Island spotted skunks (Spilogale gracilis amphiala) are a rare subspecies endemic to the California Channel Islands, currently extant on Santa Cruz and Santa Rosa islands. How and when skunks arrived on the islands is unknown, hindering decision-making about their taxonomic status and conservation priority. We investigated these questions by sequencing the complete mitochondrial genomes of 55 skunks from the two islands and mainland (California and Arizona) and examining phylogenetic patterns and estimations of isolation times among populations. Island spotted skunks grouped in a single monophyletic clade distinct from mainland spotted skunks. A haplotype network analysis had the most recent common ancestral haplotype sampled from an individual on Santa Rosa, suggesting both islands were colonized by a single matriline. Additionally, no haplotypes were shared between skunk populations on the two islands. These patterns imply that both island populations were derived from a common ancestral population shortly after establishment and have remained isolated from each other ever since. Together with divergence estimates from three methods, this topology is consistent with colonization of the super-island, Santarosae, by a single ancestral population of spotted skunks in the early Holocene, followed by divergence as the sea level rose and split Santarosae into Santa Cruz and Santa Rosa islands 9,400–9,700 years ago. Such a scenario of colonization could be explained either by rafting or one-time transport by Native Americans. Given their distinct evolutionary history, high levels of endemism, and current population status, island spotted skunks may warrant management as distinct evolutionarily significant units.

For regions that were covered by ice during the Pleistocene glaciations, species must have emigrated from unglaciated regions. However, it can be difficult to discern when and from what ancestral source populations such expansions took place, especially since warming climates introduce the possibility of very recent expansions. For example, in the Great Lakes region, pronounced climatic change includes past glaciations as well as recent, rapid warming. Here we evaluate different expansion hypotheses with a genomic study of the white-footed mouse (Peromyscus leucopus noveboracensis), which is one of the most common mammals throughout the Great Lakes region. Ecological surveys coupled with historical museum records suggest a recent range expansion of P. leucopus associated with the warming climate over the last decades. These detailed records have yet to be complemented by genomic data that provide the requisite resolution for detecting recent expansion, although some mitochondrial DNA (mtDNA) sequences have suggested possible hypotheses about the geography of expansion. With more than 7,000 loci generated using RADseq, we evaluate support for multiple hypotheses of a geographic expansion in the Upper Peninsula of Michigan (UP). Analysis of a single random single-nucleotide polymorphism per locus revealed a fine-scale population structure separating the Lower Peninsula (LP) population from all other populations in the UP. We also detected a genetic structure that reflects an evolutionary history of postglacial colonization from two different origins into the UP, one coming from the LP and one coming from the west. Instead of supporting a climate-driven range expansion, as suggested by field surveys, our results support more ancient postglacial colonization of the UP from two different ancestral sources. With these results, we offer new insights about P. leucopus geographic expansion history, as well as a more general phylogeographic framework for testing range shifts in the Great Lakes region.

Specimens of the Peromyscus boylii species group distributed in the western and northeastern montane regions of Michoacán, México, historically have been assigned to P. levipes. Previous studies indicated that these specimens possessed mitochondrial DNA haplotypes that were distinct from both P. levipes and P. kilpatricki, a recently named species in the P. boylii species group from northeastern Michoacán and western Morelos. Herein karyotypic, DNA sequence, and morphological data were analyzed from those populations to evaluate their taxonomic affinity. Karyotypic data indicated that individuals from western Michoacán (Dos Aguas and Aguililla) and from a newly discovered population in northeastern Michoacán (Zinapécuaro) were chromosomally similar to P. carletoni (FN = 68) but distinct from other taxa assigned to the P. boylii species group. Analyses of cranial characteristics indicated that, relative to other species in the P. boylii species group, two morphologically distinct groups were present that corresponded to the Dos Aguas/Aguililla and Zinapécuaro populations, respectively. The latter population, although represented by a small sample size (n = 5 specimens), appeared to exhibit some trenchant morphological distinctions compared with other cryptic species in the P. boylii group. Phylogenetic analyses (parsimony, Bayesian, and likelihood) of DNA sequences obtained from the mitochondrial cytochrome-b gene indicated that although the individuals from Dos Aguas/Aguililla and Zinapécuaro formed a sister group relationship, they formed monophyletic clades that differed genetically (2.54%)—a level approaching that seen between other sister species of Peromyscus. Further, the Dos Aguas/Aguililla and Zinapécuaro clade was more closely aligned with a clade containing representatives of P. carletoni and P. levipes instead of with those from closer geographic proximities (P. kilpatricki) located in eastern Michoacán. Together, these results indicated that these two populations seemingly represent two undescribed species in the P. boylii species group for which we propose the names Peromyscus greenbaumi for populations in western Michoacán (circa Dos Aguas and Aguililla) and Peromyscus ensinki for populations in northeastern Michoacán (circa Zinapécuaro).

