We describe a new living genus and species of Sigmodontinae currently only known from the Brazilian National Park Sempre Vivas, Minas Gerais State. This rodent is characterized by a unique combination of traits that include, among others, a long tail, with its distal tip (approximately 2.5 to 5 cm) entirely white; skull with domed profile; long rostrum with an incipient rostral tube; and noticeable small brachyodont molars with reduced mesolophs and mesostyles present on the 1st and 2nd upper molars. Cladistic analyses of molecular (1 mitochondrial and 1 nuclear marker) and morphological characters indicate that the new genus belongs to the Phyllotini and is sister to the remainder genera of this tribe. However, contrary to other known phyllotines, the new genus shows vestigial mesolophs and mesostyles. Phyllotines are widespread in open areas, in particular desert and semideserts, mostly in the western portion of South America. The new genus described herein expands the diversity of the tribe and suggests an ancient event of diversification in eastern Brazil.

Describimos un nuevo género y especie de Sigmodontinae actualmente sólo conocido para el Parque Nacional brasilero Sempre Vivas, Estado de Minas Gerais. Este roedor se caracteriza por una combinación única de rasgos que incluyen, entre otros, una cola larga con su porción distal (ca. 2,5 a 5 cm) enteramente blanca; cráneo con perfil abovedado; rostro largo con tubo rostral incipiente; molares braquiodontos notablemente pequeños con pequeños mesolofos y mesostilos presentes en los primeros y segundos molares superiores. Análisis cladísticos de caracteres moleculares (un marcador mitocondrial y un marcador nuclear) y morfológicos indican que el nuevo género pertenece a los Phyllotini y es hermano de los restantes géneros de la tribu. Sin embargo, contrariamente a los otros filotinos conocidos, el nuevo género muestra mesolofos y mesostilos vestigiales. Los filotinos están ampliamente distribuidos en zonas abiertas, en particular en desiertos y semidesiertos, mayormente en la porción occidental de América del Sur. El nuevo género aquí descripto expande la diversidad de la tribu y sugiere un antiguo evento de diversificación en Brasil oriental.

We document the existence of a new species of shrew (Soricomorpha, Soricidae, Crocidura) in West Java, Indonesia, using both morphological and genetic data. Relative to other Southeast Asian Crocidura, the new species is medium-sized with a slender body and long tail, which together readily distinguish it from all other Javan shrews. Morphological differences between the new species and Crocidura paradoxura, another long-tailed shrew that is endemic to Sumatra, are subtle, but genetic differences suggest a long, independent evolutionary history. This description brings to 5 the total number of species of Crocidura recognized from Java. All 5 species are endemic to the island and as many as 4 occur in syntopy. Further investigation is needed to document geographical ranges of shrew species on Java, especially along the island's east–west climatic gradient, where previously proposed subspecies boundaries may be coincident with transitions in precipitation patterns.

This study presents the most comprehensive systematic revision of the genus Lutreolina to date, by means of genetic (mitochondrial DNA of 22 specimens) and morphologic (assessment of 262 specimens) evidence. Molecular analyses were based on cytochrome-b gene sequences from 22 individuals collected at 18 localities from Argentina, Bolivia, Brazil, Paraguay, and Uruguay, which are currently allocated to L. crassicaudata. Results indicate that Lutreolina has sharp phylogeographic structure, with 2 reciprocally monophyletic groups (2.7% divergent, whereas intraclade variation is minimal) occurring east and west of the Dry Chaco, where Lutreolina is absent. The eastern clade includes populations from eastern Paraguay, northeastern central Argentina, southern Brazil, and Uruguay. These populations were traditionally allocated to the subspecies L. c. crassicaudata and L. c. paranalis, whose monophyly is not supported in our study. Therefore, eastern populations are all assigned here to the nominotypic subspecies. The western clade is restricted to montane Yungas forests of northwestern Argentina and southern Bolivia, a very different environment from those inhabited by Lutreolina elsewhere (i.e., lowland savannah grasslands). The populations from the Yungas also are morphologically distinct, in size, shape, and in discrete characters of the skull and dentition. We found that these populations belong to a different species than that of the eastern lowlands. Because no taxonomic name is available to apply to these populations, we name and describe a new species of lutrine opossum to encompass them.

