Journal of Mammalogy最新文献

According to the prey-habitat hypothesis, predatory species may associate with specific habitats that are of high value to their prey; a relationship often overlooked when considering carnivore foraging strategies that can explain how landscape characteristics influence individual fitness. In western North America, western gray (Sciurus griseus) and Douglas's squirrels (Tamiasciurus douglasii) are important prey for fishers (Pekania pennanti), particularly western gray squirrels due to their large body size. Masting trees including Black Oak (Quercus kelloggii) and Tanoak (Notholithocarpus densiflorus) produce an important food source for tree squirrels. Therefore, forest stands containing these trees may be useful to foraging fishers. We hypothesized that: (1) occupancy of a forested stand by western gray and Douglas's squirrels increases with increasing mast production potential of that stand; (2) Fisher stand-use increases with increasing tree squirrel occupancy in that stand; and (3) Fisher stand-use is conditional on only the Western Gray Squirrel occupancy status in that stand. We deployed remote cameras in the northern Sierra Nevada of California in 3 different forest stand types: conifer dominant, conifer co-dominant with tanoak, and conifer co-dominant with Black Oak. We tested the relationships of stand type and other covariates on tree squirrel and Fisher occupancy and detection using single-species occupancy models. We also tested the effect of Western Gray Squirrel presence on Fisher occupancy probability using 2-species co-occurrence models. Douglas's squirrels occupied most sites regardless of stand type. Gray squirrels and fishers had highest rates of occupancy in tanoak co-dominant stands. Fisher stand-use patterns suggested both conditional and unconditional occupancy with western gray squirrels, signifying fishers and gray squirrels may use tanoak stands at high rates irrespective of each other as these stands potentially provide increased access to diverse food resources. Forested stands containing masting trees may support greater numbers of western gray squirrels than other habitats, and retention of this type of tree across the landscape may improve foraging habitat for fishers and other carniovres. Determining which habitat metrics influence prey availability will contribute to understanding carnivore species foraging ecology and inform management and conservation strategies.

Urbanization drives biodiversity loss for many taxa, including arthropods, which serve as the foundation for terrestrial food webs worldwide. Understanding variation in diet among and within wildlife populations across a range of urbanization is especially important for endangered species that often face habitat loss and threats to their prey base. Here, we used molecular metabarcoding of feces to examine geographic and individual variation in the diet of endangered Florida Bonneted Bats, Eumops floridanus, a species whose range is constricted by rapid urban development and whose harem social structure may confer demographic differences in foraging. We used 2 primer sets to amplify insect prey from fecal samples collected from bats in 3 study regions that spanned an urbanization gradient and corresponded to genetically distinct populations. All samples tested contained Lepidoptera, Coleoptera, and Orthoptera-with an especially high diversity of lepidopteran taxa including many large tympanate moths and agricultural pests. In contrast to our predictions, there was no clear influence of urbanization on diet nor marked differences between demographic groups apart from some subtle differences in diet composition and diversity. Instead, our results indicate that distinct populations of E. floridanus preyed on similar insect taxa across their range, with nearly half of identified prey genera being consumed by bats across all 3 regions. Bats from the moderately urban region with the greatest landscape heterogeneity did differ in diet composition and consumed a greater diversity of prey than bats from the urban region, suggesting some influence of landscape composition on foraging. The high overlap in insect prey consumed by E. floridanus across regions suggests that available prey is similar among regions or that the species may select similar resources across the range regardless of availability.

