In the midwestern United States, grassland habitat is fragmented by row-crop agriculture and urbanization. In spring and early summer, grassland animals facing a decision to either enter a fallow crop field or detour around it likely balance trade-offs between predation risk and travel costs, similar to forest animals encountering a clear-cut. We tested if Franklin's ground squirrel (Poliocitellus franklinii), a grassland mammal, based gap-crossing decisions on lengths of alternate movement routes or on energetic constraints by translocating radiocollared adult squirrels across crop fields and tracking their routes home. Giving-up densities of food resources from a field experiment indicated that Franklin's ground squirrels perceived a higher risk of predation in crop fields than in grass, but squirrels did not appear to compensate for risk by adjusting travel speed through crop fields. Body mass was the only predictor of gap crossing; lighter squirrels were more likely than heavier squirrels to cross crop fields. Squirrels did not appear to base gap-crossing decisions on detour efficiency (distance across gap divided by distance of detour). Additionally, likelihood of homing within 24 h of release decreased with increasing crossing distance. The importance of body mass in gap-crossing decisions by Franklin's ground squirrels suggests that movements through heterogeneous landscapes are partly explained by trade-offs between predation risk and energetic constraints.

We reviewed the literature on burrows of North American ground-dwelling squirrels to assess factors influencing burrow length and depth. Prior research suggested that soil characteristics and burrow age can influence burrow dimensions; we extended these findings by evaluating the influence of body size, temperature stress, and degree of sociality. We found that body size was positively correlated with burrow length and depth, probably because larger species require more space for underground activities. This relationship did not hold for Marmota monax and M. flaviventris, for unknown reasons. Burrow length scaled allometrically with body mass (b = 0.72), possibly because the metabolic effects of limited ventilation in burrows placed a constraint on burrow length. Temperature stress was not related to burrow depth, perhaps because of the insulation provided by snow and soil. The more highly social species excavated longer burrow systems, probably because of the greater space needs of multiple residents per burrow.

We examined intraspecific relationships in the eastern fox squirrel (Sciurus niger) and the eastern gray squirrel (S. carolinensis) using sequence variation in a portion of the mitochondrial DNA cytochrome-b gene and part of the D-loop in the control region. These closely related species are codistributed temperate forest obligates that have similar generation time and population ecologies. For both species, we documented high haplotype diversity, low nucleotide variation, and several groups of divergent haplotypes. However, there is a general lack of spatial structure in maternal lineages within each species. For S. carolinensis, we observed a pattern of population genetic structure that suggests the presence of at least 2 distinct refugial populations that evolved in isolation during the Pleistocene (approximately 98.3–266.3 thousand years ago [kya]) and subsequently expanded to the species' current range following the last glacial maximum. For S. niger, the genetic structure was much less pronounced, with fewer strongly diverged haplotypes. This finding suggests that eastern fox squirrels persisted in either a single population in a glacial refugium or as several refugial populations that maintained gene flow throughout the Pleistocene. For both species, there is evidence that scattered populations were present in multiple, small refugia close to the Laurentide Ice Sheet, allowing rapid range expansion following glacial recession. Taken together, our results indicate that S. niger and S. carolinensis underwent multiple episodes of genetic divergence during isolation in glacial refugia, followed by range expansion and contact that resulted in admixture of divergent maternal lineages within each species during interglacials. Examination of our data further indicates that the most recent range expansion in both species occurred within the past 12–20 kya.