Este estudio es la revisión taxonómica más comprensiva del género Lutreolina. Se analizaron datos genéticos (ADN mitocondrial de 22 especimenes) y morfológicos (evaluación de 262 especimenes). Los análisis moleculares emplearon secuencias del gen que codifica para el citocromo b de 22 individuos colectados en 18 localidades de Argentina, Bolivia, Brasil, Paraguay y Uruguay; actualmente estas poblaciones se incluyen en L. crassicaudata. Los resultados indican que Lutreolina tienen una marcada estructura filogeográfica, con 2 grupos recíprocamente monofiléticos (2,7% divergentes entre si y con mínima variación interna) distribuidos, respectivamente, al este y oeste del Chaco seco, en el cual Lutreolina no se distribuye. El clado oriental incluye poblaciones de Paraguay oriental, centro y noreste de Argentina, sur de Brasil y Uruguay. Estas poblaciones tradicionalmente fueron referidas a las subespecies L. c. crassicaudata y L. c. paranalis, cuya monofilía no es corroborada en este estudio. Por lo tanto, todas las poblaciones del clado oriental son aquí asignadas a la subespecie nominotípica. El clado occidental se distribuye en las selvas de montaña o Yungas del noroeste de Argentina y suroeste de Bolivia, un ambiente marcadamente diferente del habitado por Lutreolina en otras áreas (i.e., pastizales en tierras bajas). Las poblaciones de las Yungas son también morfológicamente distintas, tanto en tamaño y forma como en caracteres discretos del cráneo y la dentición, de aquellas de las áreas abiertas del este. Por lo tanto, concluimos que las poblaciones de las Yungas pertenecen a una especie diferente de aquella que habita las tierras bajas del este. Debido a que no hay un nombre disponible para las poblaciones de las Yungas, nominamos y describimos una nueva especie de comadreja para contener a estas poblaciones.

The present study aims to depict the overall pattern of the history of the North African dipodil, Gerbillus campestris, in the northern Sahara. More specifically we document whether or not Pleistocene refugia, the Sahara desert, and the Moulouya River structure patterns of diversity in this species. The phylogenetic relationships among populations were determined by analyses of the cytochrome-b gene in 100 specimens collected in 5 countries (Morocco, Algeria, Tunisia, Mali, and Niger) and 27 localities. Our study highlights a complex phylogeographic pattern for G. campestris in North Africa, with 9 phylogenetic lineages differing by up to 2.5% of sequence divergence. Most of these lineages are allopatric, except in Morocco where 2 lineages are overlapping in the south. These genetic lineages probably arose during the successive cycles of cooling and warming climatic conditions that characterized the end of the Pleistocene, caused by the combined effects of habitat changes and marine transgressions. The divergence between Saharan and Moroccan populations occurred during a period of aridification at the end of the Pleistocene. The Moulouya and the Bou Regreg rivers also seem to be major biogeographical barriers to gene flow in this species.

Peromyscus schmidlyi is an endemic rodent from the forested highlands of the Sierra Madre Occidental (SMO) in Mexico. Using 2 genetic markers (cytochrome-b and D-loop) we explored the possible relationship between a recently proposed division of pine–oak forests of the SMO into specific regional communities and patterns of genetic and morphometric variation in P. schmidlyi. We found no genetic structure or significant relationships between either marker and ecological or morphometric variation. Phylogenetic and haplotypic network analyses revealed no geographically structured clusters; phylogenetic trees were shallow and networks were star-shaped. No signal of selection was detected for either marker at the local level. All available evidence suggests that the current distribution of P. schmidlyi is the result of dispersal into the SMO followed by rapid population expansion throughout the area in the late Pleistocene, following the glacial cooling of the SMO highlands.

Peromyscus schmidlyi es un roedor endémico de los bosques de pino–encino de las partes altas de La Sierra Madre Occidental (SMO), México. Utilizando dos marcadores moleculares (Citocromo B y D-loop), se evaluaron las posibles relaciones entre la variación genética y morfométrica de las poblaciones de P. schmidlyi y la recientemente propuesta regionalización de las comunidades vegetales de las partes altas de la sierra. No encontramos estructura genética, ni relaciones significativas entre la variación genética de ningún marcador y la variación ecológica o morfométrica. El análisis de filogenias y redes haplotípicas no reveló grupos significativos geográficamente estructurados, más bien, lo que se obtuvo fueron árboles con poca profundidad y redes en forma de estrella. Asimismo, las pruebas de neutralidad por localidad fueron no significativas y no se encontró evidencia de selección en ninguno de los marcadores. La evidencia disponible sugiere que la distribución actual de P. schmidlyi es resultado de dispersión seguida de una rápida explosión de la población sobre las partes altas de la SMO a finales del Pleistoceno, como resultado del enfriamiento glacial de las mismas.