Mice in the diverse genus Peromyscus are emerging as important models in the study of acoustic communication. However, reports on vocal repertoires exist for only 8 of the 56 currently recognized species. Descriptions of acoustic content and context are necessary to facilitate comparative studies. In this study, we present the first recordings of wild-captured pinyon mice (Peromyscus truei) in the laboratory in different social contexts. Similar to other Peromyscus species, pinyon mice produced four general types of vocalizations, including sustained vocalizations (SVs), barks, simple sweeps, and complex sweeps. SVs were produced primarily by females in social isolation, highlighting the potential significance of SVs in female advertisement behavior. While agonistic barks were rare, simple and complex sweeps were reliably produced in response to olfactory cues from same- and opposite-sex mice, and in paired contexts. Opposite-sex pairs produced significantly more complex sweeps than same-sex pairs, consistent with the well-supported function of sweeps in coordinating close-distance interactions. In addition, females produced sweeps with lower peak frequencies following separation from their social partner, indicative of a sex-specific mechanism to facilitate advertisement to potential mates and competitors. Together, our findings highlight the importance of social context in rodent vocal production, the significance of female vocal behavior, and the continued need to sample understudied species to better understand similarities and differences in rodent communication systems.

Los ratones del género politípico Peromyscus están emergiendo como modelos importantes en el estudio de la comunicación acústica. Sin embargo, existen reportes sobre repertorios vocales para solo 8 de las 56 especies actualmente reconocidas. Las descripciones del contenido acústico y el contexto son necesarias para facilitar estudios comparativos. En este estudio, presentamos las primeras grabaciones de ratones piñoneros (Peromyscus truei) realizadas en el laboratorio, en diferentes contextos sociales, y que fueron capturados en terreno. Al igual que otras especies de Peromyscus, los ratones piñoneros produjeron cuatro tipos generales de vocalizaciones que incluyeron vocalizaciones sostenidas (SV), “ladridos”, barridos simples y barridos complejos. Las SVs fueron producidas principalmente por hembras en aislamiento social, lo que destaca la importancia potencial de los SVs en el comportamiento de advertencia de las hembras. Si bien los “ladridos” agonísticos eran raros, los barridos simples y complejos se producían de manera confiable en respuesta a señales olfativas de ratones del mismo sexo y del sexo opuesto, y en contextos emparejados. Los pares de sexos opuestos produjeron barridos significativamente más complejos que los pares del mismo sexo, de acuerdo con la función bien sustentada de los barridos en la coordinación de interacciones a corta distancia. Además, las hembras produjeron barridos con frecuencias máximas más bajas después de la separación de su pareja social, lo cual es indicativo de un mecanismo específico del sexo para facilitar la advertencia a potenciales parejas y competidores. Entonces, nuestros resultados destacan la importancia del contexto social en la producción vocal de los roedores, la importancia del comportamiento vocal de las hembas, y la permanente necesidad de muestrear especies poco estudiadas para comprender mejor las similitudes y diferencias en los sistemas de comunicación de los roedores.

The San Bernardino flying squirrel (Glaucomys oregonensis californicus) is thought to be the southernmost population of the Humboldt's flying squirrel (G. oregonensis) and is restricted to the San Bernardino and San Jacinto Mountains in California. However, recent surveys indicate they have been extirpated from the latter locality. In this study, we characterized the intraspecific genetic structure and diversity of G. oregonensis. We amplified and sequenced at least 300 bp of the mitochondrial cytochrome-b gene and 11 nuclear microsatellites to provide baseline genetic data for this species and subspecies, investigate G. oregonensis genetic structure with a focus on the subspecies distributed in California, and finally evaluate the genetic diversity within G. o. californicus. Population and phylogenetic analyses were performed on a total of 147 samples (tissue, hair, and museum specimen) using the Illumina high-throughput sequencing (HTS) platform, thereby bioinformatically coding microsatellite alleles using established pipelines. Our results indicate reduced genetic diversity in G. o. californicus and highlight genetic distinctiveness of the San Jacinto population. In addition, the differences in genetic diversity between the mitochondrial and nuclear markers suggest sex-biased dispersal and historic separation of the species in multiple refugia followed by more recent gene flow among subpopulations in northern California. This study contributes valuable information toward understanding the genetic variation within G. oregonensis, provides information for future conservation decisions for G. o. californicus, and has novel implications for HTS genotyping-by-sequencing.

