Mammalian predation influences waterfowl breeding success in the U.S. northern Great Plains, yet little is known about the influence of the landscape on the ability of predators to find waterfowl nests. We used radiotelemetry to record nightly movements of red foxes (Vulpes vulpes) and striped skunks (Mephitis mephitis) in two 41.4-km² study areas in North Dakota. Study areas contained either 15–20% grassland (low grassland composition) or 45–55% grassland (high grassland composition). Grasslands included planted cover, pastureland, and hayland. We predicted that the type and composition of cover types in the landscape would influence both predator movement across the landscape (as measured by the fractal dimension and displacement ratio) as well as localized movement (as measured by the rate of movement and turning angle between locations) within patches of different cover types. Red fox movements were straighter (lower fractal dimensions and higher displacements) across landscapes with a low grassland composition, indicating directed movement between the more isolated patches of planted cover. Striped skunk movements did not differ between landscape types, illustrating their movement along wetland edges, which had similar compositions in both landscape types. The high variability in turning angles by red fox in planted cover and pastureland in both landscape types is consistent with restricted-area foraging. The high rate of movement by red foxes in planted cover and by striped skunks in wetland edges suggests that spatial memory may influence movement patterns. Understanding the behavior of predators in fragmented prairie landscape is essential for managing breeding habitat for grassland birds and for predicting the spatial and temporal dynamics of predators and their prey.

We tested whether differences in composition and nutrients of diet explained higher density of Peromyscus aztecus in mature cloud forest and higher density of Reithrodontomys fulvescens in disturbed cloud forest. P. aztecus ate dicot leaves, stems, fruit, and seeds in mature cloud forest and dicot leaves, stems, and seeds, and monocot seeds and insects during the dry-hot season in disturbed cloud forest. R. fulvescens ate dicot leaves, stems, fruit, and seeds in mature cloud forest but monocots and insects during the hot season; dicot leaves, stems, and seeds were eaten in disturbed cloud forest. The diet of P. aztecus contained more protein and soluble carbohydrates in disturbed cloud forest where rodent density was lower; the diet of R. fulvescens contained more protein, lipid, soluble carbohydrate, Na, Mg, and P in mature cloud forest where density was lower. Nutrient differences resulted from R. fulvescens eating more monocots and dicot fruit, P. aztecus eating more monocot seeds and less dicot fruit, and both species eating more insects. Differences in composition or nutrient content of diet did not explain between-habitat differences in demography because nutrients in diet were higher in habitat of lower rodent abundance, suggesting other factors must be considered.

We examined effects of food and den site supplementation on population dynamics of Glaucomys sabrinus and Tamiasciurus douglasii in mature second-growth forests in British Columbia, Canada. We tested the hypothesis that populations of these squirrels were limited by abundance of food, not den sites. Populations were sampled intensively from June 1996 to March 1999 on controls and grids supplemented with food, food and nest boxes, and nest boxes. Analysis of variance revealed no differences in movement, abundance, recruitment, body mass of males, and percentage of males breeding among treatments for G. sabrinus or T. douglasii. Survival of G. sabrinus was not significantly different during pretreatment, but was significantly higher on grids supplemented with food during posttreatment. Occupancy rate of nest boxes in stands supplemented with nest boxes and food was 6- to 12-fold higher than in stands supplemented with nest boxes only. G. sabrinus occupied the majority of the nest boxes. We concluded that G. sabrinus used nest boxes readily but their populations were not limited by availability of den sites; availability of food appeared to have a significant effect on their populations. T. douglasii was not limited by availability of food or den sites during our study.

We tested hypotheses about factors likely to influence movements of prairie voles (Microtus ochrogaster) and meadow voles (M. pennsylvanicus) between habitat patches that differed in availability of high-quality food and amount of vegetative cover. More emigration (per capita) occurred from low-quality habitats than from high-quality habitats. A greater proportion of emigrants from high-quality habitats returned to home habitats than did those from low-quality habitats. More emigrant prairie voles moved toward habitats with supplemental food, and more emigrants moved toward the nearest receiving habitat. Prairie voles (a monogamous species) showed greater than expected permanent emigration by subadults, whereas meadow voles (a promiscuous species) showed greater than expected permanent emigration by males. These patterns largely support predictions from evolutionary theories of dispersal. Emigrating female voles, but not males, selectively settled in habitats with supplemental food, which supports the hypothesis that females respond to resource availability but males respond to availability of females. Overall, movement patterns reported here and density-dependent declines in fitness reported previously indicate that movements across habitat boundaries tend to equalize fitness of residents in habitats of different quality, consistent with the hypothesis that voles have an ideal-free distribution across habitats.