Understanding ecological traits of species associated with vulnerability to habitat fragmentation is important for the development of effective conservation efforts. However, few studies have examined ecological correlates of vulnerability to fragmentation among tropical small mammals at fine spatial scales. Here we use random forests and regression tree models to identify ecological correlates of vulnerability to fragmentation among terrestrial small mammal species across 2 networks of forest fragments in the East and West Usambara Mountains, Tanzania. Small mammal species vary considerably in their vulnerability to fragmentation as assessed by species occupancy and change in abundance. Random forests models indicate that matrix use is the highest-ranked predictor of vulnerability to fragmentation with small mammal species that do not use or use few matrix habitat types, being more vulnerable to fragmentation than species that use all adjacent matrix habitat types. Our results emphasize the importance of local-scale approaches for designing conservation strategies for Afrotropical small mammal species.

Recent work with least chipmunks, Neotamias minimus, has identified a novel seed preparation process. N. minimus begins by hulling seeds and then creating a thick saliva-coated cluster that hardens once expelled. Scattered and undefended, these “bolus” caches are at risk for theft. However, the behaviors involved in the creation of a bolus may confer protection against such pilferage. In a series of laboratory experiments with sunflower seeds, we found that both the hulling and saliva-clumping processes significantly reduced pilfering of these caches by conspecifics and a competitor, Tamias striatus, under 3 cache depth conditions.

We discovered hard structures that resembled bone in the penis of 20 specimens of male American pikas (Ochotona princeps) from the Rocky Mountains of southwestern Alberta, Canada. Histological sections of these structures showed features consistent with cortical bone and osteocytes, and scanning electron microscopy analyses indicated peaks in calcium and phosphorous. The anatomical positioning, internal texture, and elemental composition indicate that the structures are bacula. The presence of a baculum in O. princeps demonstrates that there is a greater phylogenetic distribution of this feature among Mammalia than commonly recognized, and it indicates that the absence of a baculum is not a derived character state for Lagomorpha.

We investigated the social interactions and spatial organization of the Japanese badger (Meles anakuma) using radiotelemetry. Fifty-two individuals (29 males and 23 females) were trapped and marked (tattooed) between 1990 and 1997 from a population with a density of 4 individuals/km². Twenty-one of these individuals were subsequently radiotracked. The average home-range size of males expanded from an average of X̄ = 33.0 ha ± 18.1 SD in the nonmating season to 62.6 ± 48.2 ha in the mating season, and was significantly larger than the home-range size of females (15.2 ± 6.3 ha in the mating season; with a lack of data on individual female home-range–size change between seasons). We posit that this range expansion by males occurred to encompass the key resource of estrous females during the breeding season; thus, males exhibited a flexible home-range strategy. Females with cubs had home ranges exclusive of other adult females, configured around areas rich in food resources, indicative of intrasex territoriality. This obstinate strategy, under the constant territory size hypothesis, likely serves to ensure a reliable supply of food resources (as determined by resource dispersion) for cub rearing. Eleven of 36 cubs born during the study remained in their natal range until the next spring and we observed 1 of 5 instances of matriarchal territory inheritance. Microsatellite DNA analysis indicated that the basic social unit was composed of the mother and cub(s), with less-related males providing gene flow. This mother–cub unit, with the retention of nonbreeding juveniles or young adults, or both, along with the loose affiliation of breeding males, informs understanding of the development of group-living, subject to ecological circumstances, in the genus Meles and broadens understanding of the evolution of carnivore sociality.

