Determinants of sex ratios in animal populations have been of general interest to ecologists for decades. We tested the hypothesis that offspring sex ratio in a population of northern elephant seals (Mirounga angustirostris) was related to large-scale environmental indices reflecting ocean climate and productivity that affected the condition of reproductive females over 31 years (1976–2006). More males were produced during years of weaker pressure differences and warmer sea surface temperature anomalies in the northeastern Pacific, conditions that reduce or disperse prey resources for gestating females in the North Pacific Ocean. For this species, sexually distinct forage resources exist, so competition for food resources occurs predominately within sex. These results are consistent with the resource competition model for facultative adjustments of offspring sex ratio. Anthropogenic global warming is predicted to warm the North Pacific. This could result in altered basin-scale ocean productivity, increased nutritional stress, and an overabundance of males that may adversely affect this and other similarly regulated mammalian populations.

Estimating survival rates of naturally hibernating mammals is important for ecological and conservation reasons, but empirical estimates are logistically difficult to obtain. Individual-based models can estimate survival under circumstances that would be impossible or unethical to test experimentally. Here, we present an individual-based model based on energy expenditure to estimate survival rates of hibernating little brown bats (Myotis lucifugus). Initial simulations assumed only thermal energetics of individuals were important to energy expenditure; subsequent simulations assumed bats also use a behavioral mechanism (clustering) to reduce energy expenditure during euthermy. Our model suggests that survival rates are high (>0.96) for populations that cluster during hibernation and experience no human disturbance, regardless of winter length (between 90 and 200 d). Survival rates are much lower, especially at long winter lengths (0.73 ± 0.01 SD at 200 d), if bats do not cluster. Human disturbances strongly affect survival rates, but the relationship is not linear. Survival rates are not lowered substantially by a limited number of disturbances because those arousals would have occurred naturally, but as disturbances reach a frequency threshold (dependent on winter length and disturbance pattern) they become very detrimental to survival. Thus, our model has implications for understanding the effect of environmental variability, social thermoregulation, and human disturbance on mammals hibernating under natural conditions.

Meadow jumping mice (Zapus hudsonius) reduce their metabolism substantially during hibernation and use stored fat reserves for overwinter energy needs. Preble's meadow jumping mouse (Z. h. preblei; PMJM) occurs along the Front Range of Colorado, north into southeastern Wyoming, and is listed as a threatened species under the Endangered Species Act because of the conversion and degradation of riparian habitats. To better understand how increasing fat and body mass before hibernation impact overwinter survival, we conducted a mark–recapture study of PMJM at the United States Air Force Academy, El Paso County, Colorado. We used environmental covariates and individual covariates, such as body mass and fat mass, to improve survival estimates. Overwinter survival of female PMJM was higher during long, cold winters, whereas overwinter survival of males was lower during winters with much snowfall. For both sexes, heavier individuals had higher overwinter survival. A combination of large body mass and colder winters may allow PMJM to conserve valuable fat resources. Because periodic arousal from hibernation is the most energetically expensive activity over winter, increasing body size (reducing surface area-to-volume ratio) should increase energy conservation and probability of survival.

High-latitude voles and lemmings undergo strong seasonal changes in their behavior and physiology, which may lead to concurrent changes in bone mineral density (BMD). We tested whether the BMD of northern red-backed voles (Myodes rutilus) in Alaska changed seasonally, and if so, whether these changes in their weight-bearing bones were correlated with seasonal changes in photoperiod (a mediator of activity and concentrations of reproductive hormones in high-latitude voles and lemmings), body mass, body length, or a combination of these. We used dual-energy X-ray absorptiometry to measure the BMD of the femur and humerus of voles collected in different seasons. BMDs increased dramatically from the start of spring to their peak level in early summer, and then decreased gradually to their lowest point in late winter. BMDs were significantly lower in fall and winter than in spring and early summer. BMDs of long bones were significantly correlated with both body mass and photoperiod, which accounted for 46.2% and 45.7% of the variation in the BMDs of femur and humerus, respectively. The strong changes that we observed in BMD are likely to be due, in part, to the combined effects of strong seasonal changes in body mass, activity, and baseline levels of reproductive hormones.

