The ontogeny of skull allometry has been the subject of research in didelphid, microbiotheriid, and dasyurid marsupials. We described and compared postweaning stages of cranial development in the woolly opossum Caluromys philander, a member of a distinct lineage of didelphids. We identified 31 qualitative morphological changes between juveniles and adults, many related to the trophic apparatus. Early development of the paracanine fossa in the snout, correlated with the presence of well-developed canines in juveniles, represents a remarkable difference between the ontogeny of C. philander and other marsupials. We performed bivariate and multivariate analyses of allometry on a data set composed of 14 cranial measurements and 45 specimens. Allometric scaling showed that braincase is relatively small in adulthood, whereas other neurocranial components, particularly the orbit, grew isometrically along its length. The palate becomes elongated by the combination of the isometry of its length and the negative allometry of its width. The rostrum lengthened, but its height remained proportionally constant. In relative terms the temporal fossa expanded inward following the marsupial model that combines the negative allometry of the braincase and the isometry of the zygomatic breadth. The mandible increased in robustness. The skull ontogeny of C. philander shares 4 allometric trends with 2 didelphids (Didelphis albiventris and Lutreolina crassicaudata) and two australidelphians (Dromiciops gliroides and Dasyurus albopunctatus). Three of these trends, breadth of palate, breadth of braincase, and height of occipital plate, were allometrically negative, whereas height of the dentary was positive. These common allometric trends may be interpreted as symplesiomorphic for marsupials, suggesting a high degree of conservatism in the skull development of Caluromys and other marsupials.

Understanding how environmental change influences the behavior of organisms is central for both ecological understanding and species conservation. We used camera traps to monitor the diurnal variation in activity of 3 ubiquitous terrestrial mammals in neotropical forests—nine-banded armadillos (Dasypus novemcinctus), common opossums (Didelphis marsupialis), and red-rumped agoutis (Dasyprocta leporina)—across a fragmented forest landscape of the southern Brazilian Amazon. Results from a total of 3,086 camera-trap days distributed across 21 forest patches (ranging in size from 2 to 14,480 ha) and 2 undisturbed continuous forest areas were used to test the effects of a series of abiotic and forest disturbance variables on species activity. An information theoretic analysis revealed significant predictors of the temporal distribution of activity that varied among species. Habitat fragmentation affected the activity of both nocturnal species, but effects of habitat patch area depended on interactions with disturbance variables for the common opossum. Of the 3 species investigated, D. novemcinctus exhibited the greatest variation in activity in relation to forest patch size. Armadillos were strictly nocturnal in forest areas >1,000 ha, whereas their foraging activity switched to a cathemeral pattern, with up to 60% of all photos recorded during the day in smaller forest patches (<1,000 ha). In contrast, the time since forest patches had been isolated was the only significant predictor of activity patterns for agoutis, a diurnal species exhibiting a bimodal activity pattern. Our results support the hypothesis that behavioral plasticity is an important determinant of species persistence in small forest remnants dominated by edge effects.

The relative importance of factors that influence the habitats that animals select often varies with spatial scale. We evaluated the hypotheses that habitat selection by 2 sympatric slender opossums (Marmosops) is scale-dependent, and that coexistence in the gray slender opossum (Marmosops incanus) and the Brazilian slender opossum (M. paulensis) is enabled through differential use of habitat components or segregation in the use of vertical strata, or both. At a mesohabitat scale both species selected areas with dense understory, especially vertical obstruction 0–0.5 m above the ground. At a finer, microhabitat scale M. incanus preferred places with higher plant cover and vertical obstruction 0.5–1.0 m above the ground, and M. paulensis showed no evident pattern of selection. This result supports the hypothesis that habitat selection is scale-dependent. Although both species selected similar habitats at the mesoscale, we found segregation in the use of vertical strata, with M. paulensis being more terrestrial than M. incanus. Habitat segregation could reflect the intrinsic habitat preferences of each species or potential competition for space between the 2 congeners.