Concentration of fecal nitrogen has been used widely as an indicator of dietary quality for free-ranging ruminants. Differences in digestive function between species of dimorphic ungulates render interspecific comparisons of fecal nitrogen unreliable; however, whether intraspecific sexual differences in digestive function also bias this nutritional index is unknown. Our objective was to compare sex-specific variation in concentration of fecal nitrogen using male, nonlactating female, and lactating female white-tailed deer (Odocoileus virginianus) on high- and low-quality diets. During weekly trials over spring and summer (2008–2009), we monitored intake rates, collected feces twice daily, and used micro-Kjeldahl procedures to determine percent fecal nitrogen. We also determined nitrogen content of feces following a neutral detergent fiber (NDF) rinse during pre-, peak , and postlactation. Fecal nitrogen reflected general differences in dietary quality between diets; however, fecal nitrogen of lactating females in both dietary groups was lower than for males or nonlactating females throughout lactation. Nitrogen concentration following an NDF rinse also was lower for lactating females during peak lactation. We hypothesize that the remodeling of the digestive tract and increased rumination by lactating females may enhance their ability to extract nitrogen from their forage. These adjustments may expand the foraging options of lactating females by increasing their ability to process low-quality foods, but also affects the interpretation of fecal nitrogen during the season of lactation.

Success or failure of any stage of reproduction is generally related to maternal characteristics and environmental influences. In addition, postreproductive body condition of females should be a function of effort allocated to reproduction. Using data on > 800 female white-tailed deer (Odocoileus virginianus) harvested during 4 years on Anticosti Island (Quebec, Canada), we investigated factors affecting reproductive status, from ovulation to weaning, and measured the resulting effect on female body condition. The probability of ovulation (single or double) increased with female age, but weaning success was unrelated to age. Female reproduction was determined by climatic conditions in each season and the availability of preferred habitat, but high density only affected young primiparous females. More specifically, snowy autumns decreased ovulation rate, dry springs disfavored the production of twins, and cold and snowy winters decreased weaning success. Habitat with high summer plant biomass favored both 1st ovulation and weaning success. We suggest that restricted forage conditions encountered during their 1st year of life selected for higher-quality females, that is, females with fewer reproductive pauses and higher weaning success. Reproductive effort generally decreased female body condition, which was lower in lactating than nonlactating females. We suggest that twin production occurred in higher-quality females because, although females conceiving twins had reduced fat reserves, they maintained larger body size and higher muscular mass than mothers of singletons. Our results demonstrate that females adjusted reproductive effort according to seasonal environmental conditions, probably to minimize the consequences of reproduction on body condition, a proxy of reproductive cost.

The recently diminished caribou (Rangifer tarandus) population in insular Newfoundland, Canada, has been severely limited by predation on newborn calves. These neonates are patchily distributed on the landscape; therefore, to adequately understand predator–prey interactions, the temporal and geographic extent of the distribution of caribou calves must be identified so that current areas with calves can be differentiated from areas without calves. We used telemetry locations of 309 caribou calves and 100 adult females from 4 herds, 2008–2010, to estimate the spatiotemporal distribution of caribou calves during the time when they were most vulnerable to predation, to evaluate the predictability of the calf resource among years, and to assess the degree of aggregation during calving. Patterns of calf distribution were predictable in time and space from year to year, with an average distributional overlap of 68% between years. The dispersion of female caribou during calving varied among herds from highly aggregated (8% and 20% of herd range) to more dispersed (50–70% of herd range). Postcalving (up to 9 weeks) distributions also varied among herds; the 2 more-dispersed herds remained sedentary, whereas both highly aggregated herds migrated away from their calving grounds at the end of June. The most-aggregated herd remained so as it migrated from its calving ground, whereas the less-aggregated herd spread out and moved in a variety of predictable directions. Dispersion and movement patterns varied with forest cover; herds with less forest cover in their range were more aggregated and migratory than herds with more forest cover.

Black rhinoceroses (Diceros bicornis) defecate in middens and frequently use sharp kicking motions to scatter their feces in large and conspicuous scrapings. Although these fecal markings are believed to be advertisements to conspecifics, the type of information that might be encoded has not been investigated. Because of the secretive nature of black rhinos, we used camera traps to identify individuals scraping their feces in 2 sections of Addo Elephant National Park, South Africa. We collected fecal samples (n = 137; July 2009–November 2010) from known individuals (captured on photo), gathered data about fecal scrapings (e.g., length and location), and analyzed samples for concentrations of fecal progestagen and androgen metabolites. We predicted that the physical and chemical aspects of the fecal scrapings were related to the sex, age, and reproductive state (e.g., fecal gonadal metabolite concentration) of the black rhinos. Lengths of fecal scrapings increased with age for both sexes and were negatively related to concentrations of fecal progestagen metabolites for females. Males scraped more than females, whereas females were more likely to scrape next to a bush. Similar to other territorial species, black rhino fecal markings seemed to advertise the territories of adult males and communicate about the sexual status of the female.