Herbivores are challenged when selecting a diet because many plants have limited nutritional value and some use defenses to avoid being eaten. Understanding diet selection of herbivores in most landscapes also involves choices between native versus nonnative plant species which, in turn, informs management actions to conserve the species. The New England Cottontail, Sylvilagus transitionalis (Bangs 1895)-a species on the decline-is the focus of a large conservation consortium. We conducted microhistological analyses of field collected fecal samples and field surveys of plant species available to determine winter diet of New England cottontails on Patience Island, Rhode Island. Energy density (total nitrogen, crude fat, energy, neutral detergent fiber, acid detergent fiber, ash, and total phenolics) was measured for each of the available plants. A used-available framework was used to determine the selection of each species identified in their feces and how this related to the measured nutritionally relevant constituents. We hypothesized that New England cottontails would select plant species with higher protein and energy values and select native versus nonnative plant species. Unexpectedly, New England cottontails did not select plants with higher protein or energy content but rather plants with higher phenolic and ash levels. In addition, New England cottontails strongly selected native plant species. Our results support previous research that New England cottontails are generalist herbivores, but that plant defenses and whether the plants are native play a role in diet selection.

Human development and lack of habitat can impede spatial population growth for many species. The amount of habitable area available to American black bears has been drastically reduced, especially in the southeastern United States, causing some populations to face possible extirpation. Nonetheless, some Black Bear populations have begun to recover and recolonize portions of historic Black Bear range, despite human-dominated landscapes. The relationship between Black Bear population expansion and human development is especially apparent in Alabama. Our study makes predictions of the potential for population range expansion of black bears in Alabama. We created resource selection models for black bears via a Geographic Information System and location data from GPS-collared black bears. Our models suggested that there are areas of Alabama that could provide opportunities for population growth, allowing bear populations to expand toward their historic distribution. Understanding potential bear population expansion in Alabama could help to inform wildlife managers who are seeking to enhance bear populations and prepare for potential bear population growth in the state and elsewhere in the United States.

Biological invasions pose significant risks to ecosystems and native species. Wild pigs (Sus scrofa) are a highly detrimental invasive species in North America, directly and indirectly affecting native species. Co-occurrence of wild pigs and native species may lead to interspecific interactions that alter ecological communities. Accordingly, we investigated spatial and temporal factors influencing detection and occupancy of Eurasian Wild Pig and Nine-banded Armadillo (Dasypus novemcinctus) before examining interspecific effects. We analyzed camera-trap data collected from August to September 2021 using a hierarchical modeling framework to estimate detection and occupancy of both species individually (single-species analyses) and concurrently (conditional co-occurrence analyses). We observed higher Wild Pig detection rates and space use in late summer and in areas with greater riparian cover, respectively. Armadillo detection increased linearly throughout our sampling season and in response to precipitation. Moreover, armadillo detection was 3.5 to 5.1× higher at sites used by wild pigs, regardless of whether wild pigs were detected during a survey period. Occupancy of armadillo was best explained by a quadratic trend in site elevation but did not depend on the presence of wild pigs. Our results indicate that wild pigs may influence armadillo detection (or site-use intensity), but not occupancy, therefore revealing nuanced interspecific interactions. Between species, we observed high overlap in diel activity but significantly different activity peaks, with armadillos being strictly nocturnal and wild pigs being crepuscular but with more cathemeral activity, suggesting that fine-scale temporal partitioning may have occurred. Our results provide insights into the influence of a large-bodied and destructive invasive species (Wild Pig) on a smaller, ecologically important native species (Nine-banded Armadillo).

American pikas (Ochotona princeps) are small, thermally sensitive mammals that primarily live in montane and alpine environments. The Sierra Nevada lineage (O. p. schisticeps) has experienced numerous local extinctions, most of which occurred in hotter, drier regions such as the Great Basin. Few genetic studies have assessed these at-risk populations. This study aims to fill that gap by conducting fine-scale genetic analyses on populations in low-elevation Great Basin habitat in northwestern Nevada. Specifically, we: (i) quantified genetic diversity and structure among populations within O. p schisticeps, with particular focus on northwestern Nevada; and (ii) assessed the influence of primary productivity and climate-related variables on genetic diversity within O. p schisticeps, as well as at the broader species level. Great Basin populations exhibited the lowest levels of genetic diversity. Within O. p. schisticeps, population genetic diversity was positively correlated with annual precipitation-while at the species level temperature explained the most variation in genetic diversity. These results provide insight into climate-driven range contractions predicted for this species and inform conservation and management decisions.