The broad-clawed shrews (Soricomorpha: Soricidae: Cryptotis) encompass a clade of 5 species—Cryptotis alticolus (Merriam), C. goldmani (Merriam), C. goodwini Jackson, C. griseoventris Jackson, and C. peregrinus (Merriam)—that is known collectively as the Cryptotis goldmani group and is characterized by broadened forefeet, elongated and broadened fore claws, and broadened humeri. These shrews are distributed in highland regions from central Mexico to Honduras. Two broad-clawed shrews, C. goodwini and C. griseoventris, occur in southern Mexico and Guatemala and are presumed sister species whose primary distinguishing feature is the larger size of C. goodwini. In an investigation of variation within and between these 2 species, I studied characteristics of the postcranial skeleton. Statistical analyses of a variety of character suites indicate that the forelimb morphology in this group exhibits less intraspecific variation and greater interspecific variation than cranio-mandibular morphology, although most skull characters support groupings based on forelimb characters. Together, these characters define 4 distinct groups among the specimens examined. C. griseoventris is restricted to the northern highlands of Chiapas, Mexico, and C. goodwini occurs in the southern highlands of Chiapas and Guatemala. Herein, I describe 2 new species of broad-clawed shrews from the Sierra de los Cuchumatanes, Guatemala.

We examined seasonal variation in urine concentration and fecal water content (FWC) of free-ranging bats inhabiting the tropical deciduous forest of the Chamela-Cuixmala Biosphere Reserve, Mexico, which is characterized by marked dry and rainy seasons. We tested the hypothesis that bats inhabiting this forest would exhibit seasonal physiological changes to maintain water balance. We predicted that bats would have higher urine concentrations and reduced FWC during the dry season. Our results were consistent with the 1st prediction for the insectivore, Parnell's mustached bat (Pteronotus parnellii), but not for the Jamaican fruit bat (Artibeus jamaicensis). Our data were consistent with our 2nd prediction for P. parnellii and the facultative nectarivore Pallas' long-tongued bat (Glossophaga soricina), but not for A. jamaicensis. Our findings indicate that for the bats we studied, the 2 routes by which water is lost were affected differently by seasonal changes in water availability as a function of feeding habits.

I summarized data on eastern red bats (Lasiurus borealis), hoary bats (Lasiurus cinereus), and silver-haired bats (Lasionycteris noctivagans) that were obtained by mistnetting in the Lower Peninsula of Michigan over a 32-year span (1978–2009) to test published predictions, partly or wholly based on museum specimens, that adult sex ratios in summer are female-biased. Males were more common in the netting sample than females among silver-haired bats (88%; n  =  57) and eastern red bats (70%; n  =  458), whereas male and female hoary bats (n  =  40) were equally abundant. Silver-haired bats and male hoary bats were more common north of a line separating the Deciduous Forest Biome and a transition to the Coniferous Forest Biome. The presence of male-dominated populations of all species at low-elevation sites in northern Lower Michigan suggested that distribution of the sexes in each species is more complex than previously thought. The sex ratio of adult eastern red bats was more skewed in July (74% male) than in June (58%), which might indicate late northward migration by males.

We examined patterns of genetic variation in Rousettus madagascariensis from Madagascar and R. obliviosus from the Comoros (Grande Comore, Anjouan, and Mohéli). Genetic distances among individuals on the basis of 1,130 base pairs of the mitochondrial cytochrome b (Cytb) locus were estimated from specimens collected from 17 sites on Madagascar, 3 sites on Grande Comore, 3 sites on Anjouan, and 2 sites on Mohéli. We observed little variation in Madagascar and nearshore island samples (maximum 1.1%) and interisland Comoros samples (maximum 1.8%). In contrast, pairwise distances between different sampled sites on Madagascar and the Comoros varied from 8.5% to 13.2%. For 131 Malagasy animals, 69 unique haplotypes were recovered with 86 variable sites, and for 44 Comorian individuals, 17 unique haplotypes were found with 30 variable sites. No haplotype was shared between Madagascar and the Comoros, adding to previous morphological evidence that these 2 populations should be considered separate species. Cytb data showed that Rousettus populations of Madagascar (including nearshore islands) and the Comoros are respectively monophyletic and display no geographic structure in haplotype diversity, and that R. madagascariensis and R. obliviosus are strongly supported as sister to each other relative to other Rousettus species. Genotypic data from 6 microsatellite loci confirm lack of geographic structure in either of the 2 species. In pairwise tests of population differentiation, the only significant values were between samples from the Comoro Islands and Madagascar (including nearshore islands). Estimates of current and historical demographic parameters support population expansion in both the Comoros and Madagascar. These data suggest a more recent and rapid demographic expansion in Madagascar in comparison with greater population stability on the Comoros. On the basis of available evidence, open-water crossings approaching 300 km seem rarely traversed by Rousettus, and, if successful, can result in genetic isolation and subsequent differentiation.