Despite a now-extensive literature on sex allocation, facultative sex allocation in mammals remains controversial. We studied the complete birth-sex record of a black rhinoceros (Diceros bicornis minor) population from its reintroduction in 1986 through 2008. Neither explicit models of birth sex as Bernoulli trials nor mixed-model logistic regression yielded evidence for an influence on birth sex of birth sequence, maternal identity, year of conception, rainfall, population size, maternal age, or adult sex ratio despite a small female-biased population birth sex ratio that nevertheless appears to be unusual for black rhinoceros. One interpretation of our results is that our study population did not facultatively control birth sex, either because black rhinoceros cannot or because environmental and demographic circumstances did not elicit conditions that favor pronounced adaptive control of birth sex in this population. Alternatively, variation in sex allocation could have occurred in a manner not captured by our modeling or at a scale we could not probe. If the observed female bias is not purely stochastic, it may result from the perturbed age structure of the introductions, which was biased toward subadults.

Age and sexual maturity have not previously been studied in Australian bottlenose dolphins. These were investigated in 57 male Indo-Pacific bottlenose dolphins (Tursiops aduncus) collected opportunistically in South Australia between 1989 and 2011. Age was estimated by counting growth layer groups in dentine tissue. Formalin-fixed testes plus epididymides were weighed, measured, and subsampled for histological analysis. Stage of spermatogenesis, presence of spermatozoa, testis tubule size, seminiferous tubule wall and tunica thickness, and relative amount of interstitial tissue were noted. Immature testis tubules contained only Sertoli cells and spermatogonia and had mean testis weights < 83 g, lengths < 190 mm, and tubule diameters < 98 μm. Testes of Active dolphins had spermatozoa, testis plus epididymis weights between 250 and 1,025 g, testis lengths between 164 and 292 mm, and mean tubule diameters > 84 μm. Regressed/pathological dolphins had testis weights (199–280 g), testis lengths (195–230 mm), and tubule diameters (59–130 μm) larger than Immature males and on average less than Active males. Seminiferous tubule wall thickness also separated Regressed/pathological male (X̄ = 14.9 μm) from Immature male (X̄ = 2.3 μm) testes. Sexual maturity in male Indo-Pacific bottlenose dolphins was attained between body lengths of 208 and 220 cm and body weights of 90 and 115 kg. Some males (20%) were sexually but not physically mature as determined by fusion of vertebral epiphyses. All physically mature males were sexually mature. The youngest sexually mature dolphin was 12 years old and the oldest immature male was 15 years, but samples were limited in the 8- to 12-year range. Testicular regression has not previously been reported in Tursiops spp. The 3 regressed males from South Australia had gross and histological evidence of organ pathology, including in the testes, suggesting that their reproductive status was related to ill health, rather than seasonal or individual cycling of function or senescence. The implications of heavy-metal toxicity on male Indo-Pacific bottlenose dolphin reproduction is discussed.

Effective conservation efforts often depend on accurate identification of habitat requirements. Studies that identify habitat requirements for animals typically investigate use of structural habitat (vegetation) instead of functional habitat (conditions for biological fitness). The spatial scale of data could bias the match between functional and structural habitat because broadscale structural habitat maps exclude small habitat patches (inclusions) and broadscale location error can bias estimates of habitat use. To investigate how spatial scale affects the match between functional and structural habitat, we backtracked American marten (Martes americana) and fisher (Pekania [formerly Martes] pennanti) movement paths during winter and compared results from selection and tortuosity analyses conducted with broadscale (4 ha) and fine-scale (0.02 ha) structural habitat data. Functional habitat (rest sites and prey kill sites) occurred disproportionately in hemlock–cedar. Fine-scale structural habitat data detected greater selection and tortuosity within hemlock–cedar by traveling martens, but broadscale structural habitat data did not, which demonstrates that combining fine-scale location data with fine-scale structural habitat data improves the match between functional and structural habitat and understanding of habitat requirements. Selection and tortuosity indexes were poorly correlated, indicating that factors other than structural habitat influenced movement patterns. Within-stand structural habitat heterogeneity is important to martens and fishers, especially when heterogeneity includes mature conifer inclusions within primarily deciduous forests. Broadscale data may identify structural habitat associated with required types, rather than required habitat itself, when functional habitat corresponds with landscape features such as inclusions.