Seasonal environments favor the timing of reproduction to match seasons when successful reproduction is most likely. Most species of temperate zone mammals suppress reproduction in winter using changes in day length as a cue. In many species, individuals vary genetically in how strongly they respond to these seasonal cues. Individuals also may modify their response to day length depending upon other factors, including their age. Age-specific changes might occur because young, peripubertal rodents are more strongly affected by harsh conditions than adults, and therefore might be more sensitive to inhibitory photoperiods. We tested the hypothesis that genetic variation in responses to photoperiod persists as individuals age. Young males from a captive population of white-footed mice (Peromyscus leucopus) that is genetically variable for reproductive inhibition by short day length (SD) were tested for photoperiod responses. Mice were placed in SD within 3 days after birth, tested at age 70 days, allowed to mature for at least 18 weeks at long day length, and then tested again as adults aged ≥34 weeks. Young males were more likely to be strongly reproductively suppressed by SD than adults, indicating that age-specific changes in reproductive strategy occur in this population. However, males that were reproductively photoresponsive when young also were more likely to be reproductively photoresponsive as adults. Thus, genetic tendency for reproductive sensitivity to photoperiod is a trait retained from puberty to adulthood, but attenuates with age.

Reproductive effort should negatively correlate with reproductive value, yielding a pattern of increased effort with age. According to the terminal investment hypothesis, females near the end of their reproductive life span should devote more resources to reproduction than those near the start of their reproductive careers. We tested predictions of the terminal investment hypothesis by evaluating 38 years of reproductive life-history data collected from Nile lechwe (Kobus megaceros), an ungulate species living at San Diego Zoo's Wild Animal Park. The maximum reproductive success of Nile lechwe matched predictions of models of lifetime reproductive effort, with the relative mass of newborn calves providing an accurate indicator of the costs of reproduction. Newborn mass was significantly correlated with maternal age, and neonatal males tended to be heavier than neonatal females. Older dams were more likely to produce sons than daughters, dams that produced sons were more likely to die than were dams that produced daughters, and male calves were less likely to survive than were female calves. We conclude that young females endure a fertility cost while breeding, whereas older females encounter a survivorship cost, associated with progeny production. Our findings support the terminal investment hypothesis, and we suggest that secondary sex ratio bias among older female Nile lechwe reflects the evolution of a flexible life-history strategy promoting production of costly male calves when reproductive value is declining.

Once encompassing as many as 9 species of pocket gophers spread across most of the Mexican Altiplano, the genus Pappogeomys is now restricted to a single species, P. bulleri, occupying the mountains, tablelands, and coastal plains near the western end of the Trans-Mexican Volcanic Belt in west-central Mexico. Herein, we review the taxonomic history of Pappogeomys and examine relationships among populations of P. bulleri from throughout the geographic range of the species based on analyses of nonpreferentially stained karyotypes and mitochondrial and nuclear sequence data. Results of these analyses are concordant and reveal 3 major clades of P. bulleri that are separated by major physiographic features of the region, including the Sierra Madre del Sur and drainages of the Río Grande de Santiago, Río Ameca, Río Ayuquila, and Río Armería. We reduce the number of subspecies of P. bulleri from 9 to 5 valid forms and provide a revised synonymy of the species.

A new species of horseshoe bat (Chiroptera: Rhinolophidae) is described from southwestern China. The presence of a wedge-shaped sella and pointed connecting process of the nose leaf aligns the new species to the landeri group in the Afro-Palearctic lineage of Rhinolophus. However, the new species is distinctly separable from these allopatrically distributed species by its noticeably larger body size. Other sympatric large-sized species of Rhinolophus have rounded connecting processes. Molecular systematic analyses based on mitochondrial cytochrome-b sequences confirmed the affinity of the new species to the Afro-Palearctic lineage, but in a clade most closely related to the ferrumequinum, fumigatus, and maclaudi groups. Of these species, only R. ferrumequinum ranges into Asia and overlaps in distribution with the new species. R. ferrumequinum is similar in general body size and external appearance; however, the new species is distinct in the characteristics of the nose leaf, skull, and baculum. The presence of a new species from southwestern China in the Afro-Palearctic lineage indicates a more complex historical biogeographic scenario within Rhinolophus than previously known. The difficulties found in allocating the new species to one of the phenetically described traditional species groups stress the convenience of using a phylogenetically based systematic organization of the genus Rhinolophus.