Natural disturbance is a key determinant of ecosystem structure and function. Disturbances can create novel resource patches and modify habitat structure, thereby inducing spatial heterogeneity in the trade-off between food acquisition and predator avoidance by prey. We evaluated how canopy gap dynamics in eastern Canadian old-growth boreal forest alter the spatial distribution of food and cover for snowshoe hares (Lepus americanus) and how hares responded to these spatial patterns. We 1st compared browse availability within canopy gaps and the surrounding forest. We then examined fine-scale habitat selection, movement patterns, and foraging decisions by hares during winter. Perception of risk within canopy gaps was assessed using foraging experiments. We found that browse availability was 4 times higher within gaps than under forest cover. Although hares acquired most of their browse from gaps, their use of space during winter was influenced by a greater perception of predation risk within gaps. Hares selectively used areas of higher canopy closure suggesting that they restricted their use of gaps to foraging activities. Furthermore, hares biased their movements away from gaps or increased their speed of travel in areas of relatively low cover. Hares consumed experimental browse stems more intensively under forest cover than in canopy gaps, indicating a trade-off between food and safety. When foraging within canopy gaps, hares also were less likely to use both experimental and natural food patches located far away from cover. Our study demonstrates how gap dynamics in old-growth stands can structure the fine-scale spatial organization of a key prey species of the boreal forest by creating spatial heterogeneity in their landscapes of fear and food. Spatial variation in browse use in response to predation risk may in turn influence patterns of sapling growth and survival within canopy gaps. Gap dynamics therefore may be a fundamental process structuring predator–prey interactions in old-growth boreal forests.

Although individuality in alarm calls has been reported for many ground-dwelling sciurids, the degree to which the vocal identity encoded in alarm calls is stable with time has been studied only for a single sciurid species. Thus, no comparable data are available. We examined the retention of the vocal keys to individual identity after hibernation in a natural colony of yellow ground squirrels (Spermophilus fulvus), long-lived, obligate-hibernating rodents that maintain stable social groups for years. We recorded alarm calls in 2 subsequent years, separated by hibernation, from 22 individually marked animals. All individuals could be distinguished with high probability by their alarm calls within a year. However, only 6 of the 22 animals kept their alarm calls stable after hibernation. Sex, age, year of data collection, and the distance that individuals moved between years did not have significant effects on the retention of a stable alarm call structure after hibernation. Given the low proportion of individuals with stable alarm calls, vocal identity cannot be the only modality sufficient to secure the recovery of personalized social relationships after hibernation in the yellow ground squirrel.

Using genetic analyses, researchers have reported multiple paternity in many mammals, including ground-dwelling sciurids. Within the marmots, however, genetic mating systems have been described for relatively few species, and multiple paternity has been documented only in alpine marmots (Marmota marmota), a highly social, cooperative breeder. We used microsatellite markers to examine paternity and to describe the mating system of woodchucks (M. monax), whose social organization lies at the opposite end of the continuum from alpine marmots. We could assign paternity to 55% of juveniles. Multiple paternity occurred in 63% of litters, with up to 4 males siring offspring within a litter. Mates generally were not closely related, although relatedness calculations suggested that some pairs included close kin. Females and their mates typically lived near each other and shared portions of their home ranges. Overall, woodchucks in this natural population could be classified as genetically promiscuous. Both males and females can benefit from acquiring additional mates; however, the benefits of multiple female mating deserve further study.

Natural nests of the European ground squirrel (Spermophilus citellus) are constructed almost exclusively of fresh fescue (Festuca pseudovina: Poaceae). We performed laboratory experiments to understand the functional significance of preference of wild squirrels for nest material. We examined the factors contributing to nest quality by monitoring the construction and analyzing the composition of squirrel nests. As in the wild, squirrels showed strong preference for fescue during the laboratory tests and preferred fresh material to dry material. Because preference for fresh material was not expected, because high water content reduces insulation, we manipulated the moisture content of nests made from either fresh or dry fescue to determine how nest quality and moisture level contribute to insulation. We found that the insulation property of fresh grass nests was superior to nests constructed from dry grass only. Intracellular water in the nest material did not affect thermal conductance and insulation significantly. We concluded that fresh fescue provided a more flexible material that allows squirrels to construct nests with better insulation under both field and laboratory conditions.

