The unprecedented rate of urbanization over the past several decades is a major concern for conservation globally and has given rise to the multidisciplinary field of urban ecology. This field explores the direct and indirect effects of human activities on food-web dynamics, community structure, and animal behavior in highly modified urban ecosystems. Urban ecosystems are typically characterized by reduced species diversity but increased abundance of a few species able to exploit anthropogenic food sources. For many urban mammalian and avian species direct resource subsidization is difficult to assess using traditional means such as scat analysis. Here we show how stable isotope analysis can be used to assess the exploitation of anthropogenic foods in an endangered carnivore, the San Joaquin kit fox (Vulpes macrotis mutica) inhabiting the southern San Joaquin Valley in California. Examination of carbon (δ¹³C) and nitrogen (δ¹⁵N) isotope data shows that kit foxes living in urban Bakersfield, California, extensively exploit anthropogenic foods, which sharply contrasts with dietary data derived from scat analysis. Urban kit foxes had significantly higher δ¹³C and lower δ¹⁵N values than foxes from adjacent nonurban areas and had similar isotope values as Bakersfield human residents, which suggests a shared food source. In contrast, examination of isotopic data for nonurban kit foxes shows that they largely consume the most abundant natural prey species found in their scats. Stable isotope analysis offers a rapid and cost-effective means of evaluating the degree to which urban wildlife populations exploit anthropogenic foods in areas where native C₄ vegetation is relatively uncommon or absent, important in assessing the direct impacts of human activities on food-web dynamics in urban ecosystems. We anticipate that the isotopic gradients used here will be useful in assessing the exploitation of anthropogenic foods in other urban wildlife populations.

Urban development can have multiple effects on mammalian carnivore communities. We conducted a meta-analysis of 7,929 photographs from 217 localities in 11 camera-trap studies across coastal southern California to describe habitat use and determine the effects of urban proximity (distance to urban edge) and intensity (percentage of area urbanized) on carnivore occurrence and species richness in natural habitats close to the urban boundary. Coyotes (Canis latrans) and bobcats (Lynx rufus) were distributed widely across the region. Domestic dogs (Canis lupus familiaris), striped skunks (Mephitis mephitis), raccoons (Procyon lotor), gray foxes (Urocyon cinereoargenteus), mountain lions (Puma concolor), and Virginia opossums (Didelphis virginiana) were detected less frequently, and long-tailed weasels (Mustela frenata), American badgers (Taxidea taxus), western spotted skunks (Spilogale gracilis), and domestic cats (Felis catus) were detected rarely. Habitat use generally reflected availability for most species. Coyote and raccoon occurrence increased with both proximity to and intensity of urbanization, whereas bobcat, gray fox, and mountain lion occurrence decreased with urban proximity and intensity. Domestic dogs and Virginia opossums exhibited positive and weak negative relationships, respectively, with urban intensity but were unaffected by urban proximity. Striped skunk occurrence increased with urban proximity but decreased with urban intensity. Native species richness was negatively associated with urban intensity but not urban proximity, probably because of the stronger negative response of individual species to urban intensity.

Habitat fragmentation is a major cause of population reduction and loss, and increasing evidence suggests that effects of fragmentation on populations vary as a function of the life history and autecology of species. We investigated the effect of anthropogenic habitat fragmentation on several indicators of population health in the agile antechinus (Antechinus agilis), a small Australian marsupial with an unusual life history. We examined relative abundance, body condition (mass–size residuals [MSR]), and ectoparasite load. Abundance was 2.3-fold higher in continuous than in fragmented Eucalyptus forest, and ectoparasite loads were higher in fragmented than in continuous forest in March, April, May, and July, but not in June or August. Unexpectedly, MSR also was higher in what would usually be considered the less-favorable fragmented habitat than in continuous forest (means: fragmented: 0.6 g; continuous: −0.9 g). Other body-condition indicators did not differ consistently between fragmented and continuous forest populations. Results suggest that an apparently common and secure small mammal species could be declining in anthropogenically fragmented and degraded habitat. Although habitat fragmentation has been associated with nutritional stress in vertebrates, food availability probably was not contributing to the lower abundance of agile antechinus in habitat fragments. The findings indicate that care is needed when generalized expectations about the response of a species to anthropogenic habitat fragmentation are used to inform conservation management.