Because natal dispersal affects both individual fitness and population persistence, it is important to understand how dispersers are affected by habitat heterogeneity. To explore the effect of habitat on dispersal, we compared the ecology and natal dispersal of red squirrels (Tamiasciurus hudsonicus) originating from mature forest and adjacent commercially thinned forest. Because individuals living along the edge between the 2 forest types were more likely to have experience in both habitats, we classified squirrels according to habitat type (mature or thinned) and position (edge or deep within forest). Using livetrapping and radiotelemetry, we compared 4 habitats in terms of juvenile settlement patterns, surrogate measures of fitness, and population demography. Mature forest appeared to represent the highest quality habitat: mean density, mean overwinter survival, probability of surviving the field season, and success at raising ≥1 juveniles to emergence were higher in mature forest. However, the majority of juveniles from all habitats settled close to their natal territory, and with the exception of juveniles living along the edge of mature forest, juveniles settled within their habitat of origin. Juveniles living along mature edge biased their settlement for deep within mature forest. It appears that dispersal outcomes were affected by a combination of experience and opportunity. There are few, if any, other studies that have simultaneously compared demography, dispersal movements, and settlement patterns across contrasting habitats. While rare, studies such as this that link individual behavior and population theory are vital to effective population and landscape management.

Significant changes in local climate and correlated changes in non mammalian vertebrate populations have been documented in the Monteverde cloud forest in the Tileran Mountains of northern Costa Rica, leading to the prediction that corroborative changes should occur in bat populations. Habitat changes resulting from development for ecotourism, including a 19% increase in forest, might also be expected to impact bat populations. Analysis of data collected between 1973 and 1999 in Monteverde supports the hypothesis, although changes are less dramatic than those shown for birds, reptiles, and amphibians in earlier studies. Capture rates did not change significantly during the 27 year sample period, but relative species abundance increased, and at least 24 new species (of mostly lowland distribution) were recorded in the study area during the 1980s, 1990s, and through early 2002. These changes are likely a consequence of climatic change following global warming, forest clearing, and an increase in amount of secondary forest. This latter factor is a result of changes in land use due to development for tourism.

Three free-living female European roe deer (Capreolus capreolus L.) were fitted with a telemetry implant to measure heart-rate. Observations of behavior of undisturbed deer were made during daylight from 12 February to 12 September 1996 in the Hestehave Forest (185 ha), Kalø, Denmark. Behaviors were classified in 14 different categories. Heart rate (HR, in beats/min) in 10-s intervals was characterized by the mean HR, short-term, long-term, and overall HR variation within an observation period as well as the autocorrelation of mean HR and short-term variability. A statistical model described 90.1% of the observed variation in HR and included 4 parameters: category of behavior, Julian date, deer age, and wind speed. From 11 April to 4 August, HR is described by a tandem cosine curve with a peak on 6 May. In contrast, HR variability (short-term, long-term, and overall variability) was constant throughout the year. HR increased by 0.36 beats/min each time wind speed increased by 1 m/s, and HR variability was also positively affected by the wind speed. HR and HR variability was highest for locomotive behaviors, medium for standing behaviors, and lowest for bedded behaviors. Autocorrelation of mean HR and short-term variability was not significantly affected by any of the observed variables. Using mean HR and HR variability, it was possible statistically to distinguish 10 categories of behavior ranging from bedded with closed eyes (60.5 beats/min) to fleeing (254.8 beats/min).

We studied seasonal activity patterns and feeding behavior of a population of Finlayson's squirrel (Callosciurus finlaysonii) native to Indochina and introduced into Italy. Squirrels spent the majority of active time foraging, switching between resources according to availability. In winter, they fed mainly on buds or stripped bark, shifting to flowers when plants bloomed in spring, and to mature seeds and fruits from June to October. By November–December, bark-stripping became progressively more important. This activity accounted for 36.5% of the yearly feeding time. The flexibility to exploit a wide range of foods, the ability to change food habits throughout the year, and hoarding behavior are factors that could indicate a proclivity to use different habitats successfully.

