genetic patterns in an abundant, widely distributed, and ecologically important rodent species, the long-tailed vole (Microtus longicaudus), across this climatically and tectonically dynamic landscape. We examine patterns of genetic diversity in relation to the species' overall phylogeographic distribution using mitochondrial cytochrome-b sequences from modern, historic, ancient, and published samples. Our analyses reveal extensive genetic diversity in the central Rockies, a lack of population structure, and a lack of concordance between genetic and morphological subspecies distributions. Patterns of genetic variation in late-Holocene and modern populations are similar. We conclude that geographical features such as the Continental Divide, previously isolated glacial cover, and major rivers do not result in persistent genetic structure within the long-tailed vole. We also conclude that the central Rocky Mountain region is a zone of secondary contact for divergent mitochondrial lineages of the long-tailed vole. [ABSTRACT FROM AUTHOR]

Olympic marmots (Marmota olympus) are large, burrowing rodents inhabiting scattered subalpine meadows on the Olympic Peninsula, Washington. Recently, the population has declined and become increasingly fragmented. The ability of Olympic marmots to recolonize abandoned habitat and to maintain gene flow among extant populations will depend on the number and success of dispersers and the distances that they travel. We monitored 84 radiotagged Olympic marmots to determine dispersal rates, distances, and success. Contrary to previous observations, 3-year-olds were most likely to disperse, although some 2-year-olds and even some older animals, particularly males, moved as well. Of marmots known to be still on their natal home range in the spring of a given year, 16% of 2-year-old males, 50% of 3-year-old males, 17% of 2-year-old females, and 29% of 3-year-old females subsequently dispersed. Dispersal rates for 3-year-olds were slightly lower when all animals were included in the analysis regardless of whether their dispersal history was known. Males dispersed farther than females (median = 984 m, n = 14 versus median = 267 m, n = 13) and 69% of females settled within 500 m of their original home range. If the observed dispersal patterns are representative of range-wide patterns and if Olympic marmot densities remain low, successful dispersal may be too infrequent to sustain reliable recolonization of vacant habitats or even genetic or demographic rescue of isolated marmot groups. [ABSTRACT FROM AUTHOR]

Space use in mammals may vary between the sexes. This may reflect demographic or reproductive differences between the sexes as well as different responses to changes in resource availability. We present the results of a 2-year study on the spatial organization of the yellow-necked mouse (Apodemus flavicollis) in a beech woodland in the eastern Italian Alps. We used radiotelemetry to monitor the movements of 64 mice during the breeding season (i.e., from July to October) in 2005 (high population density) and 2006 (low population density). In both years, home ranges of males were significantly larger than those of females and overlapped with the areas occupied by several individuals of both sexes. Females monopolized core areas and never shared burrows with other females--suggesting intrasexual territoriality--although their home ranges overlapped those of several males. Space use changed seasonally and among years, suggesting a relationship with resource abundance and distribution. Females exhibited reduced spatial exclusivity and larger home ranges during lower food availability; males varied their spatial distribution accordingly by also expanding their home ranges. After a decrease in habitat quality, we observed substantial and abrupt adult dispersal by both sexes. In sum, females varied their spatial and social relationships in response to environmental conditions, whereas males appeared to vary patterns of space use in response to females. [ABSTRACT FROM AUTHOR]

Multiple factors likely influence natal dispersal behavior of juvenile mammals, which is typically male-biased. Because of their small body size and specific habitat requirements, pygmy rabbits (Brachylagus idahoensis) are expected to exhibit limited dispersal. We predicted that dispersal would be male-biased, that juveniles born later in the year would disperse farther, and that juveniles would be more likely to disperse away from areas of higher habitat saturation. We used radiotelemetry to study dispersal of 61 juvenile pygmy rabbits (31 males and 30 females) from shortly after emergence from natal burrows (April-July) to the beginning of the next breeding season (mid-March) during 2004-2006. Juveniles dispersed before 12 weeks of age, and typically completed dispersal movements within 1 week. Both sexes exhibited a high rate of dispersal (males = 90%; females = 80%); however, juvenile females settled more than 3 times farther from their natal areas than males. Median natal dispersal distances for males and females were 1.0 km (range = 0.03-6.5 km) and 2.9 km (range = 0.02-11.9 km), respectively. Dispersing juveniles crossed gravel roads and perennial streams; however, rabbits tended to initiate dispersal movements away from nearby streams. Mortality rates for male and female juvenile rabbits were 69.2% and 88.5%, respectively, and were highest during the first 2 months after emergence from the natal burrow. We found no evidence that date of emergence, body condition, or habitat saturation influenced dispersal frequency or distance in juvenile pygmy rabbits. Results indicate that pygmy rabbits are capable of dispersing long distances and suggest that their conservation will require land management at broader spatial extents. [ABSTRACT FROM AUTHOR]