Scaptonyx fusicauda Milne-Edwards, 1872, is a mole species and a burrowing animal occurring from central China to northeastern Myanmar and northern Vietnam. This is the only extant species currently known in the genus Scaptonyx (Talpidae), but recent studies have revealed highly diverse lineages within this taxon. However, the broken type specimen and unspecified type locality of this species have hindered comparison between specimens towards a taxonomic evaluation. We reviewed the literature documenting the expeditions of the collector Armand David and narrowed down the type locality of this species to Minshan Mountain, western Sichuan, China. We compared S. fusicauda topotypes with specimens from 2 separated mountain ranges in western Yunnan, China-S. f. affinis Thomas, 1912 from the Baima Mountain and an undescribed species (S. sp. 1) from the Gaoligong Mountains. Specimens from the 3 localities can be distinguished by multiple external, craniomandibular, and dental characteristics. Phylogenies based on mitochondrial and nuclear genes also provided consistent topologies supporting S. fusicauda, S. f. affinis, and S. sp. 1 as distinct monophyletic species. Scaptonyx sp. 1 split from the sister clade (S. fusicauda + S. f. affinis) ca. 19.79 Ma, while S. f. affinis split from S. fusicauda ca. 9.56 Ma. Following these findings, we recognize S. f. affinis as a distinct species, S. affinis, and describe S. sp. 1 as a new species. Scaptonyx fusicauda occurs in the Sichuan Basin to the west, S. affinis from the mountains in the east of the Salween River to central China and northern Vietnam, and S. sp. 1 in the Gaoligong Mountains on the watersheds of the Irrawaddy and Salween rivers-encompassing western Yunnan, China, and northeastern Myanmar.

Reliable population size estimates are imperative for effective conservation and management, but are notoriously difficult to obtain for rare, cryptic species such as large carnivores. Genetic capture-mark-recapture (CMR) models can provide robust population size estimates and may be conducted noninvasively during a single sampling period. African leopards (Panthera pardus) are listed as vulnerable, with declining populations. However, population size estimates are rare for much of their range. Here, we provide population size estimates for leopards in the Limpopo (LNP) and Banhine (BNP) national parks and the Lebombo Conservancy (LC), in western Mozambique. We estimate population sizes using SNP-based CMR models derived from genetic information acquired noninvasively from scats collected across the sites. Additionally, we compare our density estimates with those derived from trophic scaling to provide inferences on the drivers of Leopard density in the region. We estimate populations of 87, 15, and 13 leopards in LNP, BNP, and LC, respectively. Population size estimates derived from trophic scaling suggest that leopards are limited by bottom-up prey resources in LNP and LC, but there is evidence for top-down regulation in BNP. Given the precariousness of Leopard populations in the region, we urge use of population monitoring using genetic CMR models to inform conservation and management.

The ability to reliably differentiate age cohorts and detect and quantify sexual dimorphism in wildlife species is crucial before performing many ecological and biological analyses, including population demographics and commonly used body condition indices. In many wildlife species, however, these analyses are limited by a lack of detailed and reliable data. We used a long-term data set (>30 years and >2,600 individuals) to establish a method to reliably differentiate juvenile, subadult, and adult southern hairy-nosed wombats (Lasiorhinus latifrons) and provide evidence of sexual dimorphism in this species. Adult and subadult males were separated primarily through measurements of head width and head length, based on measurements from confirmed adult males (n = 160). We found adult males to have significantly longer (P-value = 4.374e^-16) and wider (P-value = 2.2e^-16) heads than adult females and a significantly longer pes length (P-value = < 2.2e^-16). This divergence appears to occur when subadult males are approaching adulthood. However, no difference in body weight or total body length was observed between the sexes. Using these data, we established approximate size ranges for wombats of all age cohorts to underpin future research on the impacts of rainfall and drought on body condition, breeding, recruitment, and survival in this semiarid dwelling species. This research also highlights the importance of separating the sexes for analyses involving body measurements even when the species does not display obvious dimorphism.

[This corrects the article DOI: 10.1093/jmammal/gyae133.].