Herbivores can sometimes benefit the plants they consume. We investigated the interaction between an herbivore species, the Taiwan field vole (Microtus kikuchii), and its major food plant, the Yushan cane (Yushania niitakayamensis) of alpine meadows. We observed consumption of Yushan canes by voles in the field and laboratory, performed 2 field manipulative experiments and 2 laboratory cafeteria feeding experiments, and carried out chemical analyses on different Yushan cane parts to test 2 hypotheses: Taiwan field voles feed preferentially on certain Yushan cane parts due to their different chemical constituents, which vary with season; and herbivory by the Taiwan field vole has positive effects on fitness of Yushan cane. Our results showed that, although Taiwan field voles could exert a strong herbivorous pressure on Yushan canes through their near year-round preference for feeding on Yushan cane leaves, the presence of Taiwan field voles actually increases the emergence of Yushan cane shoots over time. The feeding preference of voles for different plant parts can be explained by plant chemical constituents. We demonstrated that the consumption behavior of voles, which reduces the canopy and creates large litter piles, could facilitate the production of Yushan cane shoots by creating favorable shooting conditions. This study suggests a behavioral mechanism of overcompensation where the gain in asexual reproduction by Yushan cane more than compensates the loss to herbivory by the Taiwan field vole.

The Preble's meadow jumping mouse (Zapus hudsonius preblei [PMJM]) is a rare rodent of southeastern Wyoming and central Colorado that has been the center of debates regarding subspecies' genetic identity and the application of the Endangered Species Act. I analyzed a 7-year PMJM mark–recapture data set using a temporal symmetry model (Pradel model) to estimate apparent survival (ϕ), recruitment (ƒ), population change (λ), and vital rate influence on λ. Deer mouse (Peromyscus maniculatus) captures depressed ϕ, suggesting that competition for resources may decrease PMJM survival. Vole-mediated habitat changes or voles' affinity for quality riparian habitats may explain why PMJM ϕ and ƒ increased with meadow vole (Microtus pennsylvanicus) captures. Based on early-summer and late-summer sampling from 2000 to 2006, λ estimates were 0.87 ± 0.06 SE and 0.87 ± 0.11 SE, respectively, and ƒ had a greater influence on λ than did ϕ. This PMJM population is losing connectivity to eastern, northern, and southern tributaries from habitat degradation and storm-water and municipal runoff erosion. The loss of the adjoining habitat and the PMJMs that were supported by this habitat prevents new recruitment via immigration. Because of the importance of recruitment to PMJM population stability, tributaries and the riparian habitat along these tributaries are vital to PMJM conservation. Scale-appropriate habitat sampling, assessments of reproductive success, and detailed demographic studies to estimate vital demographic parameters will help identify how particular habitat components impact fecundity and immigration.

We tested the hypothesis that domestic sheep (Ovis aries) in alpine meadows of central Norway negatively affect populations of field voles (Microtus agrestis) because grazing reduces cover and increases the concentration of secondary compounds in forage plants. We maintained 3 treatments for 3–4 years on 11 experimental plots. Treatments included fencing to remove sheep; fertilization to improve forage quality; and grazed, unfertilized controls. Within experimental plots we collected data on cover of vascular plants, forage quality (nitrogen, fiber, and secondary compounds), and indicators of performance for vole populations (summer density, winter activity, and body size). Sheep appeared to reduce the cover of vascular plants, but quality of 4 species of forage plants showed little response to grazing. Concentrations of nitrogen in forage increased on fertilized plots, as did the ratio of nitrogen/(fiber plus phenolic compounds). Voles occurred sporadically on the experimental plots, however, and indicators of vole performance differed little among treatments. Furthermore, the quality of preferred food (Carex bigelowii) of voles showed no clear response to fertilization, and the activity of voles on plots showed no significant correlation with quality of C. bigelowii irrespective of treatment. We concluded that removal of grazing by sheep in these meadows did not have a substantial short-term impact on forage quality or on vole populations, but longer-term studies are needed because the composition of vegetation may change slowly in response to exclusion of herbivores.

Ecologists have long sought to identify environmental and ecological traits influencing space use by individuals. Prey availability, habitat type, conspecific interactions, and sex are cited as determinants of carnivore spatial behavior, although empirical evidence of relationships between variables and home-range size are rare. We examined the relative importance of different ecological factors on the spatial behavior of Pallas's cats (Otocolobus manul), mesocarnivores native to the montane steppes of central Asia. Between 2005 and 2007 we estimated home-range size for 9 male and 16 female Pallas's cats. Cats used large and variable home ranges, with male home ranges 4–5 times the size of female ranges. Contrary to predictions, home-range size did not increase in response to low prey availability or seasonality. Smaller home ranges were associated with higher coverage of preferred rocky habitats in the home-range center, whereas larger home ranges were associated with higher connectivity of rocky habitats in the periphery of home ranges. This suggests that space use by Pallas's cats is a function of sex and is mediated by the distribution and availability of habitats. Because of interspecific predation pressure experienced by Pallas's cats, we argue that their spatial behavior originates from trade-offs between accessing food and maintaining proximity to habitats that provide cover from predators.