Species reintroductions are successful when established populations maintain both demographic stability and genetic diversity. Such a result may be obtained by ensuring both structural habitat connectivity and genetic connectivity among reintroduced and remnant populations. Nevertheless, prezygotic barriers such as assortative mating can prevent the flow of genetic material between populations, even when migration between populations is high. Limited gene flow may be particularly relevant for reintroductions that were sourced either from captive-bred populations or from disparate locations in the wild. American martens (Martes americana) have been reintroduced repeatedly in the Upper Midwestern United States in an effort to establish self-sustaining populations. We quantified levels of genetic diversity within and spatial genetic variance among four marten populations during two time periods separated by 10 years. Spatially informed and naïve discriminant analysis of principal components were used to assign individuals to populations. Results indicate that heterozygosity declined and inbreeding coefficients increased between the two collection periods, while genetic structure among populations also increased. Data are consistent with assortative mating contributing to reapportioning of genetic variation. Population assignment tests show that migration among populations is apparent, but admixture (based on cluster membership probabilities) is low and declined over time. Specifically, martens may be successfully dispersing between populations but a lack of admixture indicates a lack of reproductive contributions to genetic diversity by migrants. Because marten reintroductions in this region are well-documented and well-monitored, lessons can be derived from results to inform future reintroductions. We encourage a careful balance of supplementing genetic diversity via augmentation while avoiding translocation of animals from disparate populations that may result in reproductive isolation of migrants. In combination with the maintenance of a functionally connected landscape, this strategy would maximize the likelihood of a successful reintroduction in terms both of demography and genetics.

Gut microbiomes encode myriad metabolic functions critical to mammalian ecology and evolution. While fresh fecal samples provide an efficient, noninvasive method of sampling gut microbiomes, collecting fresh feces from elusive species is logistically challenging. Nonfresh feces, however, may not accurately represent the gut microbiome of the host due to succession of gut microbial consortia postdefecation as well as colonization by microbes from the surrounding environment. Using American mink (Neovison vison) as a model species, we examined postdefecation microbial community succession to learn how ambient temperature and temporal sampling constraints influence the reliability of nonfresh feces to represent host gut microbiomes. To achieve our goal, we analyzed fresh mink feces (n = 5 females; n = 5 males) collected at the time of defecation from captive mink at a farm in the Upper Peninsula of Michigan and we subsequently subsampled each fecal specimen to investigate microbial community succession over five days, under both warm (21°C) and cold (–17°C to –1°C) temperature treatments. We found that both temperature and time influenced fecal microbiome composition; and we also detected significant sexual dimorphism in microbial community structures, with female mink microbiomes exhibiting significantly greater variation than males' when exposed to the warm temperature treatment. Our results demonstrate that feces from unknown individuals can be a powerful tool for examining carnivore gut microbiomes, though rigorous study design is required because sex, ambient temperature, and time since defecation drive significant microbial variation and the sample size requirements necessary for detecting statistically significant differences between target populations is an important consideration for future ecologically meaningful research.

Climate change is creating hotter, drier, and more extreme weather. Weather anomalies such as extended drought along the Pacific Coast of North America are redefining ecosystems. In the Sierra Nevada mountains of California, an isolated, distinct and federally endangered population of fishers (Pekania pennanti) currently faces multiple threats. Severe drought, tree mortality, and megafires are reshaping the landscape in the southern Sierra with largely unknown effects on fisher ecology and conservation. Using hair collected during long-term population monitoring, we analyzed stable isotopes to quantify the diets of fishers before and after drought, and explored how habitat quality mediated the effect of drought on fisher diet. For the core population of fishers which occupy the northern and western portions of this region, their isotopic niche declined both in drought and in lower-quality habitats. Regardless of drought or habitat conditions, the summer diet of fishers here was dominated by fungi (47%), while little vertebrate mass (14%) was consumed. However, drought and habitat did influence consumption of plants and insects; fishers consumed more insects and less plants in drought conditions and in poorer habitat. In contrast, at the perennially dry, high-altitude Kern Plateau at the southeastern extent of their range, fishers predominantly consumed vertebrates (59%). Fishers show great plasticity in their diet, but the means and capacity for this flexibility is poorly understood. Retaining atypical diet items, notably fungi, and a diversity of forage in the Sierra Nevada could help to buffer the negative fitness costs from rapid environmental change for this endangered species.