Rapidly increasing urbanization creates novel environmental conditions for mammals even in already human-dominated, agricultural landscapes. Previous research on the behavioral responses of mammals to urbanization has focused on carnivores. Herbivores may respond to similar factors as carnivores, but herbivores also could respond to landscape alterations that generate variation in predation risk. We examined movements of 35 radiomarked, adult woodchucks (Marmota monax) located across an urbanization gradient within an agricultural landscape in central Illinois from 2007 to 2008. As predicted, home-range size was related negatively to urbanization. Home-range size of woodchucks in urban areas was ∼10% of that of rural woodchucks. Urbanization had stronger effects on home-range sizes of males compared to females. Woodchucks are multiple central-place foragers, and their use of burrows within home ranges also was influenced by urbanization, with number of burrows per individual decreasing with urbanization. Because number of burrows was not scaled proportionally to home-range size, however, distances between burrows decreased in urban areas, and predation risk during interburrow movements should be reduced for urban woodchucks. Our results demonstrate the ability of woodchucks to exhibit substantial behavioral plasticity in response to urbanization and provide insights into how space use by multiple central-place foragers relates to predation risk.

Ecologists often rely on unique natural markings to identify individual free-ranging animals without disturbing them. We developed a computer-aided photo-identification system for identifying polar bears (Ursus maritimus) based on whisker spot pattern recognition. We automated our system so that the selection of 3 reference points on the input image is the only manual step required during image preprocessing. Our pattern-matching algorithm is unique in that the variability within spot patterns is considered fully rather than representing them as points and applying a point-pattern matching algorithm. We also measured the reliability of our method as probabilities of true positives and false positives using photographs of various qualities taken at different angles. When we excluded photographs of poor quality and angle the probability of true positives was >80% at a false positive probability of 10%. A new photograph could be preprocessed in <1 min and tested against a reference library of 100 individuals in <10 min. Our computer-aided identification system could be extended for use in other species with variable spot patterns, which could be useful in efforts to estimate various population dynamics parameters essential for the study and conservation of wildlife, particularly threatened and endangered species.

Radiotelemetry is used to quantify behavioral, ecological, and physiological variables of animals. Because of technological limitations, relative transmitter size generally increases with decreasing body mass of the study animal, and the recommended transmitter mass of <5% of body mass often prohibits work on small mammals. We compared burst running speed, important for predator avoidance, in 2 small marsupials, Sminthopsis crassicaudata (fat-tailed dunnart) and Planigale gilesi (Giles' planigale), without and with implanted transmitters. In both species maximum running speed was not affected by the transmitters, whose mass ranged from 6.4% to 14.1% of body mass. Further, relative transmitter mass was not correlated with maximum running speed. Consequently, transmitters well above 5% of body mass need not affect locomotor performance of small terrestrial mammals.

Lower jaws (containing the teeth), eyes, and skin samples were collected from harp seals (Pagophilus groenlandicus) in the southeastern Barents Sea for the purpose of comparing age estimates obtained by 3 different methods, the traditional technique of counting growth layer groups (GLGs) in teeth and 2 novel approaches, aspartic acid racemization (AAR) in eye lens nuclei and telomere sequence analyses as a proxy for telomere length. A significant correlation between age estimates obtained using GLGs and AAR was found, whereas no correlation was found between GLGs and telomere length. An AAR rate (k_Asp) of 0.00130/year ± 0.00005 SE and a D-enantiomer to L-enantiomer ratio at birth (D/L₀ value) of 0.01933 ± 0.00048 SE were estimated by regression of D/L ratios against GLG ages from 25 animals (12 selected teeth that had high readability and 13 known-aged animals). AAR could prove to be useful, particularly for ageing older animals in species such as harp seals where difficulties in counting GLGs tend to increase with age. Age estimation by telomere length did not show any correlation with GLG ages and is not recommended for harp seals.