Camera-trapping surveys, in combination with traditional capture–recapture or spatially explicit capture–recapture techniques, have become popular for estimating the density of individually identifiable carnivores. When only a portion of the population is uniquely identifiable, traditional and spatial mark–resight models provide a viable alternative. We reanalyzed a data set that used photographic capture–recapture methods to estimate the densities of pumas (Puma concolor) across 3 study sites in Belize, Argentina, and Bolivia using newer, more-advanced modeling including spatial and nonspatial mark–resight techniques. Additionally, we assessed how photo identification influenced density estimates by comparing estimates based on capture histories constructed by 3 independent investigators. We estimated the abundances of pumas using mark–resight models in program MARK and then estimated densities ad hoc. We also estimated densities directly using spatial mark–resight models implemented in a Bayesian framework. Puma densities did not vary substantially among observers but estimates generated from the 3 statistical techniques did differ. Density estimates (pumas/100 km²) from spatial mark–resight models were lower (0.22–7.92) and had increased precision compared to those from nonspatial capture–recapture (0.50–19.35) and mark–resight techniques (0.54–14.70). Our study is the 1st to estimate the density of a population of carnivores, where only a subset of the individuals are naturally marked, using camera-trapping surveys in combination with spatial mark–resight models. The development of spatial mark–resight and spatially explicit capture–recapture techniques creates the potential for using a single camera-trapping array to estimate the density of multiple, sympatric carnivores, including both partially marked and uniquely marked species.

Los relevamientos con trampas-cámara en combinación con modelos tradicionales o espacialmente explícitos de captura–recaptura, se han convertido en metodologías muy utilizadas para estimar la densidad de carnívoros que pueden ser identificados individualmente. Cuando sólo una porción de la población puede ser identificada inequívocamente, los modelos de marcado–revisualización tradicionales y espacialmente explícitos proveen una alternativa viable. Reanalizamos un conjunto de datos, que se utilizó para estimar la densidad de pumas (Puma concolor) mediante el método fotográfico de captura–recaptura en 3 sitios de estudio en Belice, Argentina y Bolivia, utilizando modelos más novedosos y avanzados incluyendo técnicas de marcado–revisualización tradicionales y espacialmente explicitas. Adicionalmente, evaluamos cómo la identificación de fotografías influyó en las estimaciones de densidad, comparando estimaciones basadas en las historias de captura construidas por 3 investigadores independientes. Estimamos la abundancia de pumas usando modelos de marcado–revisualización en el programa MARK y luego estimamos las densidades ad hoc. También estimamos densidades usando modelos espaciales de marcado–revisualización espacialmente explícitos implementados en un marco Bayesiano. La densidad de pumas no varió sustancialmente entre observadores, pero las estimaciones generadas mediante los 3 modelos estadísticos fueron diferentes. Las densidades de pumas (pumas/100 km²) de modelos de marcado–revisualización espacialmente explícitos fueron más bajas (0.22–7.92) y aumentaron en precisión comparadas con aquellas de captura–recaptura (0.50–19.35) y técnicas de marcado–revisualización no espacialmente explícitos (0.54–14.70). Nuestro estudio es el primero en estimar la densidad mediante la utilización de datos de trampas-cámara en combinación con modelos marcado–revisualización espacialmente explícitos de una población de carnívoros donde sólo un subconjunto de ind

As both companion animals and opportunistic predators, dogs (Canis lupus spp.) have had a long and complex relationship with humans. In Australia, the dingo (C. l. dingo) was introduced 4,000 years ago and, other than humans, is now the continent's top mammalian predator. Domestic dogs (C. l. familiaris) were introduced by Europeans more recently and they interbreed with dingoes. This hybridization has caused growing concern about the roles that domestic dogs and dingoes play in shaping ecosystem processes. There is also considerable debate about whether anthropogenic environmental changes can alter the ecological roles of dingoes. We used scat analysis to test whether the dingo, as the longer-established predator, occupies a different dietary niche from that of free-roaming domestic dogs, irrespective of human influence. Our results demonstrate considerable dietary overlap between dingoes and domestic dogs in areas where humans provide supplementary food, providing evidence against our hypothesis. However, the consumption by dingoes of a greater diversity of prey, in association with historical differences in the interactions between dingoes and humans, suggests a partial separation of their dietary niche from that of domestic dogs. We conclude that anthropogenic changes in resource availability could prevent dingoes from fulfilling their trophic regulatory or pre-European roles. Effective management of human-provided food is therefore required urgently to minimize the potential for subsidized populations of dingoes and domestic dogs to negatively affect co-occurring prey.