Small day-active endotherms living in hot environments maintain heat balance and avoid overheating by behavioral adjustments of their time budgets. We examined the temporal and spatial microstructure of surface activity bouts in the degu (Octodon degus) under maximal, summertime environmental heat load in a thermally complex habitat mosaic of sun and shade. The degu is the only native small mammal regularly active during the day in central Chile. We recorded thermal environmental data and activity of individuals with video cameras to quantify time spent in open sun as compared to shade. We predicted that individuals would adjust activity “microbouts” (successive momentary movements in and out of shade cover) in response to increasing heat load. As heat load increased toward end of morning, the proportion of total surface time spent in shade increased and approached 100%. Likewise, direct exposures to solar radiation decreased from almost 8 min in early morning to less than 1 min by late morning. Field measurements of body temperature remained within a 24-h range of 36–38°C (mean 36.7°C), suggesting an intolerance of increases above this range. The low heat tolerance of the degu seems to be a physiological limitation associated with its nocturnal family lineage. Because daytime activity is exceptional within this lineage, the degu has used behavioral adjustments to become the only regularly day-active native small mammal in its environment.

Captive male Neotomodon alstoni exhibit paternal care. We tested whether presence of the male in the nest during the postpartum and weaning periods affect maternal care and promoted survival and growth of the offspring. For captive N. alstoni pairs (n = 10) both parents were maintained in the nest until weaning of the young, and in another 10 pairs the male was removed shortly after birth of young. The presence of the male had a negative impact on the time spent by females in huddling with nursing young. In the presence of the male, females groomed and sniffed young less frequently than did females rearing young in the absence of the male. Survival of offspring (84%) and their growth (20.6 ± 4.7 g) was significantly higher when both parents reared their young. Males provide additional care of young, allowing a higher quality of care by the female during rearing.

The structure of echolocation calls, and the distance over which bats perceive their environment, varies with the amount of structural clutter through which they are flying. Clutter and species had significant effects on the frequency-time characteristics of search-phase echolocation calls of northern long-eared (Myotis septentrionalis) and little brown bats (M. lucifugus). We tested an a priori derived model that predicted the pattern of differences in echolocation call variable values among clutter categories would provide insight into the relative maximum distances that bat species could perceive using echolocation. Specifically, the model predicted that species adapted to flying and foraging in cluttered habitats would have a shorter maximum perceptual distance than species adapted to flying and foraging in uncluttered habitats. The results supported this model and suggest the clutter-adapted M. septentrionalis had a shorter maximum perceptual distance than M. lucifugus, a species known to forage in a variety of habitats but mainly in uncluttered areas (i.e., over water). Using calls as the sampling unit, a neural network correctly classified >94% of the echolocation calls to species in high clutter. In medium and low clutter, >82% of the calls were correctly classified to species; however >90% correct classification was achieved by leaving <30% of calls unclassified. Researchers should develop clutter-specific call libraries to improve species classification accuracy for echolocation calls.

Ultrasonic vocalizations of infant rodents are used in developmental studies and for investigating the effects of drugs or environmental pollutants. Few studies, however, have analyzed the frequency characteristics of these ultrasonic vocalizations. This study investigates the physical and vocal development of infants (1–14 days old) of the short-tailed field vole, Microtus agrestis, under 2 conditions of isolation: at 23°C immediately after being isolated from the nest or at 23°C after 10 min of isolation at 27°C. Seventy-three percent of the infants vocalized, and there was great variation among calling infants in the number of vocalizations emitted. More infants, especially males, called during the 2nd period of isolation than during the 1st, and latency to call increased with age in males. The ultrasonic vocalizations were comparable to those recorded from North American voles. Vocalizations were classified into 7 categories on the basis of characteristics of the fundamental frequency. Simple calls were emitted most commonly and became more frequent in older infants, whereas the proportion of calls with a down-sweep in frequency and audible clicks decreased with age. The emission of ultrasonic calls, therefore, appears to reflect changes both in physical development of the infants and in their external environment.

The middle ear of the solitary subterranean rodent Ctenomys talarum was studied. The most significant features observed were the enlarged middle-ear cavity, a round and larger eardrum without pars flaccida, no connection between malleus and the tympanic bone, partial fusion of malleus with incus, a nearly flat stapedial footplate, absence of stapedial artery, reduced tensor tympani, and absence of stapedial muscle. Some of these features are shared with unrelated subterranean rodents like Spalax ehrenbergi and geomyids, possibly as adaptations for low-frequency hearing.