The distal gut is home to the dynamic and influential gut microbiome, which is intimately linked to mammalian health by promoting and facilitating countless physiological functions. In a time of increased anthropogenic pressures on wildlife due to widespread habitat destruction, loss of natural prey/foods, and rapid urbanization, the study of wildlife gut microbiomes could prove to be a valuable tool in wildlife management and conservation. Diet is one of the most influential determinants of a host's gut microbiome; yet many wildlife agencies allow baiting to facilitate wildlife harvest, although the impact of human-provisioned foods on wildlife gut health is largely unknown. We used stable isotope analysis derived from carbon (δ¹³C) to index the use of human-provisioned foods by 35 legally harvested American black bears (Ursus americanus), and16S rRNA gene amplicon sequencing to examine the impact of human-provisioned foods on the gut microbial diversity of black bears. We found that greater long-term consumption of human-provisioned foods was associated with significantly reduced microbial species richness and phylogenetic diversity. Our results indicate that consumption of anthropogenic foods through baiting significantly alters the mammalian gut microbiome.

The presence of large carnivores close to people poses unique challenges for wildlife managers working to maintain fully functioning ecosystems while simultaneously minimizing potential risks to public safety and private property. In western North America, cougar (Puma concolor) use of residential areas is relatively commonplace and has contributed to undesirable interactions with people. A common assumption is that cougar population growth translates into greater proximity to people and more interactions, but to our knowledge, direct evaluation of this assumption has not occurred. We used GPS telemetry locations and confirmed cougar–human interaction reports to construct single-sex Leslie matrices, utilization distributions, and a two-stage hurdle model within a Bayesian framework to investigate the effects of population trajectory on cougar use of residential areas and interactions with people in the wildland–urban interface of western Washington. We collected data during two time periods with different expected population growth rates, anticipating greater cougar use of residential areas and interaction levels during the period of increased growth. Contrary to our initial expectations, we did not detect meaningful differences in cougar presence in residential areas or number of interactions with humans between study periods. Instead, we documented consistent space use patterns by all demographic classes that seemed to be governed by different life-history strategies. Interactions with humans were largely a function of individual cougar behaviors during both study periods. The consistent presence of abundant, well-connected wildlands coupled with cougar dispersal likely mitigated the potential effects of population trajectory as the increased expected growth rate in Period 2 manifested primarily as subadult emigration via wildlands. We found that a source population does not necessarily translate into greater proximity to people and more interactions. Cougar management in wildland–urban environments would benefit from the application of strategies that address the complex interplay of biological and anthropogenic factors that contribute to cougar presence in residential areas and their likelihood of interacting with people.

Sleep is important for memory consolidation and maintaining metabolic homeostasis, but sleep can expose animals to inclement weather and predators. Consequently, selection of sleeping sites is important. We tested three sets of hypotheses related to selection of bed sites by female American black bears (Ursus americanus) at two study sites. During 2009–2013, we outfitted 14 female black bears west of Ely, Minnesota, with Global Positioning System collars that reported bear locations every 10 min. We visited 101 bed sites, each identified from clusters of estimated locations where a bear was on site for ≥4 h on two or more occasions, and recorded bed characteristics, forest composition, canopy closure, and ground cover. We matched each bed site with a control site where we collected the same data. During 1987–1991, we outfitted three female black bears south of Ely with very high-frequency transmitter collars and walked with the bears to collect detailed behavioral data. We used the written data records to identify 62 bed sites where bears slept ≥2 h and where bed characteristics were documented. We matched each bed site with a control site approximately 6 h different when the bear was active. Of the bed sites, 132 were used during night and 31 during day. The two study areas differed in the amount of lowland habitats. At both sites, female bears chose bed sites disproportionately in lowland sites with high canopy cover and next to a tree, especially a white pine. Female bears with cubs selected upland bed sites more often than did females without cubs and also more often selected sites adjacent to a tree with coarse bark, which cubs could climb easily. Distances to roads and houses did not affect selection of bed sites by females either with or without cubs.