The cause of extinction of the noble marten (Martes americana nobilis), as well as its taxonomic position, has been the subject of debate in recent years. This extinct marten, a close relative of the extant American marten (Martes americana), is known from 18 sites in western North America, most dating to the late Pleistocene. Because boreal fauna were associated with the late-Pleistocene noble marten, researchers generally believed that it inhabited boreal forests like the American marten, and competition between the 2 may have caused its extinction. Recent discoveries of noble martens associated with xeric fauna from Holocene contexts have called these assumptions into question. I explore the adaptation and habitat of the noble marten with an analysis of its faunal associations and find-site locations. The analysis suggests that the noble marten was adapted to open, mesic grasslands in montane foothills, and was likely not sympatric with the American marten. I also introduce a new Holocene noble marten specimen, a right mandible dating to 6,400 years ago, from Mummy Cave, an archaeological site in northwestern Wyoming.

We studied the population structure, spatial patterns, and activity patterns of the water opossum (Chironectes minimus) via capture–mark–recapture and radiotelemetry from October 2004 to October 2006 in Atlantic Forest streams in southeastern Brazil. We tested the hypothesis of reproductive seasonality, the usual pattern in neotropical marsupials, by examining recruitment of juveniles. The hypothesis was rejected, supporting the alternative hypothesis that breeding by water opossums was better explained by its habitat characteristics and prey availability than by its phylogenetic ancestry. The observed sex ratio was significantly biased toward males. The home lengths of individual water opossums varied from 844 to 3,724 m. Males had larger home lengths than females, and there were male–male and male–female overlaps. The longer home lengths for males may explain the observed sex ratio bias, because males are more exposed to capture. All individuals used stream stretches with preserved riparian forest, fast-flowing water, and stony substrate. The hypothesis that activity was homogeneously distributed throughout the night was rejected; activity began right after sunset and ended before sunrise, but with higher levels of activity in the first 6 h of the night. Because of anthropogenic alterations of hydrographic basins, water opossums may be threatened by reduction of their main habitat, streams with fast-flowing water and stony substrate.

Didelphid marsupials specialized in arboreal locomotion have morphological features convergent with primates, and hence are an ideal group to test hypotheses about the evolution of arboreality. We analyzed the relative contributions of allometric, phylogenetic, and adaptive aspects to the climbing performance of 7 species of didelphid marsupials of the Atlantic Forest of Brazil. These species encompass a diversity of body sizes, use of the vertical strata, and lineages within didelphid marsupials. Climbing performance was evaluated by measuring the velocity in climbing 3 nylon ropes of 0.6, 0.9, and 1.25 cm diameter. The cycle of maximum velocity was chosen to measure relative stride length, frequency, and relative velocity. As expected, arboreal species (Gracilinanus microtarsus, Marmosops incanus, Micoureus paraguayanus, and Caluromys philander) had higher relative climbing velocities than more terrestrial species (Didelphis aurita, Philander frenatus, and Metachirus nudicaudatus). Stride frequency was mostly associated with phylogeny and vertical use of the forest, but relative velocities generally were determined by a combination of stride length and frequency. Differences in climbing performance originated early in the diversification of the group, but continued to evolve because significant differences also were detected at the subfamily, tribe, and genus levels, which seems to parallel the evolution of grasping abilities in primates.

Wild pigs (Sus scrofa) are considered opportunistic omnivores that consume primarily plant matter; vertebrates are thought to constitute only a minor component of their diets, primarily as carrion, but active predation on vertebrates has been suspected. We examined the stomach contents of 104 wild pigs collected during a 7-year period in oak woodlands of the Diablo Range, California, and found that 40.4% contained vertebrate prey comprising 20 species, including 11 mammals, and totaling 167 individuals. Most stomachs with vertebrate prey included multiple individuals (≤18) of >1 species (≤6). Predation occurred in both male and female pigs and was most frequent during summer and fall, probably in response to protein deficiency in the diet. Wild pigs are a conservation concern because of their rooting behavior and consumption of mast; our results extend their potential impact to include predation on vertebrates, especially small mammals.