Understanding the effects of forest fragmentation on tree-dwelling sciurids is of particular interest given their arboreal habits and the extent of anthropogenic habitat fragmentation inflicted upon North American forest ecosystems over the past 2 centuries. In this study we investigate occurrences of northern flying squirrels (Glaucomys sabrinus) and red squirrels (Tamiasciurus hudsonicus) in forest fragments in southern Ontario, Canada, as a function of local habitat and landscape features. During the summer of 2006 we measured occurrence via livetrapping in 24 forest fragments ranging in size from 4 to 2,881 ha, each adjacent to or surrounded by active row-crop agriculture. In addition to patch area and measurements of local habitat features, we calculated 4 landscape metrics in variously sized circular landscape windows: number of patches, forest cover, mean proximity index, and distance to the nearest neighboring patches. Occurrence of G. sabrinus was positively correlated with patch area (P  =  0.016) but not with other features, whereas occurrence of T. hudsonicus was positively associated with basal area of coniferous trees (P  =  0.047) but not with other habitat or landscape features. Populations of T. hudsonicus did not show fragmentation effects, likely due to high vagility and high population growth potential. Northern flying squirrels were not found in patches < 29 ha in size and, as estimated from a receiver operating characteristic curve, the ideal minimum fragment size for patch occupancy was 48.25 ha. Our data support conclusions that diverse management schemes may be required to preserve relatively large contiguous tracts of forest for G. sabrinus and appropriate conifer structure for T. hudsonicus in a way that will facilitate the persistence of these 2 species in deciduous Great Lakes–St. Lawrence forest ecosystems.

Populations of flying squirrels from the Mesoamerican highlands represent the least understood members of the genus Glaucomys. Traditionally, these populations have been considered to be southern disjuncts of the southern flying squirrel (G. volans), a species that is widespread across the deciduous and mixed-deciduous forests of eastern North America. The limited number of museum specimens of Mesoamerican flying squirrels has made discerning the systematic and biogeographic relationships of these populations a challenge. We used ancient DNA techniques to extract, amplify, and sequence a 571-base pair segment of the mitochondrial DNA cytochrome-b gene from 22 of 34 available museum specimens. Mesoamerican flying squirrel data were combined with homologous sequences from representative populations of Glaucomys from the United States and Canada. This combined data set was analyzed using maximum-likelihood and Bayesian methods. Results indicate that G. volans is monophyletic and contains 2 monophyletic subclades, 1 from Mesoamerica and the other from eastern North America. Our results have important implications regarding the nature of the historical biogeographic connection between the temperate biotas of Mesoamerica and eastern North America. The divergence of populations of G. volans in eastern North America from those in Mesoamerica appears to have occurred in the middle Pleistocene (approximately 0.75–0.5 × 10⁶ years ago), considerably earlier than a late-Pleistocene connection previously hypothesized. Our analyses also show that populations of G. volans from eastern North America exhibit a clear signature of recent, rapid population expansion and that Mesoamerican populations of G. volans exhibit higher levels of genetic variability than those found across eastern North America. The documentation of substantial genetic diversity and population structure in Mesoamerican populations of G. volans is especially noteworthy because these populations face ongoing habitat loss due to human activities. Anthropogenic habitat degradation of the high-elevation forests these mammals inhabit likely will be exacerbated by global climate change. Therefore, we suggest that the conservation status of Mesoamerican flying squirrels be considered data deficient at a minimum with a high potential for future studies to reveal that many populations are near threatened or vulnerable.