Gait repertoires of the northern brown bandicoot, Isoodon macrourus, were studied over a wide range of locomotor speeds. At low relative speeds, bandicoots used symmetrical gaits that included pacing, trotting, and lateral sequence strides. Forefoot contact duration was generally shorter than hind foot contact duration at all speeds. At moderate relative speeds bandicoots used half-bounding gaits with either no period of suspension or with a short gathered suspension. At high speeds the predominant gait had both a short extended and a short gathered suspension, although some strides comprised only an extended suspension. Increases in speed were accompanied by increases in spinal extension, presumably leading to the extended suspensions. On a stationary treadmill individuals occasionally used a bipedal gait. Maximum half-bounding speeds appear to be relatively low in this species.

The leopard, Panthera pardus, occurs on Java, Indonesia, but is absent from Sumatra and Borneo, the islands that lie between Java and the rest of the leopard's geographic range. Recent molecular research has suggested that Javan leopards are a distinct taxon that split off from other Asian leopards hundreds of thousands of years ago, which raises the question of how the species arrived on Java but apparently bypassed Borneo and Sumatra. I have further investigated this issue by linking the results of a morphometric analysis of 121 leopard skulls to my palaeoenvironmental reconstructions for the region. The results suggest that the Javan leopard is craniometrically distinct from leopards from the rest of Asia. I hypothesize that in the Middle Pleistocene (about 800 × 10³ years ago) leopards migrated to Java from South Asia across a land bridge that bypassed Sumatra and Borneo. During the last glacial maximum, when Java, Borneo, and Sumatra were connected, leopards could not survive on either Borneo or Sumatra because of the islands' relatively low ungulate biomass and competition from other large carnivores that were better adapted to tropical evergreen forest habitat.

The skull morphology of black bears inhabiting 2 distributional ranges isolated by 2 river basins in northern Japan was compared in order to examine whether the animals represent different populations. We found substantial differences in relative width of the skull and measurements related to the masticatory apparatus, especially in the length of the molar row and palatal width; the former already differs at 1 year of age when the eruption of permanent teeth occurs, suggesting a genetic basis for the difference. Jackknifed classification was able to correctly assign all adult specimens except 1. The results indicate that bears from these 2 areas belong to different populations that might have been isolated for a considerable period, and gene flow between them is limited, even though the distance between the 2 ranges is only several kilometers at the narrowest point. The Japanese black bear might live in small, isolated local populations.

Molecular analysis of cytochrome b (about 1,100 base pairs) in Brazilian Thrichomys specimens from Pantanal, Caatinga, and Cerrado confirmed the monophyly of this genus in neighbor joining, maximum parsimony, and likelihood analyses. Molecular and karyotypic analyses suggested that T. pachyurus (2n = 34), T. inermis (2n = 26), and Thrichomys sp. nov. (2n = 30) belonged to different evolutionary lineages. The grouping of T. apereoides populations with different karyotypes (2n = 28, FN = 52 or 50; 2n = 30, FN = 54) was difficult to explain unless by postulating a recent karyotypic differentiation and/or random extinction of lineages of an ancestral population in which the mitochondrial DNA polymorphism was present.

Results of recent molecular studies cast doubt on the validity of the superorder Archonta, suborders Megachiroptera and Microchiroptera, and infraorder Yinochiroptera and has even led some to consider novel alternatives for the evolution of flight and echolocation in mammals. At present, higher-level relationships within Chiroptera still is without consensus, and much of this controversy is related to how bats are related to other mammals and also to relationships among family-level lineages within Chiroptera. Although this controversy superficially manifests itself as differences in the relative merits of morphologic versus molecular data, both classes of data are themselves conflicting. We contend that much of the discrepancy among these studies is due to improper choice of out-group, limited taxonomic sampling, or both. We examined approximately 3 kb of mitochondrial DNA from 104 bats representing the taxonomic, geographic, and morphologic diversity within all families (except the monotypic Craseonycteridae) and 58 additional taxa representing 12 other orders of mammals. Results of our analyses strongly support other recent work indicating that Archonta is not a natural assemblage and that the sister taxon to Chiroptera may include Cetartiodactyla, Perissodactyla, Carnivora, and possibly Pholidota. Using representatives of these taxa as out-groups to evaluate interfamilial relationships within Chiroptera, we detected strong support for recognition of the suborders Yinpterochiroptera and Yangochiroptera. Within Yangochiroptera, our analyses strongly support expansion of the superfamily Noctilionoidea to include the New World Thyropteridae and Furipteridae.