The introduction of a species into an ecosystem with species already occupying a similar trophic level is predicted to lead to a high degree of niche overlap. The feral pig (Sus scrofa), one of the world's worst invasive species, was introduced to the Pantanal about 200 years ago and is thought to compete with the native white-lipped peccary (Tayassu pecari) and collared peccary (Pecari tajacu). Resource partitioning between the 3 species was examined, including analysis of fruit items and plants in fecal samples as well as encounter rates in different habitats, to help generate hypotheses about competitive interactions among the species. Overlaps in food resources and habitat use between feral pigs and peccaries were found to be lower than expected. In fact, niche overlap was highest between the native species. Results indicate that currently, feral pigs are not a direct threat to the native peccaries in the study area. Differences in morphology and behavior indicate possible mechanisms of niche partitioning between the species. Feral pigs may, nevertheless, impact the wildlife community in other ways as predators of eggs, by destruction of vegetation through rooting, or by functioning as disease reservoirs. Cattle-ranching activities may favor feral pigs and the current anthropogenic changes in the landscape could lead to changes in competitive dynamics between feral pigs and native species.

Bobcats (Lynx rufus) are valuable indicators of connectivity in the highly fragmented landscape of coastal southern California, yet their population sizes and densities are largely unknown. Using noninvasive scat sampling in a capture–recapture framework, we estimated population sizes for 2 similar areas of natural habitat with differing levels of isolation by human development in Santa Monica Mountains National Recreation Area, California. We used scat transects with geographic information system land-use layers and home-range sizes of bobcats to estimate effective sampling area and population densities. Estimates of population size in the study area connected to a much larger habitat area (26–31 individuals) were similar to estimates for the area that was completely surrounded by development (25–28 individuals). Bobcat densities for the 2 study areas also were similar (ranging from 0.25 to 0.42 bobcat/km²) and likely represent recent population declines because of notoedric mange likely interacting with toxicants. These methods proved effective despite particularly low densities of bobcats and may be especially useful when study areas are geographically isolated, reducing the uncertainty in size of the sampling area.

There is widespread evidence that feeding ecology can lead to differences in mammalian social systems. To understand how diet and ecology affect the social behavior of ring-tailed coatis (Nasua nasua), detailed measures of feeding behavior were recorded from 2 well-studied groups over a 2-year period. The proportion of fruit and invertebrates in the diet of ring-tailed coatis in Iguazu, Argentina, was very similar to that in diets of white-nosed coatis (N. narica) and ring-tailed coatis studied at field sites in Brazil. Consumption of vertebrates in Iguazu was exceptionally rare. The proportion of time spent foraging for invertebrates and fruit generally matched seasonal changes in the abundance these foods in the environment. During the winter, when invertebrate and fruit availability was low, coatis spent a large amount of time feeding on 2 exotic fruit species. The presence of exotic fruits provided coatis with food during the lean winter season and may have influenced the high reproduction and survivorship found in this population. Coatis spent about 44% of their fruit-foraging time exploiting pindo palm (Syagrus romanzoffianum) fruits and it appeared that this fruit species played a major role in shaping the ranging and feeding behavior of coati groups. The time spent foraging at fruit trees and the total number of fruits eaten varied depending on the species of tree. Coati groups spent an average of 2.5–12.5 min feeding on different species of fruit trees, and coati groups ate an average of 2.6–269.8 fruits per tree species. The quick depletion of fruit trees and high density of foraging individuals, especially when feeding on pindo, plays an important role in shaping the social system of coatis.

We examine foraging behavior of coastal black bears (Ursus americanus kermodei) during different light regimes on a salmon stream in British Columbia, Canada (2000–2002). Bears (maximum 7 simultaneously) were primarily active during daylight near the onset of the salmon spawning run and shifted to twilight and darkness as the spawning run progressed. Overall time budget included search and pursuit (58%), handling and ingestion (38%), and agonistic interactions with other bears (4%). Scavenging was greatest during daylight (19%) and lowest during darkness (3%). Bears were most efficient at capturing live salmon when standing (35.4% success) followed by running (20.5%) and walking (15.2%). Highest capture efficiency occurred during twilight (33.6%) compared with daylight (26.5%) and darkness (24.7%). Capture rate ranged from 1 to 3 salmon per hour per bear. Our results suggest that bears increased their total salmon intake by alternate use of visual and auditory cues during daylight and darkness.