Determining habitat associations of small mammal species and environmental characteristics important for site occupancy are central to understanding species biology and community organization. Most studies of small mammal communities are done at a local scale and in 1 habitat, overlooking patterns manifest over a heterogeneous landscape. During the summers of 2009 and 2010 we trapped small mammals throughout Wisconsin at 180 sites among 13 natural habitats, capturing 3,261 individuals of 23 taxa. We modeled site occupancy using habitat characteristics for 16 taxa while incorporating imperfect detection and compared small mammal community similarity among habitats. Site variation in tree density, soil moisture regimes, and winter temperatures were the most important variables in describing occupancy of species. With the exception of Zapus hudsonius and Sorex hoyi, occupancy rates of species were not the same across habitats. Species-specific responses to habitat characteristics created distinct natural habitat associations leading to unique and predictable small mammal assemblages. This study demonstrates the importance of sampling across a wide range of environmental gradients and habitats when determining the distribution of species and how communities are organized at a landscape level.

Mesopredators play an increasingly important role in ecosystems where apex predators have been eliminated, but population ecology of these midsized mammalian carnivores remains poorly understood. We applied Pradel's temporal symmetry models to > 6 years of monthly capture–mark–recapture data and investigated factors influencing apparent survival, recruitment, and realized population growth rate of the Virginia opossum (Didelphis virginiana), an important mesopredator with unique life-history characteristics. Apparent survival did not vary temporally; monthly survival probabilities were 0.86 ± 0.01 (SE) for females and 0.76 ± 0.02 for males. Recruitment rate varied monthly, with the highest recruitment in December (0.32 ± 0.12 for females and 0.57 ± 0.22 for males). Realized population growth rate varied monthly and was also highest in December (1.30 ± 0.17). Both recruitment and population growth rate were positively influenced by the monthly coefficient of variation of precipitation. There was no evidence of density-dependent influences on opossum population dynamics, nor was there evidence of competition from the raccoon (Procyon lotor), a sympatric and abundant mesopredator. Our study is the 1st to simultaneously report survival, recruitment, and population growth rate of Virginia opossums and to investigate factors influencing these rates. In doing so, we provide important insights into the population dynamics of an increasingly influential mesopredator.

Los meso-depredadores juegan un papel cada vez más importante en los ecosistemas donde los depredadores ápice han sido reducidos o eliminados; sin embargo, se conoce poco sobre la ecología poblacional de estos mamíferos carnívoros de tamaño mediano. Nosotros aplicamos modelos simétricos temporales de Pradel a datos mensuales de marcaje, captura y recaptura (de más de 6 años) e investigamos los factores que influencian la sobrevivencia aparente, el reclutamiento y la tasa de crecimiento poblacional de la zarigüeya de Virginia (Didelphis virginiana); el único marsupial que habita al norte de la frontera Mexicana y un importante meso-depredador con características de historia de vida únicas. La sobrevivencia aparente fue diferente entre sexos y no presentó variación temporal, con probabilidades de sobrevivencia mensual de 0.86 ± 0.01 (EE) para hembras y 0.76 ± 0.02 para machos. La tasa de reclutamiento fue diferente entre sexos y varió mensualmente, con un mayor reclutamiento en diciembre (0.32 ± 0.12 para hembras y 0.57 ± 0.22 para machos). La tasa de crecimiento poblacional también varió mensualmente y fue mayor en diciembre (1.30 ± 0.17). Las tasas de reclutamiento y crecimiento poblacional fueron influenciadas positivamente por los coeficientes de variación mensual de la precipitación. No hubo evidencia de un efecto de la densidad sobre la dinámica poblacional de esta zarigüeya, ni evidencia de competencia con el mapache (Procyon lotor), un meso-depredador simpátrico y abundante. Nuestros resultados sugieren que la dinámica poblacional de esta zarigüeya es más fuertemente influenciada por la variación climática que por la competencia inter o intra-específica. Nuestro estudio es el primero en reportar simultáneamente las tasas de sobrevivencia, de reclutamiento y de crecimiento poblacional para la zarigüeya de Virginia, y en investigar los factores que influencian estas tasas con un análisis riguroso de datos de campo tomados sobre un largo periodo tiempo. De esta manera, aportamos información importante sobre la dinámica poblacional de un meso-depredador cada vez más influyente.