Ungulates groom to remove ectoparasites but grooming may interfere with foraging, vigilance, and rumination, and it is possible that these effects differ among migratory tactics due to differences in parasite infestations. We compared the effects of grooming for winter ticks (Dermacentor albipictus) on winter foraging behavior by migrating and resident elk (Cervus canadensis) in the partially migratory population at the Ya Ha Tinda, adjacent to Banff National Park, Canada. We used hair loss on the dorsal shoulder area (“withers”) measured from photographic images as an index of tick infestation of individual elk. We conducted 594 focal observations on 48 radio-collared and 18 uncollared individuals that were uniquely identifiable from ear-tags (N = 66) in 2019 to assess whether grooming for ticks in winter reduced time spent foraging, ruminating, or being vigilant. Because rubbing or hair loss from radio-collars may influence tick infestations and behavior, we controlled for whether elk were collared or uncollared in our analyses. Neck hair loss was 3–5% greater in collared elk than uncollared elk, but neither withers hair loss nor time spent grooming differed. Grooming occurred during 42% of the observations but grooming comprised only ∼1% of observation time. Nevertheless, 40% of all grooming was observed during resting, and grooming interrupted vigilance behavior ∼8 times more than foraging. We found no differences among elk following different migratory tactics in time spent grooming or in other behaviors, but one of the two groups of migrant elk had higher withers hair loss. Our results suggest winter ticks may have slight effects on elk relative to other ungulates, particularly moose (Alces alces), in North America.

Habitat disturbance can have negative impacts on biodiversity, such as reducing species richness. The effects of habitat disturbances on parasite infections of host species, potentially altering their survival rate and thus abundance, are less well known. We examined the influence of forest logging in combination with seasonality, host abundance, host body condition, and host sex, on the community composition of gastrointestinal parasites infecting Edward's swamp rat, Malacomys edwardsi. Community composition of parasites did not differ between logged and undisturbed sites, but the abundance of some nematodes (i.e., Ascaris and hookworm) was higher in undisturbed than logged sites. The higher abundance of these nematode species implies a changed host-parasite relationship, thus potentially influencing host persistence.

As fecal steroid methods increasingly are used by researchers to monitor the physiology of captive and wild populations, we need to expand our validation protocols to test the effects of procedural variation and to identify contamination by exogenous sources of steroid hormones. Mammalian carnivore feces often contain large amounts of hair from the prey they consume, which itself may contain high concentrations of hormones. In this study, we report first a validation of two steroid hormone antibodies, corticosterone and progesterone, to determine fecal concentrations of these hormones in wild spotted hyenas (Crocuta crocuta). Next, we expand on these standard validation protocols to test two additional metrics: (i) whether hair from consumed prey or (ii) the specific drying method (oven incubation vs. lyophilization) affect steroid hormone concentrations in feces. In the first biological validation for the progesterone antibody in this species, progesterone concentrations met our expectations: (i) concentrations of plasma and fecal progesterone were lowest in immature females, higher in lactating females, and highest in pregnant females; (ii) across pregnant females, fecal progesterone concentrations were highest during late pregnancy; and (iii) among lactating females, fecal progesterone concentrations were highest after parturition. Our additional validation experiments indicated that contamination with prey hair and drying method are hormone-specific. Although prey hair did not release hormones into samples during storage or extraction for either hormone, its presence appeared to “dilute” progesterone (but not corticosterone) measures indirectly by increasing the dry weight of samples. In addition, fecal progesterone, but not corticosterone, values were lower for lyophilized than for incubated samples. Therefore, in addition to the standard analytical and biological validation steps, additional methodological variables need to be tested whenever we measure fecal hormone concentrations, particularly from predatory mammals.