The maned wolf (Chrysocyon brachyurus) is the largest canid in South America, weighing up to 30 kg, and exhibits an omnivorous diet based on fruits and small vertebrates. Maned wolves are considered to live in monogamous pairs defending a common territory, with mates living a largely solitary life, but these conclusions come from few studies with small samples. We captured maned wolves in Emas National Park, central Brazil, and monitored their use of space using radiotelemetry. Home-range size and overlap of 45 adults, and interactions between members of 5 pairs, were investigated. Home-range sizes of resident adults averaged 80.18 km² using the fixed kernel with 95% of the locations, and averaged 13.78 km² with 50% of the locations. Overlap of 95% ranges between male–male, female–female, or mixed dyads was similar, approximately 0.20, whereas 50% ranges of maned wolves showed less overlap overall but more tolerance for overlap with the opposite sex. Members of a pair were located alone more often than together, and even when located simultaneously maintained a mean distance of >0.5 km apart, independent of time of day. Results are in agreement with a spatial organization based on monogamous mating pairs with little intrapair sociality, but the latter needs to be investigated in more detail.

Apart from the alerting function of alarm calls, selection may favor cues that help individuals to distinguish between reliable and unreliable callers. However, this mechanism for selective response to real and false alarms may act only if the individual characteristics of the call are stable at least for some time. Here we test this implicit assumption for the caller's reliability hypothesis, studying individuality of alarm calls in a colony of free-living, individually marked speckled ground squirrels (Spermophilus suslicus). We recorded each of 20 study animals 4 times during repeated captures when calling from a live trap toward a human, with spans of 1 day, 2 weeks, and 1 year from the 1st capture. Ten alarm call notes per animal per capture were analyzed. Individual alarm call notes showed high similarity within captures but differed strongly between captures. Both multivariate analysis of variance and discriminant function analysis showed that vocal individuality decreased rapidly with an increase of the time span between recordings. However, vocal individuality always remained higher than expected random value. Examination of our data suggests that alarm calls are unstable, which contradicts the caller reliability hypothesis, because its implicit assumption of stable individual identity is not fulfilled. However, short-term stability still may be sufficient to ensure short-term individual recognition between kin and neighbors. Also, even if the alarm calls change structurally, because group members meet up daily, they can update their knowledge of the call structure of individuals, and this would likely allow them to distinguish between reliable and unreliable individuals.

In communities where strong interspecific competition between native species is lacking, exotic and native species often exhibit intense resource competition resulting in decline of native populations. We examined the potential for interspecific competition for nest sites between co-occurring native Mt. Graham red squirrels (Tamiasciurus hudsonicus grahamensis) and exotic Abert's squirrels (Sciurus aberti) in the Pinaleño Mountains of Arizona. Comparison of nest use between red and Abert's squirrels at different scales (nest, nest tree, and nest site) revealed contrasting results. Competition for nests and nest trees appears unlikely given the dissimilarity in use of nest types and tree characteristics. Abert's squirrels predominately used dreys, whereas red squirrels mostly used cavity nests. Neither squirrel species occupied a nest used by the other species. Nest trees differed in size and species between squirrels for dreys, but not for cavities. Abert's squirrel nest sites were found in a wider range of microhabitats including almost all microhabitats in which red squirrel nest sites were located. Although there was significant overlap, each species showed distinct trends in microhabitat. In general, red squirrel nest sites were characterized as more densely forested areas dominated by corkbark fir (Abies lasiocarpa var. arizonica), whereas Abert's squirrel nest sites were more open and contained greater tree species diversity. Overlap in microhabitat characteristics increases the likelihood of interspecific competition and could increase the vulnerability of red squirrels to extinction.