Environmental change, including global warming, can lead to directional changes over time in phenotypic traits such as sex- and age-specific body mass. We evaluated the potential short-term effects of a series of hot and dry springs and early summers on mass of yearling chamois (Rupicapra rupicapra) in 2 populations in the western Alps. Yearling mass decreased in both populations over the study period, but much of this decline seemed to originate from a sharp drop in 2003, after which body mass remained low. Our analysis suggested that this decrease was caused by the additive effects of warm springs and summers over the first 2 years of life. The mass of adult chamois also decreased over time. These results suggest that ongoing warming in the Alps could be a selective pressure on the life history and reproductive strategies of wild ungulates.

In this study we combine analyses of wing morphology, echolocation calls, and temporal and spatial activity patterns to explore mechanisms of ecological partitioning among 4 syntopic Antillean mormoopids (Pteronotus macleayii, P. parnellii, P. quadridens, and Mormoops blainvillei). We captured bats with mist nets and harp traps, and monitored bat activity using automated Anabat systems for 31 nights at Sierra del Rosario Biosphere Reserve in Cuba. The wing morphologies (very low wing-loading and average-aspect ratio) and echolocation calls (broadband steep frequency-modulated calls at high frequencies) of all 4 species suggest that Cuban mormoopids are adapted to slow maneuverable flight, adequate for hunting insects by slow aerial hawking in background-cluttered habitat. However, our data show that each species has a combination of wing and echolocation call characters, presumably reflecting differences in their foraging behavior and microhabitat use. All 4 species were present at the 3 sampling sites and a majority showed similar activity rates at each site. Thus, we did not find strong evidence of spatial segregation during foraging. However, overall activity levels were higher in the primary forest when compared with 2 secondary-growth forests. Most pair-wise comparisons of temporal activity patterns between species were significant, suggesting high levels of temporal segregation. Our data suggest that wing morphology, echolocation call structure, and temporal activity patterns are morphological and behavioral factors that could facilitate resource partitioning among the Cuban mormoopid bats.

En el presente estudio combinamos el análisis de la morfología alar, las llamadas de ecolocalización y los patrones de actividad espacio-temporal para explorar mecanismos de partición ecológica entre 4 especies sintópicas de murciélagos mormópidos (Pteronotus macleayii, P. parnellii, P. quadridens and Mormoops blainvillei). Se realizaron capturas con redes de niebla y trampas arpas, y se monitoreó la actividad acústica mediante el sistema Anabat, durante 31 noches en la Reserva de la Biósfera Sierra del Rosario en Cuba. La morfología alar (muy baja carga alar y valores promedio del índice de aspecto) y las llamadas de ecolocalización de banda ancha y frecuencia modulada a altas frecuencias, sugieren que los mormópidos están adaptados para un vuelo lento y maniobrable, adecuado para utilizar hábitats estructuralmente complejos. Sin embargo, cada especie muestra una combinación de características alares y de ecolocalización, la cual presumiblemente refleja diferencias en la conducta de forrajeo y el uso del microhábitat. Las 4 especies estuvieron presentes en los tres sitios muestreados y la mayoría mostraron similares tasas de actividad en cada sitio, por lo que no encontramos evidencia de segregación espacial durante el forrajeo. Sin embargo, los niveles de actividad total fueron notablemente mayores en un sitio conservado cuando este fue comparado con 2 sitios de vegetación secundaria. La mayoría de las comparaciones pareadas de los patrones de actividad nocturna fueron significativas, lo que indica altos niveles de segregación temporal entre las 4 especies. Nuestros datos sugieren que la morfología alar, la estructura de las llamadas de ecolocalización y los patrones de actividad nocturna, son factores morfológicos y conductuales que facilitan la partición de recursos entre éstas especies.