Quantitative magnetic resonance (QMR) is a new technology for measuring body composition of live, nonanesthetized animals (fat mass, lean mass, and total body water) in 4 min or less. We conducted a validation study to compare QMR body composition analysis of 3 species of bats (mass range 5.77–31.30 g) with traditional chemical extraction. In addition to scans of live animals, we tested the effectiveness of QMR for salvaged specimens (bats killed by wind turbines) and the effects of carcass temperature. Our analysis indicates that QMR body composition analysis is effective for live and salvaged animals. Frozen carcasses could not be analyzed, but results were not dramatically affected for specimens at 4°C and 37°C. QMR analysis eliminates the need to euthanize animals to determine body composition precisely, allows rapid and efficient data collection, and makes it possible to follow individuals longitudinally through time.

The Nearctic has been recognized as a biogeographic region since the 19th century. We analyzed distributional patterns of the mammals inhabiting North and Central America, from Alaska to Panama, to delimit the boundaries of the Nearctic region. We performed 6 optimality analyses, using a grid of 4° latitude–longitude, based on families, genera, species, and combinations of these. The analysis of the matrix with the 3 taxonomic levels yielded better results in terms of the largest number of endemics and the best delimitation of the Nearctic region. We also found 3 patterns—western, eastern, and northern—within the region that coincide partially with previous biogeographic characterizations. Although mammals seem to represent appropriate taxa to delimit this region, we conclude that a more robust delimitation might be obtained by analyzing other plant and animal taxa.

The importance of hybridization in animal evolution has become controversial. Gene flow between divergent taxa can strongly influence processes of great interest to evolutionary biologists, such as speciation and adaptation. Mitochondrial DNA (mtDNA) introgression is a commonly observed, yet particularly poorly understood consequence of hybridization between divergent taxa. Several known cases of mtDNA introgression exist that are heterogeneous in time and space, and it is unknown whether this represents the influence of extrinsic factors, such as selection and demographic fluctuation, or more intrinsic ones, such as cytonuclear interactions or the mosaic evolution of reproductive isolation. It is usually assumed, on the basis of the apparent lack of hybrids at zones of contact, that this phenomenon is unaccompanied by further admixture at nuclear loci, although this assumption rarely is tested. We present an analysis of population structure and gene flow across a zone of mitochondrial introgression between 2 nonsister species of chipmunk (Sciuridae: Tamias). We examined patterns of variation in 11 nuclear markers (10 microsatellites and 1 sequence-based marker) and compared them with previously identified patterns of mtDNA variation. We found little evidence of nuclear gene flow but some correspondence of introgression with microsatellite population structure. This work suggests that a complex interaction of ecological and genetic factors could have structured introgression of mtDNA in this system.

We lack critical information for oceanic archipelagos worldwide related to the origin and status of insular faunas. In southwestern Alaska, in particular, a need exists to tease apart whether specific insular populations are naturally occurring or are the result of exotic introductions by humans. We analyzed variation in mitochondrial sequences of the cytochrome-b gene and 8 nuclear microsatellite loci across 215 individuals representing 17 populations (12 insular) to refine our understanding of the history of the previously identified Southwest clade of arctic ground squirrels (Spermophilus parryii). We found significant geographic structure that suggests long-term isolation and diversification (Ushugat Island and Cold Bay), but we also documented closely related populations that are likely the result of human-mediated introductions. The latter instances (Kavalga and Unalaska islands) corroborate reports from early Alaska explorers.

The collared peccary (Pecari tajacu) is a social species that recently has expanded its historical range, yet little is known of its dispersal behavior at the population or biogeographic level. We used autosomal and cytoplasmic markers to assess whether the genetic variation among 4 populations in Texas retains a signal of historically recent founding events. Genetic differentiation based on mitochondrial DNA (mtDNA) haplotype frequencies (F_ST) among these 4 populations was substantial. The mtDNA haplotype mismatch distributions indicate that P. tajacu recently has expanded its range across Texas; however, microsatellite-based standard analyses of molecular variance (AMOVAs) and pairwise F_ST estimates indicated little variation among populations, suggesting that dispersal is accomplished primarily by males. We also tested the alternative power of mtDNA haplotype or microsatellite genotype distribution patterns to detect a sex bias in instantaneous short-distance dispersal. Sex-specific hierarchical AMOVAs of mtDNA haplotype distributions (based on data from the most genetically diverse population) yielded significantly larger female-specific fixation index values compared to males, indicating a male instantaneous dispersal bias; however, variation in microsatellite frequency distribution was not partitioned in a sex-specific manner. Also, when sex-specific pairwise F_ST/(1 − F_ST) among herds was regressed against the log of the distance between each pair of herds, we found no significant effect of distance for either sex and no sex-specific difference using other microsatellite-based analyses (mean sex-specific relatedness, r, or F_ST). We conclude that sampling scale limits microsatellite-based methods of detecting instantaneous dispersal sex bias, especially when gene flow is substantial and microsatellite polymorphism is modest (<20 alleles/locus). These results indicate that mtDNA can be used to infer instantaneous dispersal behavior for both sexes in cases where microsatellites have proven insufficient.