Severe disturbance may alter or eliminate important habitat structure that helps preserve food caches of food-hoarding species. Recent recolonization of an insect-damaged forest by the endangered Mt. Graham red squirrel (Tamiasciurus hudsonicus grahamensis) provided an opportunity to examine habitat selection for midden (cache) sites following disturbance. From September 2003 to December 2005, we examined surface temperature and physical and vegetative characteristics associated with random locations and midden sites in insect-damaged forests. Red squirrel use of midden sites that are similar in structure to those used before insect infestation indicates that insect infestation did not eliminate midden habitat. However, differences between occupied middens and historical middens that are unoccupied reflect the severity of insect infestation tolerated by red squirrels. Occupied middens had <64% tree mortality, high basal area of live trees, and cooler surface temperatures during snow-free months. Forest areas with greater tree mortality would likely not represent habitat, threatening the persistence of an isolated population. Although conservation efforts can protect remaining habitat, disturbance events continually represent a threat. Habitat loss and predictions of increased disturbance due to climate change highlight the importance of documenting response to disturbance.

This study examined habitat use and diet composition of Norwegian lemmings (Lemmus lemmus) and field voles (Microtus agrestis), which occur together and potentially compete for resources in alpine areas of central Norway. Both species preferred habitats rich in herbaceous monocots and dicots and willow (meadows and willow meadows). However, lemmings spread into other habitats, particularly lichen heath, when populations were high. Lemmings showed a clear preference for monocots in their diet, eating mostly sedges (Carex and Eriophorum), whereas voles had a much more diverse diet that included equal amounts of, and more species of, monocots and dicots. Because relatively little overlap occurred either in habitat use (33–57%, increasing overlap with lower densities of lemmings) or in diet (30–51%), and because lemming populations were usually low, exploitative competition between the 2 species seemed unlikely. Nevertheless, aggressive interspecific interactions during occasional years with high lemming densities could still negatively influence populations of field voles.

Southeastern Brazil has seen dramatic landscape modifications in recent decades, due to expansion of agriculture and urban areas; these changes have influenced the distribution and abundance of vertebrates. We developed predictive models of ecological and spatial distributions of capybaras (Hydrochoerus hydrochaeris) using ecological niche modeling. Most occurrences of capybaras were in flat areas with water bodies surrounded by sugarcane and pasture. More than 75% of the Piracicaba River basin was estimated as potentially habitable by capybara. The models had low omission error (2.3–3.4%), but higher commission error (91.0–98.5%); these “model failures” seem to be more related to local habitat characteristics than to spatial ones. The potential distribution of capybaras in the basin is associated with anthropogenic habitats, particularly with intensive land use for agriculture.

We investigated the social organization of Bonin flying foxes (Pteropus pselaphon) in a roost and the seasonal shift of roosting sites in relation to the reproductive cycle on Chichi-jima Island, Ogasawara (Bonin) Islands, Japan. Using radiotracking, we found that flying foxes formed a colonial roost in a specific area of the island during winter and were more widely dispersed in summer. Although summer roosts were used by solitary flying foxes or nursing females, the winter roost consisted of about 100 individuals. Flying foxes formed ball-shaped, dense clusters in the winter roost. We found 6 roosting groups of clustered bats classified into 3 groups in relation to sex and age: 1) multiple females with a few males, 2) multiple males, and 3) subadults of both sexes. Copulation attempts were not observed in the summer roosts but frequently were observed in type 1 groups in the winter colonial roost. Based on the emergence of newly born pups and the estimated period of pregnancy, fertilization is likely to occur in the winter colonial roost. We conclude that the winter colonial roost plays an important role as a mating site.

Although bats are well known for their use of ultrasound for echolocation, there is limited evidence for its use in a social context. We tested whether ultrasonic vocalizations in bats were contextually (roosting or flying) sexually dimorphic. During the reproductive season, we recorded ultrasonic signals of captive adult male and female big brown bats while the bats were flying on tether lines in the field, and compared these signals to ultrasonic vocalizations made while roosting in an anechoic chamber. Principal component analysis reduced 7 ultrasonic call descriptors to 2 components that related to frequency (PC1) and time or shape (PC2). While bats were roosting, ultrasonic call components related to time or shape and frequency were both sexually dimorphic, being increased in males in each instance. However, when bats were recorded while flying, these same call components were no longer sexually dimorphic. This finding suggests that bats are changing their ultrasonic calls in relation to functional context, making them monomorphic and utilitarian for activities such as foraging and navigation, but dimorphic in a situation when mating activity is likely.