Movement patterns of Calomys musculinus in linear habitats were studied in relation to sex, season, year, abundance, and width of border. Movement distances (MDs) were measured by seasonal capture, mark, and recapture samples during 2 years in wide and narrow borders in agroecosystems. The smallest MDs were registered in autumn and the highest in spring. In the breeding period MDs of males were larger than those of females. In the nonbreeding period MDs were similar between sexes. Effects of sex on MD were consistent with the promiscuous mating system of C. musculinus. MDs were greater in narrow than in wide borders. The narrowness of suitable habitats would force the mice to extend foraging trips in narrow borders. Opportunistic behavior of C. musculinus allows it to use linear habitats in a similar way to the 2-dimensional natural habitats.

Przewalski's gazelle (Procapra przewalskii) and the Tibetan gazelle (P. picticaudata) are endemic, closely related, and endangered ungulates of the Qinghai-Tibetan Plateau. The 2 species often occur in mixed-species groups in the upper Buha River of the Plateau. We studied the composition and size of their mixed-species groups over 2 years to determine whether such groups aggregate by chance and to determine a posteriori potential costs and benefits associated with the formation of mixed-species groups. Sex composition and size distribution were similar in single-species groups for both species. Given that population density also was similar for these species, we expected that mixed-species groups that formed by chance would consist of an equal mix of the 2 species. This was true in male and in mixed-sex groups; however, the proportion of female groups composed of Przewalski's gazelles was much larger than expected. In addition, mixed-species groups in winter never included males of both species. The results suggest that these 2 gazelle species do not associate randomly. Mixed-species groups were larger than single-species all-female, all-male, and mixed-sex groups, suggesting that individuals in larger groups may benefit from a reduction in predation risk. The occurrence of mixed-sex, mixed-species groups may increase the risk of crossbreeding and represent a cost to the formation of mixed-species groups in these two gazelle species.

Spatial genetic structure in white-tailed deer (Odocoileus virginianus) has been examined at regional scales, but genetic markers with the resolution to detect fine-scale patterns have appeared only recently. We used a panel of microsatellite DNA markers, radiotelemetry data, and visual observations of marked deer to study fine-scale social and genetic structure in a high-density population of white-tailed deer (12–20 deer/km²). We collected genetic data on 229 adult females, 102 of which were assigned to 28 social groups. Our results were consistent with the conceptual model of white-tailed deer social structure, where philopatric females form social groups composed of related individuals. Within-group relatedness values approached the expected value for 1st cousins (R  =  0.103, SE  =  0.033), but individuals among groups (R  =  −0.014, SE  =  0.003) and overall (R  =  −0.009, SE  =  0.003) were unrelated. Fixation indices revealed a significant departure from equilibrium values among social groups (F_ST  =  0.076, SE  =  0.007) and an excess of heterozygotes within groups (F_IS  =  −0.050, SE  =  0.018), consistent with theoretical expectations for mammal populations characterized by female philopatry and a polygynous mating system. Analyses of spatial autocorrelation indicated genetic structuring occurred at a very fine spatial scale, where pairs of adult females within 1 km were genetically nonindependent. The occurrence of fine-scale genetic and social structure has implications for the ecology and management of white-tailed deer, including habitat use and resource competition, offspring sex allocation theories, disease transmission, and the consideration of social behaviors in management.

Conservation of huemul (Hippocamelus bisulcus), an endangered South American deer, is hindered by a lack of quantitative information on its population dynamics. We conducted a 3-year study in Chilean Patagonia to assess the dynamics of huemul by monitoring known individuals. We fitted 55 deer of all sex–age classes with either radiocollars, radio ear tags, or conventional ear tags, and identified 33 additional deer through natural marks. Kaplan–Meier estimates revealed that annual survival of adult females was high and stable (0.94 ± 0.07 SD), but survival of female fawns was low and variable (0.13 ± 0.18). Predation was the predominant cause of mortality for deer of all age classes. Fertility rates were lower (0.72 ± 0.20) than in other cervids of similar size. Simulations of the finite rate of increase (λ) suggest that the population is currently stable. Sensitivity analysis showed that any decrease in adult female survival would have drastic effects on λ. Consequently, management should maintain high adult survival and improve recruitment. Continued monitoring of individuals is required to provide baseline data for comparison with other populations and to inform recovery strategies of small and fragmented populations.