Mating behavior and social structure can influence genetic structure within and between populations, yet most studies focus on highly kin-structured, polygynous species. The North American beaver (Castor canadensis) is socially monogamous; however, examination of recent genetic data suggests that this species may be opportunistically promiscuous. We used 7 microsatellite loci to quantify genetic structure within and between 2 beaver populations in Illinois. An analysis of molecular variance revealed significant genetic subdivision among breeding groups in southern Illinois (FST = 0.086, P < 0.001), whereas regional genetic subdivision was evident in central Illinois (FST = 0.037, P < 0.001). Overall FST between populations also was significant (0.068 ± 0.012 SE, P , 0.001). Bayesian clustering assigned individuals from the 2 geographic sampling regions into 2 distinct genetic clusters with 70% of individuals assigned to 1 of the 2 clusters. Migration between populations was low at 0.16 individuals/generation (confidence interval = 0.0079-0.33). Estimates of population subdivision, cluster analysis, and dispersal indicate that these populations are genetically distinct, but are connected by infrequent dispersal. [ABSTRACT FROM AUTHOR]

Knowledge of seasonal movements by pronghorns (Antilocapra americana) within the easternmost extension of sagebrush-steppe communities is limited. Current hypotheses regarding movement patterns suggest that pronghorns initiate seasonal movements in response to severe winter weather, snowfall patterns, spatial and temporal variation in forage abundance, and availability of water. From January 2002 to August 2005, we monitored movements of 76 adult (≥1.5 years) female pronghorns on 2 study areas (Harding and Fall River counties) in western South Dakota. We collected 8,750 visual locations, calculated 204 home ranges, and documented 17 seasonal movements. Eighty-four percent (n = 55) of pronghorns were nonmigratory and 10% (n = 6) were conditional migrators. Mean distance between summer and winter range was 23.1 km (SE = 2.8 km, n = 13). Five adult pronghorns (8%) dispersed a mean distance of 37.6 km (SE = 12.4 km); of which 1 female moved a straight-line distance of 75.0 km. Winter and summer home-range size varied (P < 0.0001) between study sites. Mean 95% adaptive kernel winter and summer home-range size of pronghorns was 55.5 and 19.7 km², respectively, in Harding County and 127.2 and 65.9 km², respectively, in Fall River County. Nonmigratory behavior exhibited by pronghorns was likely associated with minimal snow cover and moderate temperatures during winter 2002-2004. Variation in size of adult seasonal home ranges between sites was likely associated with differences in forage distribution and availability between regions. [ABSTRACT FROM AUTHOR]

Although the brown bear (Ursus arctos) is generally classified as an endangered species, the size and range of several bear populations are increasing in different parts of the world. Understanding how this occurs is essential for the species' management. Using reliable signs of bear presence and models, we analyzed multiple aspects of the spatial expansion of the brown bear population in Slovenia from the Core Bear Protective Area (an area established in 1966 for the conservation of brown bears; hereafter, Core Area) toward the Alps and other parts of the country in 1945-1995. Bear population densities increased between 1945 and 1995, but densities decreased with distance from the Core Area. The observed proportion of females increased overall during the study period from 6% to 20%, but decreased with distance from the Core Area from 27% (0-10 km from the Core Area) to 5% (>70 km from the Core Area). This pattern likely is a consequence of male-biased dispersal, which can cause substantial changes in the sex structure of peripheral parts of populations in space and time. The population showed a net annual growth rate of 1.7%, and expanded spatially at an average rate of 1.6-1.9 km/year. Some females were recorded far from the Core Area (>80 km), suggesting that unlike in stable or declining populations, females in expanding populations can exhibit long-distance dispersal. However, the frequency of females that dispersed far was so small that it probably had little impact on the dynamics of the population expansion. [ABSTRACT FROM AUTHOR]