The identification of bat colonies is essential to conserve and manage these globally threatened mammals. Caves offer potential roosting locations (hibernacula) to hibernating bat species; however, identifying regions where bat-occupied caves exist can be time-consuming. In Texas, caves are often on privately owned land, creating difficulties for accessing and managing potential hibernacula. The tricolored bat (Perimyotis subflavus), a species susceptible to white-nose syndrome, hibernates in caves in the winter in Texas. We sought to identify and quantify site-specific structural and environmental features that influence the presence and abundance of overwintering tricolored bats. We surveyed caves for bats and recorded environmental and structural features of 116 caves January–February 2016, December–February 2016–2017, January–February 2018, and December–February 2018–2019. We used a zero-inflated Poisson regression to identify which features best explained the presence and abundance of tricolored bats. We found that bat presence increased as cave length decreased, and as Normalized Difference Vegetation Index (NDVI) and external vapor pressure deficit increased. Bat abundance increased as number of portals, cave length, NDVI, and external temperature increased. Combining surface data with subsurface features can assist with identifying specific karst regions and known caves within those regions for survey and management efforts.

The Eurasian lynx (Lynx lynx) faces population declines in the western part of its range, and its ecological requirements are poorly understood in the eastern part of its range. The Romanian Carpathians harbor an intact large carnivore community, in which lynx co-occur with bears (Ursus arctos), wolves (Canis lupus), and humans (Homo sapiens), with which they potentially compete for ungulate prey. We provide a science-based estimate of lynx density and habitat use, combining non-invasive monitoring techniques (camera trapping) with spatially explicit capture-recapture models (SECR) in the Southern Carpathians of Romania. We sampled 59 and 76 trap stations during two monitoring sessions (winter and autumn), identified at least 30 individuals, from which we reconstructed encounter histories for 23 individuals. SECR modeling resulted in similar density estimates between winter and autumn (1.6 ± 0.39 SE and 1.7 ± 0.38 SE lynx/100 km², respectively), but the cumulative number of lynx detected reached the asymptote faster during autumn, suggesting that monitoring prior to the mating season is preferable. Density varied within and across sessions with topography (slope), percent forest cover, and landscape heterogeneity (i.e., agricultural mosaic). Density hotspots shifted between low-altitude agricultural mosaic during winter and more rugged, mid-altitude forest stands during autumn. Estimated densities of lynx in the Romanian Carpathians are higher than those reported in the Alps or Slovak Carpathians, highlighting the importance of this population as a source both for natural recolonization and recent reintroduction programs. When used in an SECR framework, camera trapping is an efficient method for assessing spatial and temporal variation in lynx population density in the remote Romanian Carpathians. We recommend this methodology for improving lynx population estimates and to monitor lynx population trends nationwide.

Recent studies have used occupancy models (OM) and ecological niche models (ENM) to provide a better understanding of species' distributions at different scales. One of the main ideas underlying the theoretical foundations of both OM and ENM is that they are positively related to abundance: higher occupancy implies higher density and more suitable areas are likely to have more abundant populations. Here, we analyze the relationship between habitat use measured in terms of occupancy probabilities from OM and environmental suitability derived from ENM in three different Neotropical mammal species: Leopardus wiedii, Cuniculus paca, and Dasypus novemcinctus. For ENM, we used climatic and vegetation cover variables and implemented a model calibration and selection protocol to select the most competitive models. For OM, we used a single-species, single-season model with site covariates for camera-trap data from six different sites throughout the Neotropical realm. Covariates included vegetation percentage, normalized difference vegetation index, normalized difference water index, and elevation. For each site, we fit OM using all possible combinations of variables and selected the most competitive (ΔAICc < 2) to build an average OM. We explored relationships between estimated suitability and occupancy values using Spearman correlation analysis. Relationships between ENM and OM tended to be positive for the three Neotropical mammals, but the strength varied among sites, which could be explained by local factors such as site characteristics and conservation status of areas. We conjecture that ENM are suitable to understand spatial patterns at coarser geographic scales because the concept of the niche is about the species as a whole, whereas OM are more relevant to explain the distribution locally, likely reflecting transient dynamics of populations resulting from many local factors such as community composition and biotic processes.

Limited space on islands usually cannot sustain stable populations of large predators. However, jaguars, the largest cat species in the Americas, unexpectedly occur in the Estação Ecológica Maracá-Jipioca reserve, a system of continental Amazonian islands in the Atlantic Ocean. We investigated jaguar population structure, density, and activity patterns. We placed 25 camera-trap stations across 149.19 km² and used spatially explicit capture–recapture to estimate density, and Rayleigh's test to assess activity patterns. We identified 21 individuals (12 females, six males, and three cubs) and estimated an adult density of 6.7 individuals per 100 km², which equals a population of approximately 43 jaguars. The population is composed mostly of females (66%) in relation to males (33%). Male and female activity patterns overlapped and showed more activity during daytime. The high jaguar density and the presence of females with cubs indicate that these islands are likely natural refugia for jaguars, reinforcing the importance of this protected area for jaguar conservation and possibly challenging the paradigm that large-mammal populations are not feasible in restricted islands.