The long-tailed shrew (Sorex dispar) occurs at upper elevations on wooded slopes in the Appalachian Mountains from North Carolina to Quebec. Size in long-tailed shrews is clinal, decreasing from south to north. A closely related species is the slightly smaller Gaspé shrew (Sorex gaspensis), known primarily from the Appalachians farther north in the Gaspé Peninsula of Quebec. Long-tailed shrews captured in northern Maine appear to fit within the size range of the Gaspé shrew which brings up the question: are these specimens small bodied long-tailed shrews at the northern end of their range, Gaspé shrews at the southern edge of their range, or are the 2 species part of the same continuous distribution and, in fact, conspecific? A morphological comparison with other studies indicates that a continuous cline cannot be ruled out. Phylogenetic analysis of mitochondrial DNA d-loop sequences showed that S. gaspensis and S. dispar cluster with no taxonomic or geographic structure, suggesting that they are conspecific.

Genetic variation at 6 nuclear microsatellite loci with biparental inheritance and the maternally inherited mitochondrial DNA (mtDNA) was studied at 3 geographic scales (rookeries, regions, and stocks) in Steller sea lions (Eumetopias jubatus). Genetic variation was high in both nuclear and mtDNA markers as revealed by a near range-wide survey of 21 rookeries. However, population structure was not well defined, and there was no obvious phylogeographic pattern to the distribution of microsatellite alleles. This contrasts with a clear phylogeographic pattern revealed by control-region sequences of mtDNA in which 2 well-differentiated stocks, eastern and western, are defined as well as 2 distinct groups, Asian and central, in the western stock. Effective migration estimates are consistently higher for the nuclear loci than for mtDNA. The difference in patterns between the biparentally and maternally inherited genetic markers can be explained by relatively high male dispersal rates and female philopatry, or else there has been insufficient time since populations have been isolated for the nuclear loci to have diverged. It is recommended that the presently accepted stock structure be retained for management purposes and that further studies be carried out to test the male dispersal hypothesis.

The taxonomic status of the 2 morphologically distinct forms of Dall's porpoises, Phocoenoides dalli (dalli- and truei-type) remains unresolved. To address this uncertainty, mitochondrial DNA (mtDNA) sequences were used to estimate phylogenetic relationships between the 2 types and, in conjunction with microsatellite markers, to test genetic differentiation between truei- and dalli-type populations. Twenty-three truei-type and 113 dalli-type specimens were sequenced for 379 base pairs of the mtDNA control region and genotyped for 6 microsatellite loci. Twelve haplotypes were shared between truei- and dalli-types. A neighbor-joining tree of mtDNA haplotypes showed 2 distinctive clades, each containing individuals from both types. This suggests that truei- and dalli-types are forms of the same species. However, at the population level, statistically significant genetic differentiation was found between truei-type and sympatric dalli-type populations. These results argue that differentiation between truei- and dalli-types is at the population level, much in the same way that dalli-type populations differ among each other.

Incomplete observations of matings and uncertainty about which male's sperm is responsible for fertilization have traditionally made paternity difficult to document in field research. Modern genetic methods, combined with field data, now facilitate assigning paternity in many species. I investigated male reproductive success in white-tailed deer (Odocoileus virginanus) by a microsatellite paternity analysis, which revealed that males from all age classes >0.5 years fathered offspring. The oldest males did not monopolize matings; for 12 of 14 males ≥3 years old who fathered young, the numbers of females mated and young fathered were highly variable (1–7 and 1–9, respectively). Three yearling males that bred mated with 3 yearling females and one 2.5-year-old female, whereas all other male age classes mated with females from any age class. In addition, the 1st cases of frequent multiple paternity in free-ranging white-tailed deer were documented. Multiple paternity was found in 22% of twins, with paternity assigned at the 95% confidence level. Males that jointly sired twins appeared at least a year apart in age (maximum age difference, 3 years). It is proposed that older males displaced younger males tending estrous females.