Despite the fundamental nature of the home range to the biology of a species, aspects of its size, shape, and structure are not well defined in certain groups, such as subterranean rodents. These rodents, characterized by limited individual mobility and a patchy distribution of local populations, generally defend multipurpose territories in which breeding and foraging take place, increasing the chances for trade-offs among factors of habitat quality. The present study assessed the home-range size and shape of 2 species of tuco-tucos, Ctenomys australis (300–600 g) and C. talarum (100–180 g), using radiotelemetry in an area where they occur in sympatry, and explored the factors that could influence space use in these subterranean rodents. Home-range size (95% adaptive kernel) of C. australis (1,282.22 ± 1,014.83 m²) was ∼19-fold larger than that of C. talarum (66.69 ± 22.34 m²). The area covered daily by C. australis represented only about 9% of the total home-range size estimated by radiotelemetry in this study and was almost twice as large as that of C. talarum, but the area covered by the latter species represented an average of 35% of its total home-range size. Total aerial and subterranean plant biomass, plant cover, and soil hardness were significantly higher in the habitat occupied by C. talarum. Contrary to expectation, body size was not the predominant factor explaining intra- and interspecific variation in home-range size. We discuss how variation in food availability in space and time and differences in the intensity of polygyny could be more important factors shaping home-range size in this genus of subterranean rodents.

Resolving phylogenetic relationships within Vespertilionidae has been difficult, with large data sets (>100 taxa, >7 kilobases) resolving portions of the phylogeny but leaving intertribal relationships within the Vespertilioninae unresolved. As a result the evolutionary history of the most speciose chiropteran family is largely unknown. The presence of short internodes followed by long terminal branches relative to other chiropteran phylogenies suggests that evolutionary rates of DNA substitution and lineage diversification could be inhibiting phylogenetic resolution. To test this hypothesis we obtained sequences of the mitochondrial DNA (mtDNA) 12s rRNA, tRNA^VAL, and 16s rRNA, and the nuclear exon RAG2, resulting in more than 3 kilobases of digenomic DNA sequence data for representatives of all subfamilies and tribes within Vespertilionidae and Phyllostomidae, a family of bats that radiated at approximately the same time as Vespertilionidae. Analyses revealed that substitution rates for Vespertilionidae were significantly higher than those for Phyllostomidae, with the majority of fast-evolving lineages found within Vespertilioninae. Cladogenesis analyses characterized the vespertilionid radiation as compressed toward the root, with a rapid initial diversification, but the phyllostomid diversification was much more gradual. We suggest that ecological differences between tropical and temperate environments could have influenced diversification rates for Vespertilionidae and Phyllostomidae.

Loxodontomys micropus is a rodent that is widely distributed in Andean and Patagonian Argentina and Chile. This range covers a heterogeneous area that has been influenced by geologic and palaeoclimatic events, such as the glaciations during the Neogene. To investigate the genetic structure, phylogeographic pattern, and biogeographic history of this sigmodontine rodent we analyzed a 801-base-pair fragment of the mitochondrial genome (cytochrome-b gene) of 87 specimens from 24 localities from Argentina and Chile. Results indicate that L. micropus has a shallow genealogy that is geographically structured and is a taxon characterized by an historical population expansion. We discuss the distribution of the genetic variation of L. micropus in relation to population history and the concordance with other codistributed sigmodontine rodents. On the basis of molecular evidence, we suggest that the L. pikumche, corresponding to the second extant species of the genus, could be a junior synonym of L. micropus.