Mazama temama is the smallest red deer in Central America. It was one of the first species described for the genus, and until the end of the last century many authors considered it as a subspecies of Mazama americana due to morphological similarities. Cytogenetic studies of animals in captivity have shown different karyotypes that led to its recognition as a unique species, and phylogenetic studies sustained the monophyly of the species, with some inconsistencies due to its wide geographical distribution. The objectives of the study were to characterize a topotype of Veracruz and three other specimens from a Campeche locality, to complement the description of M. temama and to propose a neotype for the species. We described this species morphologically (cranial measurements, skin color, and body biometry), and obtained karyorypes from wild animals with known origins for cytogenetic analyses (C band, G band, Ag-NOR, and Giemsa staining). We also performed phylogenetic analyses of Cytb, D-loop, COI, and ND5 mitochondrial genes. The morphometric results separated M. temama from M. americana but not from the other small Mazama species. The phylogenetic trees of mitochondrial genes Cytb, COI, and ND5 corroborated the monophyly of the species with 100% of posterior probability. The topotype's karyotype is significantly different from the one previously described for the species, and the other specimens from Campeche have karyotype variants whose chromosomal rearrangements are possibly the beginning of a reproductive isolation mechanism. We discussed the possibility to have more than one species of red brocket deer in Mexico and Central America.

The coexistence of ecologically similar species is facilitated by differential use of resources along habitat, diet, and/or temporal niche axes. We used feces of non-native rabbit (Oryctolagus cuniculus), hare (Lepus europaeus), goat (Capra hircus), and the native plains viscacha (Lagostomus maximus) to compare the utilization of spatial and trophic resources in an arid ecosystem of Argentina. We expected herbivores to present differential responses in the use of at least one of the niche axes (habitat and/or trophic) associated with seasonal changes in resource availability and according to the origin of the species (native, non-native). We evaluated habitat use and selection through Chi-squared goodness-of-fit tests and Bonferroni confidence intervals, and factors shaping habitat selection (particular components of the habitat type) using generalized linear mixed-effects models. We analyzed the seasonal compositions of diets, breadth of trophic niches, and dietary overlaps. The assemblage of herbivores did not segregate markedly in spatial resource use, showing that hares and goats were more generalist than rabbits and plains viscacha in the utilization of different habitat types. Native and non-native herbivores overlapped markedly in the trophic niche dimension but segregated to some degree in the use of space during wet and dry seasons. The four herbivores shared a similar diet composition. Among dietary items, grasses contributed high percentages during the wet season. Under conditions of resource limitation (dry season), the native plains viscacha differed in feeding strategy from the non-native herbivores. These results deepen our understanding of likely underlying mechanisms that allow coexistence of native and non-native herbivores in an arid ecosystem.

Common hamsters (Cricetus cricetus) are hibernators that rely both on body fat reserves and food stores for the winter period. They face an ongoing population decline in most parts of their distribution and recently were classified as critically endangered. Knowledge on individual body fat proportions in this species is of particular interest for conservation, because it could contribute to better understand the high plasticity in overwintering strategies, overwinter mortality rates, individual variations in reproductive output, and give information on the animals' health state. To calculate body fat proportions, we validated a method that can be applied in the field without the use of anesthesia. To develop this method, we first analyzed the body fat in carcasses of common hamsters using Soxhlet extractions and measured four morphometric parameters (body mass, head length, tibia length, foot length). The morphometric measurements were then integrated in a linear regression model to predict body fat proportions based on the measured values. The morphometric variables yielded an explained variance (adjusted R²) of 96.42% and body fat proportions were predicted with a mean absolute error of 1.27 ± 0.11% from measured values. We applied the model to predict body fat for available field data, which consistently produced reliable values. By measuring the four morphometric parameters and following the provided instructions, body fat proportions can be reliably and noninvasively estimated in captive or free-ranging common hamsters. Furthermore, the method could be applicable to other rodents after species-specific validation.