During his expeditions to the North Pole Robert Peary harvested at least 233 Peary caribou (Rangifer tarandus pearyi) from the northeast (NE) portion of Ellesmere Island, Nunavut, Canada. To assess the impact of this intensive local harvest we compared historic and contemporary samples. We explored 2 models of repopulation for this region. In the recovery model animals not hunted by Peary were the source of the current population. In the recolonization model animals from adjacent regions contributed to the current population. A genetic assessment of mitochondrial DNA (mtDNA) diversity comparing historic specimens (n  =  12) to contemporary samples from the same region (n  =  22) indicates the loss of 1 major mtDNA haplogroup. In this region historic and contemporary samples were significantly differentiated from one another. Combined mtDNA (n  =  121) and 9 nuclear DNA loci (n  =  151) indicate that the contemporary NE animals are most similar to those in adjacent regions to the south. We interpret this as supporting our recolonization model and suggest that, following Peary, animals dispersed north from central Ellesmere. Animals from the region to the west (NW) of NE showed the greatest differentiation from all other regions, suggesting that although proximate in distance, movement between the NW and NE might always have been limited. The NW region was unique in that it contained 1 predominant mtDNA haplotype at high frequency (0.88), the lowest observed heterozygosity (H_O  =  0.50), and the highest mean relatedness (R  =  0.063). Our combined results highlight the sensitivity of populations at the range limit to stochastic events and the potential limits to recovery following significant perturbations.

Mitigation of predation risk promotes high-elevation dispersion prior to birthing in many ungulate populations. Coyotes (Canis latrans) account for nearly 80% of pronghorn (Antilocapra americana) fawn mortality in Yellowstone National Park, but reintroduced gray wolves (Canis lupus) and factors associated with mountainous terrain can strongly influence space use by predators during summer and are likely to underlie significant spatial variation in survival rates of pronghorn fawns. We used generalized logit models paneled by maternal identity to assess the relative and interactive influences of summer wolf density, winter snow depth, and terrain slope on survival of pronghorn fawns in Yellowstone during 1999–2001 and 2004–2006. In this partially migratory population only migrant pronghorn accessed areas where wolves were numerous and winter snow depths were high. Survival of migrant fawns was higher in areas that experienced deep winter snow and had steeper slope. The influence of wolves on fawn survival was positive only in areas of low winter snowfall where coyotes were abundant, supporting predictions of a coyote-mediated effect of wolves and winter snowfall on pronghorn reproductive success. Our results suggest that deep winter snow, coupled with constraints on mobility imposed by reproduction in populations of social carnivores, can lead to the formation of high-elevation refugia for migrant ungulates. This research offers novel insights into the indirect effects of wolf restoration and climatic factors on the Yellowstone predator–prey complex and a conceptual framework for examining the ecological effects in other mountain communities of restoration of, and seasonal space use by, large carnivores.

Jaguars (Panthera onca) often prey on livestock, resulting in conflicts with humans. To date, kill rates and predation patterns by jaguars have not been well documented. We studied the foraging ecology of jaguars in an area with both livestock and native prey and documented kill rates, characteristics of prey killed, patterns of predation, and the influence of prey size on the duration at kill sites and the time interval between kills. Between October 2001 and April 2004 we monitored 10 jaguars equipped with global positioning system (GPS) collars. We collected 11,787 GPS locations and identified 1,105 clusters of locations as sites of concentrated use (e.g., kill sites, bed sites, and dens). Of these, we found prey remains at 415 kill sites and documented 438 prey items. Kills were composed of 31.7% cattle (9.8% adults and 21.9% calves), 24.4% caiman (Caiman crocodilus yacare), 21.0% peccaries (mostly Tayassu pecari), 4.1% feral hogs (Sus scrofa), 3.9% marsh deer (Blastocerus dichotomus), 3.2% giant anteaters (Myrmecophaga tridactyla), 2.0% capybaras (Hydrochoeris hydrochaeris), 1.6% brocket deer (Mazama americana and M. gouazoubira), and other avian, mammalian, and reptilian species. Individual jaguars differed in the proportion of each species they killed and the proportion of native prey versus cattle. Although all 10 cats killed cattle, 5 killed a high proportion of cattle (>35% of kills), and 3 killed few cattle (<15%). Males (27%) and females (35%) killed cattle in similar proportions. In contrast, male jaguars killed a higher proportion of peccaries than did females, and female jaguars killed more caiman than did males. The mean kill rate for all jaguars was 4.3 days ± 4.4 SD between known consecutive kills. The time interval to the next subsequent kill by jaguars increased with increasing prey size. Jaguars also increased the length of time at a carcass as prey size increased. Jaguar kill rates on peccaries steadily increased over the 4-year study. In contrast, kill rates on cattle decreased during the same period. Rainfall, and subsequent water levels on the Pantanal, was the main driver of seasonal kill rates by jaguars on cattle and caiman. As water levels increased, predation on caiman increased as caiman became more distributed throughout the landscape. Conversely, as water levels fell, caiman became less plentiful, and cattle were moved out into pastures thereby increasing their availability to more jaguars.