The 2 subspecies of mink (Neovison vison letifera and N. v. mink) in Illinois were characterized early in the 20th century; however, quantifiable morphological distinctions between the 2 subspecies remain unclear. Illinois biogeography, and the influence of glaciations on animal populations, might explain the distinctions between the 2 mink subspecies. We evaluated sexual dimorphism within each subspecies and morphologic variation between subspecific populations. Oral, facial, and braincase regions were defined by 22 dimensions. Sexual dimorphism was present in both subspecies of mink. Data were adjusted for sex differences and tested for differences between subspecies using analysis of variance and multivariate analysis of variance. Cranial dimensions differed significantly between N. v. letifera and N. v. mink. Cranial dimensions distinguish individuals of the 2 geographically distinct subspecies; however, an intergradation zone might be present. The results are consistent with population response to glaciations and subsequent expansion, however, further genetic testing is necessary to test this historical biogeography of N. vison.

Recent molecular phylogenetic studies of Southeast Asian shrews (Crocidura) suggest that Crocidura mindorus, as currently defined, is diphyletic. The species is reported from Mindoro (type locality) and Sibuyan islands in the Philippines, each of which has been isolated from other land masses over considerable geological timescales. We examined morphological evidence to determine whether the Mindoro and Sibuyan populations represent distinct, endemic species. We found that the two populations differ in discrete and mensural characters. This evidence, combined with previous molecular phylogenetic studies, confirms that the Sibuyan population is an isolated, independently evolving lineage, and we formally describe it as a new species, Crocidura ninoyi.

The Davis Mountains cottontail, Sylvilagus robustus, is morphologically different from the eastern cottontail, S. floridanus, but previous genetic analysis of mitochondrial DNA data did not recover 2 genetically distinct groups. Our study used a nuclear DNA fingerprinting technique, amplified fragment length polymorphism (AFLP), to test the hypothesis that S. robustus is genetically distinct from S. floridanus. We tentatively considered any individual collected at an elevation >1,400 m as S. robustus and later confirmed our identifications with morphological or genetic data, or both. Principal component and discriminant function analyses of 6 previously published cranial measurements confirmed morphological distinctiveness. For genetic analyses we analyzed 273 AFLP fragments from 20 individuals of S. robustus and compared them to 16 S. floridanus, 4 S. audubonii, and 1 S. obscurus. Results from phylogenetic and population genetic analyses suggest a significant lack of gene flow between the 2 species. Together, these data support recognition of S. robustus as a separate species.

We used quantitative fatty acid signature analysis (QFASA) to predict the long-term diet of New Zealand (NZ) sea lions (Phocarctos hookeri) incidentally caught in the NZ arrow squid (Nototodarus spp.) fishery. The QFASA model used fatty acid (FA) profiles based on 82 blubber samples of NZ sea lions bycaught between 2000 and 2006. First, the model was optimized by a series of simulations for which 1 model parameter—6 different sets of calibration coefficients (CCs) from different pinniped species and feeding regime, 2 sets of FAs, and the consideration of individual prey values, or mean prey values—varied each time. The best-fit parameters were those giving the lowest Kullback–Liebler distance values. Second, these parameters were used in a model to estimate the diet of NZ sea lions. QFASA was highly sensitive to the set of CCs applied. Across years the most important prey estimated with the best-fit CCs were southern arrow squid (Nototodarus sloani, 18–28% mass), hoki (Macruronus novaezelandiae, 10–27% mass), rattails (Macrouridae, 7–27% mass), and possibly scampi (Metanephrops challengeri, 1–19% mass). Despite the uncertainty on the accuracy of the match between the best-fit CCs used and the true FA metabolism of NZ sea lions, the variation of prey estimated among years was highly consistent with the trends of commercial catches during the same period, providing some confidence in the present QFASA predictions. The most important estimated prey were demersal species living mainly at depths >200 m that NZ sea lions encounter on the slopes of the Auckland Islands shelf. Our study emphasized the importance of these areas for bycaught NZ sea lions over the 1st half of the lactation period.