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 (F_ST = 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.

A consequence of introduction of alien species can be hybridization with a closely related native species. Hybridization can have a large effect on the genetic structure and conservation status of native populations. Here, we present a study of hybridization and introgression between native red deer (Cervus elaphus) and introduced sika deer (C. nippon) from 5 regions in Poland, the Kaliningrad District (Russia), and Lithuania. With a set of microsatellite loci and a mitochondrial marker, we uncovered extensive hybridization in all regions despite different population dynamics and no reports of hybrid individuals. We propose that sika populations in Eastern Europe were established with individuals coming from at least 2 different localities in southern Japan and eastern China. Legislation designed to reduce threats posed by sika deer could help to prevent further hybridization.

Body growth of North Atlantic right whales (Eubalaena glacialis) was described from measurements of known-age live and dead individuals to gain insights into the nutritional needs and life-history strategies of this endangered species. Body lengths from 154 individuals revealed that calves more than doubled in size and attained three-fourths of asymptotic adult size by the time they had weaned at 12 months. Calves gained on average ∼1.7 cm and ∼34 kg per day while nursing during this extremely rapid growth phase. Mean predicted lengths and body mass were 4.2 m and 1.1 metric tons (mt) at birth, 10.3 m and 13.5 mt at weaning, and 13.6 m and 29.6 mt when fully grown. Growth of right whales was best described using a 2-phased Gompertz growth model and could not be fit using any of the single continuous growth models commonly used for other mammals. Rapid growth during dependency may minimize the risk of predation and maximize calf survival. Rapid calf growth also may maximize development of the mouth and baleen to optimize foraging efficiency of juveniles at the time of weaning, as well as improve reproductive fitness by reducing the age at which sexual maturity is attained. However, transferring the amount of energy needed to support the rapid postnatal growth of North Atlantic right whales may ultimately affect the intervals between pregnancies (>3 years) of mature females.

A new species of tuco-tuco, genus Ctenomys, is described from sandy soils on the western slopes of the state of Rio Grande do Sul in southern Brazil. This species is distinguished from other named members of this South American endemic genus by several characteristics. Diagnostic traits for this proposed species are a diploid number of 50 chromosomes and an autosomal fundamental number of 68 arms, with the 1st pair much longer than in other related species. Qualitative and quantitative (geometric morphometrics) analyses of the skull morphology and phylogenetic analysis of the mitochondrial cytochrome-b gene support species status, especially when compared with phylogenetically related and geographically neighboring species. Populations of this species have a narrow geographic distribution in a small area (∼500 km²) that has been suffering from anthropogenic pressure from soybean, pine, and eucalyptus plantations, as well as desertification. This scenario suggests that this species could be characterized as endangered.

Uma nova espécie de tuco-tuco, gênero Ctenomys, é descrita para a região de solos arenosos no oeste do estado do Rio Grande do Sul, Brasil. Esta espécie distinguiu-se das demais espécies do gênero, endêmico da América do Sul, através de diversas abordagens. O número diplóide 2n = 50 (número de braços autossômicos ou número fundamental NF = 68) com o primeiro par consideravelmente maior que outras espécies relacionadas, são características diagnósticas para a nova espécie. Análises qualitativas e quantitativas de morfologia do crânio, utilizando morfometria geométrica, bem como análises filogenéticas do gene mitocondrial citocromo b, suportam este status, principalmente em comparação com outras espécies do gênero relacionadas filogeneticamente e próxima geograficamente. Com área de ocorrência restrita à aproximadamente 500 km², esta espécie encontra-se extremamente ameaçada devido à intensa produção de soja e silvicultura na região, além de processos de desertificação. Este cenário sugere que a nova espécie seja categorizada como ameaçada.