Spacing patterns of large carnivores can affect demographic parameters of populations that, in turn, influence effective population size. As a result, better understanding of spatial structure can provide insight into effective conservation strategies. We examined home-range size, spacing characteristics, and changes in land tenure of radiocollared Amur tigers (Panthera tigris altaica) on the Sikhote-Alin Biosphere Zapovednik, Russia, from 1992 to 2006. We predicted that both sexes would maintain spatially exclusive home ranges and that subadult female tigers would tend toward philopatry and males would disperse. Home ranges (95% fixed kernel estimates; mean ± SD) of resident females (n  =  20 home ranges of 14 females; 390 ± 136 km²) were significantly (P  =  0.003) smaller than those of males (n  =  6 home ranges of 5 males; 1,385 ± 539 km²). Geometric mean overlap between adjacent females (0.11 ± 0.11 SD) did not differ from that between adjacent males (0.14 ± 0.12). All radiocollared male cubs dispersed (n  =  7), but only 2 of 6 female cubs dispersed from their natal home ranges. When human-caused mortality was low, female tigers survived long enough to divide their home range with their daughters, resulting in smaller home ranges and a higher density of breeding females. All females reproduced in these smaller territories, suggesting that they maintained home ranges that were larger than needed to meet reproductive demands. However, when human-caused mortality was high, females often did not survive long enough to bequeath home ranges to daughters, and population density was apparently maintained well below carrying capacity. The impacts of poaching appear to extend beyond the direct loss of individuals, and therefore reserves must be well protected if they are to serve as source populations for adjacent, unprotected areas of tiger habitat.

Spatial dynamics and frequency of interaction between mating individuals are difficult to observe in the wild, and linking behavioral and genetic mating systems is particularly challenging for nocturnal or otherwise cryptic mammals. We monitored 29 (11 male and 18 female) adult raccoons in northeastern Illinois to gain a better understanding of how individuals interacted with one another during the mating season (December–March) of 2005. Adults were monitored with proximity-detecting radiocollars to determine the amount of spatial overlap and rate of contact among members of the local population, including those parent pairs that had mated successfully. We identified successful matings by conducting parentage analyses on 43 juveniles using 15 highly variable microsatellite loci. We were unable to identify parents for 25 of 43 juveniles, which greatly reduced our ability to assess the raccoon mating system. However, we present novel data on contact rates and den-sharing incidents between known parental pairs. We found that 3 of 4 parent pairs shared >35% of their daytime resting areas and >26% of their core resting areas. Contact rates of parent pairs varied, ranging from 0.1 to 0.9 contacts/day. Parent pairs were not observed to share dens during the mating season. However, among the remainder of the adult population, we found a sharp increase in instances of den sharing between unrelated adults that coincided with the peak of the mating season. Finally, male coalitions were not successful at sequestering breeding access to reproductive females; only 38.8% of juveniles were sired by males known to live in groups.

The estimation of life-history parameters for a threatened species is important for understanding its biology and helping to determine management options. This research investigates age- and sex-related survival estimates incorporating tag loss for New Zealand (NZ) sea lions (Phocarctos hookeri) from Sandy Bay, Enderby Island, Auckland Islands, New Zealand, using multistate mark–recapture data from known-age individuals over 8 years (1997–1998 to 2005–2006). Survival estimates and tag loss rates differed significantly by sex and age class, with adult males having the lowest tag retention of any age or sex class and females ≥ 3 years old having lower survival estimates than their male counterparts. The variability and lower female survival relative to males is a critical problem for NZ sea lions, because even small changes in adult female survival significantly affect population trends for such large, long-lived mammals.