Ecological assessments of the effects of anthropogenic change often focus on species richness or species abundances. Nonetheless, changes in behavior (e.g., activity patterns) may provide equally important insights into responses to disturbance that have conservation or management implications. Because many neotropical bats provide critical ecosystem services, their responses may be of particular conservation concern. We evaluated the effects of season and habitat conversion on temporal activity patterns of 8 abundant species of frugivorous bats in lowland tropical rain forest of Iquitos, Perú. Season had little effect on activity patterns of any species of bat. Five species exhibited different activity patterns in primary or secondary forest compared to agricultural habitats. No interspecific differences in activity patterns occurred in primary forest. In agricultural areas, the patterns of activity of Carollia benkeithi and Rhinophylla pumilio were distinct from those of other species. In secondary forest, activity patterns of Artibeus lituratus and R. pumilio were distinct from those of other species. Temporal activity patterns of common frugivores overlapped more than expected by chance, regardless of season or habitat. Neotropical frugivores avoid open areas during twilight to reduce risk of predation. Nonetheless, to meet their considerable minimum daily caloric intake requirements, frugivores forage throughout most of the night. Increased habitat fragmentation may effectively reduce foraging times and subject bats to increased risk from predators during twilight and periods of great lunar illumination, when bats avoid open areas.

Keen's myotis (Myotis keenii) has one of the most limited geographic distributions of any species of bat in North America. Because there is little knowledge of its roosting ecology, we examined selection of day-roosts in trees by male and female Keen's myotis at 3 spatial scales (tree, tree plot, and landscape) on Prince of Wales Island, southeastern Alaska, from May to September 2006. We selected variables known to influence roost selection by other tree-roosting bats for logistic regression models. We used Akaike's information criterion to rank all models within and between scales according to their ability to differentiate between characteristics of used and available roosts and we determined the effect of each variable with model-averaged coefficient estimates and associated odds ratios. We tracked 13 females and 6 males to 62 and 24 roosts in trees, respectively. Selection of day-roosts by males and females was most strongly influenced by characteristics of trees. The odds a tree was used for roosting by female Keen's myotis increased with the presence of defects, increasing diameter, and decreasing bark; increasing quadratic mean diameter in the tree plot; and decreasing distance to the nearest stream and increasing proportion of old growth in the landscape. Male Keen's myotis exhibited flexibility in types of roosts chosen, but the odds of a tree being used increased with decreasing bark, the presence of defects, and increasing slope-height. The odds a tree was used as a roost by males also increased with the increasing proportion of trees in early to late decay stages in the tree plot. Some habitat features differed between males and females at each spatial scale and differences are likely a reflection of the energetic demands associated with reproduction. We suggest that maintaining structural components characteristic of old-growth rain forest will promote conservation of Keen's myotis in southeastern Alaska.

Sexual segregation during the breeding season is common in many temperate bat species, and may be related to sex-specific thermoregulatory, microclimatic, or energetic requirements. We compiled capture data for 3 species of Nyctalus (noctule bats) obtained over >20 years to study reproductive and migratory strategies of these species in southwestern Europe. Within the Iberian Peninsula, several different strategies regarding sex distribution and migratory behavior were observed within each of the 3 Nyctalus species. In the northern part of Iberia there are populations of the 3 species composed of males all year-round with females appearing only during the mating season. Reproduction by females in this area has not been confirmed. In central and southern Iberia there are breeding populations in which sexual segregation occurs only at the roosts or at a regional scale, possibly with females located at lower elevations during the breeding season. Female-biased, long-distance migration is likely to be the cause of sexual segregation in populations of N. noctula and N. leisleri in northern and central Iberia, but not of N. lasiopterus, absent in central Europe. For this latter species, segregation by elevation also could occur in northern Iberia. The Iberian Peninsula is a good example of how breeding strategies and migratory behavior in bats can be very flexible and vary across relatively small geographical scales.