The purpose of this study was to determine androgen and glucocorticoid (GC) hormonal patterns in male giant pandas (Ailuropoda melanoleuca) by monitoring gonadal and adrenal metabolites in feces. Initial validation experiments demonstrated comparable excretory patterns in urine versus feces for both androgen and GC measures. Matched urinary and fecal androgen and GC were correlated strongly with each other in a single male that was assessed over 2 years. A single pharmacological injection of adrenocorticotropic hormone caused a 15-fold GC increase in feces above baseline within 10 h, a peak at 12 h, and a return to baseline at 20 h, demonstrating the biological relationship between adrenal activation and GC excretion. Longitudinal androgen and GC excretory profiles in male giant pandas housed at North American (n  =  2) and Chinese (n  =  3) facilities were similar, with fecal androgens generally exceeding baseline coincident with the onset of the 5-month annual breeding season (January–June), after which values returned to nadir. Similarly, fecal GC excretion increased during the breeding season but was baseline thereafter. Fecal androgen and GC in a single male monitored through transition from subadult to sexual maturity also occurred in parallel. In this individual, basal fecal androgen and GC increased 88% and 66%, respectively, from 5 to 6 years of age. Collectively, these data demonstrate seasonal variations in gonadal activity in the giant panda by measuring androgen metabolites in feces, with elevations consistently occurring from January through June before a return to baseline for ∼4–6 months. Findings also reveal a similar temporal rise in adrenal GC patterns associated with breeding season onset, perhaps a mechanism to enhance metabolism, maximize body energy stores, and provide a competitive advantage in achieving mating opportunities. Examination of data from a single male suggests that the ability to produce these seasonal androgen and GC elevations is age dependent and occurs coincident with puberty.

Ontogenetic allometries of craniomandibular and dental features linked to digging were analyzed in 5 species of the South American subterranean rodent Ctenomys (tuco-tucos). With the exception of upper incisor procumbency, variables showed high correlation with overall skull size. In particular, craniomandibular variables related to the production of bite forces at the incisors showed near-geometric similarity during postnatal growth and interspecific changes in early developmental stages resulting in different starting forms (lateral transposition). Such an interspecific pattern of change is similar to one previously reported to occur among living and extinct ctenomyid genera. These results suggest more evolutionary flexibility for changes in early ontogenetic stages and allow rejection of the hypothesis that interspecific shape differences in the skull of Ctenomys would be associated with differences in size alone.

Dyck and Kebreab (2009) analyzed the required summer intake of arctic char, ringed seal blubber, and berries that polar bears must consume to maintain their body mass during a summer ice-free period. Their calculations of required intake were based on the amount of body mass lost by fasting bears in western Hudson Bay. However, fasting polar bears are in a low metabolic state with energetic requirements less than those of an active, feeding bear. Estimates of energy consumed by captive brown bears were 4–4.5 times higher than the estimates used by Dyck and Kebreab for similar diets. Furthermore, the authors' portrayal of the availability of these resources is misleading because they do not acknowledge limited accessibility of arctic char due to their limited anadromy and predominant occurrence in streams too deep to facilitate efficient capture by polar bears; effects of large interannual fluctuations in the availability of berries or competition with other frugivores; high energetic requirements associated with lengthy foraging times required to locate and consume sufficient fruit; and data from southern Hudson Bay, western Hudson Bay, and the southern Beaufort Sea that document continued declines in several biological indices over the past several decades despite the authors' suggested availability of terrestrially based food resources. Based on current information, arctic char, berries, and ringed seals in open water do not appear to be food sources with the potential to offset the nutritional consequences of an extended ice-free period.

The American Society of Mammalogists herein provides revised guidelines for personnel working with rodents potentially infected with viruses that cause hantavirus pulmonary syndrome (HPS) in humans. We also clarify that previously published guidelines, including those of the United States Centers for Disease Control and Prevention (CDC), were not intended to apply to field-workers conducting nonviral-based research on rodents. Unfortunately, institutional animal care and use committees and other safety officers have assumed that current CDC recommendations are requirements for conducting safe field research. They then have misapplied the original CDC recommendations to field researchers conducting behavioral, ecological, taxonomic, and other research, making field research increasingly and unnecessarily difficult. Herein, we provide guidelines that have been modified from those published by the CDC to incorporate new information about HPS risk and to better match the level of personal protection to the level of risk associated with a wider array of field activities.