The prevailing view of the social organization of temperate bats is that maternity colonies represent aggregations of philopatric females connected to other maternity colonies via male-mediated gene flow. However, few studies have examined fine-scale patterns of matrilineal diversity within and between colonies, and clear evidence of strict philopatry generally is lacking. Here we examine patterns of genetic diversity within and among maternity colonies of big brown bats (Eptesicus fuscus) using both microsatellites and mitochondrial sequences. As in other temperate bats, we observed no differentiation among colonies using nuclear microsatellite markers (FST: -0.0001-0.012; 99.5% of variation within populations). Overall, there was significant mitochondrial structure among colonies, but the pattern was complex, with low θST values among some populations and high values among others (range: -0.007-0.491). Three groups of colonies were identified in nested analyses of molecular variance, among which variation was high (21.2% of the variation), but within which variation was low (1.4%), and significant matrilineal isolation by distance (r = 0.56, P = 0.012) was observed. Maternity colonies were characterized by high haplotype diversity (h ¯ = 0.83) and a large number of matrilines (5-15) per colony. Furthermore, we observed a small number of maternities within colonies, and only 5-17% (_ = 9%) of the sampled females were found roosting with a mother or daughter. Our results are inconsistent with strict female philopatry, and suggest that female-mediated gene flow may occur among some maternity colonies. The potential for female dispersal in temperate bats prompts new and exciting questions about social and dispersal dynamics. [ABSTRACT FROM AUTHOR]

We investigated movement patterns in a high-density population of Eurasian badgers (Meles meles) to explore how the costs and benefits of dispersal and other forms of movement differed among individuals in the population. We analyzed a 17-year data set comprising 5,255 trapping events for members of a population of Eurasian badgers at Wytham Woods, Oxford, United Kingdom. For a subset of badgers with a sufficient trapping history, we were able to identify dispersal events. Permanent dispersal was not common. Of 267 badgers 1st trapped as young and caught on a minimum of 4 occasions spanning 400 days or more, the majority (75.8%) were never captured at more than 2 social groups. Only 51 (19.1%) of these animals satisfied our definition of dispersal; 96 (35.8%) were never captured outside of their natal social group. Male badgers moved between groups more than did females and accumulated more wounds in the process. Dispersing males tended to move to larger groups and to groups with a preponderance of females, but dispersal rate did not change as the density of the population increased. However, evidence of extraterritorial matings suggests that inbreeding may be alleviated without dispersal. We consider the implications of these findings for the mating system and social behavior of the badger. [ABSTRACT FROM AUTHOR]

Spatial synchrony is a common feature of mammalian population dynamics that appears to be caused by different processes in different systems. We sampled 60 sites across >900 km in northern and central Ontario, Canada, from 2001 to 2004 to assess spatial and temporal trends in abundance and population growth of small mammals. We tested alternative predictions for 3 causes of synchrony: dispersal, predation, and correlated environmental perturbations (the Moran effect). During 25,680 trap nights, Myodes gapperi, Tamias striatus, and Peromyscus maniculatus were the most commonly captured species. Populations of all 3 species fluctuated markedly during the 4 years of sampling, but fluctuations appeared to occur over a relatively small spatial extent (<200 km for all species). No pairwise combination of species exhibited positive interspecific synchrony, suggesting that nomadic predation was not synchronizing declines among species. Our data were most consistent with the dispersal hypothesis or a Moran effect caused through synchronous food crops. [ABSTRACT FROM AUTHOR]

The tuco-tuco das dunas (Ctenomys flamarioni) is a subterranean rodent endemic to sand-dune ecosystems along the southern coast of Brazil. We studied 3 populations that differed in the degree of human impact, and used direct and indirect methods to assess demographic and genetic information. Field studies revealed a tendency toward a female-biased sex ratio, and sexual dimorphism in both weight and length in all 3 populations. This evidence supports a hypothesis of polygyny in C. flamarioni. Using 9 microsatellite loci, we explored patterns of variation and genetic structure among the populations. Our findings suggested that the Xangri-hi and Remanso populations, living in more-disturbed locations, could have experienced demographic reductions in population size, but not the Pinhal population. However, other factors such as a polygynous breeding system and the environmental instability that characterizes the coastal dunes may have influenced the observed pattern. Analysis of genetic structure revealed strong differentiation among populations, but no significant structure at the intrapopulation level, Nonsignificant values for the tested indices from assignment tests (FST, FIS, MAIc, and vAlc) over population showed no evidence of sex-biased dispersal. The same was observed from analyses of molecular variance. Nevertheless, lower pairwise FST and higher Nm values between males from Xangri-á and Remanso indicated greater gene flow among males, suggesting a slightly male-biased dispersal pattern. Significant differences in interpopulation dispersal patterns were clearer among females, with greater dispersal for females from Pinhal than those at Remanso and Xangri-lá. [ABSTRACT FROM AUTHOR]