We estimated sex- and age-specific apparent survival of harbor seals (Phoca vitulina richardii) born at Tugidak Island, Alaska, from 2000 to 2007 using mark–recapture models and photographs of ventral pelage markings to identify individuals. Estimates of annual apparent survival (1 − (mortality emigration)) of females were from 0.05 to 0.10 higher than those of males and were 0.820 for weaning (∼1 month) to 1 year, 0.865 for 1–3 years, and 0.929 at 3–7 years. Annual survival of males was 0.717, 0.782, and 0.879 for the same ages. Highest mortality occurred preweaning, with cumulative mortality to 4 weeks of age of 0.259, indicating this is the most vulnerable period for Tugidak harbor seals. Estimates of survival, not biased by misidentification, required that an individual had at least 2 good-quality, matching photographs in the photograph library. The number of photographs available for matching improved resighting probabilities from 0.43 for seals with 2 photographs to 0.69 for seals with 8 photographs, but this heterogeneity did not affect survival estimates. Survival estimates based on photograph-identification data were nearly identical to those based on resightings of flipper-tagged seals using mark–recapture models with a preliminary double-tag–loss estimate of 2.5% per year. Photograph identification of natural pelage markings provides a viable method for estimating vital rates of harbor seals even at large haul-outs (>1,000 animals) and may be useful for populations of conservation concern that require low disturbance of animals or where capturing sufficient numbers of seals for artificial marking is not feasible.

The small Caribbean island of Montserrat has been battered by several hurricanes, and beginning in 1995, pyroclastic eruptions from the Soufriere Hills Volcano have destroyed the southern portion of the island. In addition to being incinerated by pyroclastic flows (300 °C), the bats of Montserrat also have had to contend with acid rain and the deposition of volcanic ash on leaves, fruits, and flowers and its subsequent ingestion by the bats. We document a dramatic decrease in the bat population and increases in several sublethal pathologies associated with the accumulation of ash across the island coincident with the onset of volcanic activity. Before 1995, less than 1% of the fruit bats exhibited evidence of unusual tooth wear. Since 1995, fruit bats have exhibited abnormal tooth wear advanced by the ingestion of volcanic ash while feeding and grooming. Damage to the teeth often includes ablation of the entire enamel crown and the exposure of the pulp cavity. Idiopathic hair loss was practically nonexistent before 1997 but alopecia has been frequently recorded since that time in adult frugivorous bats that live within the most damaged habitats on the island. This baldness is most likely related to physiological stress, high ectoparasite loads, or possible mineral deficiencies associated with the ingestion of ash. Furthermore, we have found evidence for respiratory pathologies in Artibeus jamaicensis resulting from the inhalation of volcanic dust and ash.

Eidolon helvum is widely distributed across sub-Saharan Africa where it forms large, dense colonies. The species is migratory and satellite telemetry studies have demonstrated that individuals can migrate over 2,500 km. It is a common source of bush meat in West Africa and evidence of infection with potentially zoonotic viruses has been found in West African colonies. The species, therefore, is of interest to both ecologists and those interested in public health. Despite this, demographic parameters of the species are unknown. We focused our study primarily on a colony of up to 1,000,000 bats that roost in trees in Accra, Ghana to obtain estimates of birth rate and survival probability. Aging of bats by examination of tooth cementum annuli allowed use of life tables to indicate an annual survival probability for juveniles of 0.43 (95% confidence interval [CI] 0.16–0.77) and for adults of 0.83 (95% CI 0.73–0.93). Additionally, an annual adult survival probability of 0.63 (95% CI 0.27–0.88) was estimated by following 98 radiocollared bats over a year; capture–recapture data were analyzed using multistate models to address the confounding factor of emigration. True survival probabilities may be in between the 2 estimates, because permanent emigration may lead to underestimation in the capture–recapture study, and population decline may lead to overestimation in the life table analysis. Birth rates (0.96 young per female per year, 95% CI 0.92–0.98) and colony size changes were also estimated. Estimation of these key parameters will allow future analyses of both infection dynamics within, and harvest sustainability of, E. helvum populations.