Global change imposes multiple challenges on species and, thus, a reliable prediction of current and future vulnerability of species must consider multiple stressors and intrinsic traits of species. Climate, physiology, and forest cover, for example, are required to evaluate threat to thermolabile forest-dependent species, such as sloths (Bradypus spp.; Mammalia: Xenarthra). Here, we estimated future changes in the distribution of three sloth species using a metabolic-hybrid model focused on climate (climatic only, i.e., CO approach) and adding forest cover constraints to distribution of species (climate plus land cover, i.e., CL approach). We used an innovative method to generate estimates of physiological parameters for endotherms, validated with field data. The CF approach predicted a future net expansion of distribution of B. torquatus and B. variegatus, and a future net contraction of distribution of B. tridactylus. The inclusion of forest cover constraints, however, reversed the predictions for B. torquatus, with a predicted net distribution contraction. It also reduced expansion of B. variegatus, although still showing a large net expansion. Thus, B. variegatus is not predicted to be threatened in the future; B. tridactylus emerges as the species most vulnerable to climate change, but with no considerable forest losses, while B. torquatus shows the opposite pattern. Our study highlights the importance of incorporating multiple stressors in predictive models in general. To increase resilience of species to climate change, it is key to control deforestation in the Amazon for B. tridactylus, and to promote reforestation in the Atlantic Forest for B. torquatus.

As mudanças globais impõem vários desafios à biodiversidade e uma previsão confiável da vulnerabilidade atual e futura das espécies deve considerar vários estressores e características intrínsecas das mesmas. Clima, fisiologia e cobertura florestal, por exemplo, são necessários para avaliar a ameaça às espécies dependentes da floresta e termolábeis, como as preguiças (Bradypus spp.; Mammalia: Xenarthra). Aqui, estimamos as mudanças futuras na distribuição de três espécies de preguiças usando um modelo híbrido metabólico focado no clima (abordagem apenas climática, CO) e adicionando restrições de cobertura florestal à distribuição das espécies (abordagem de clima mais cobertura florestal, CL). Utilizamos um método inovador para gerar estimativas de parâmetros fisiológicos para endotérmicos, validado com dados de campo. A abordagem CO previu uma expansão líquida futura da distribuição de B. torquatus e B. variegatus, e uma contração líquida futura da distribuição de B. tridactylus. A inclusão de restrições de cobertura florestal, no entanto, reverteu as previsões de B. torquatus, com uma contração da distribuição líquida prevista. A restrição de cobertura florestal também reduziu a expansão de B. variegatus, embora ainda exiba uma grande expansão líquida. Assim, B. variegatus não está previsto para ser ameaçado no futuro; B. tridactylus emerge como a espécie mais vulnerável às mudanças climáticas, mas sem perdas florestais consideráveis, enquanto B. torquatus mostra o padrão oposto. Nosso estudo destaca a importância de incorporar múltiplos estressores em modelos preditivos em geral. Para aumentar a resiliência das espécies às mudanças climáticas, é fundamental controlar o desmatamento na Amazônia para B. tridactylus e promover o reflorestamento na Mata Atlântica para B. torquatus.

While museum voucher specimens continue to be the standard for species identifications, biodiversity data are increasingly represented by photographic records from camera traps and amateur naturalists. Some species are easily recognized in these pictures, others are impossible to distinguish. Here we quantify the extent to which 335 terrestrial nonvolant North American mammals can be identified in typical photographs, with and without considering species range maps. We evaluated all pairwise comparisons of species and judged, based on professional opinion, whether they are visually distinguishable in typical pictures from camera traps or the iNaturalist crowdsourced platform on a 4-point scale: (1) always, (2) usually, (3) rarely, or (4) never. Most (96.5%) of the 55,944 pairwise comparisons were ranked as always or usually distinguishable in a photograph, leaving exactly 2,000 pairs of species that can rarely or never be distinguished from typical pictures, primarily within clades such as shrews and small-bodied rodents. Accounting for a species geographic range eliminates many problematic comparisons, such that the average number of difficult or impossible-to-distinguish species pairs from any location was 7.3 when considering all species, or 0.37 when considering only those typically surveyed with camera traps. The greatest diversity of difficult-to-distinguish species was in Arizona and New Mexico, with 57 difficult pairs of species, suggesting the problem scales with overall species diversity. Our results show which species are most readily differentiated by photographic data and which taxa should be identified only to higher taxonomic levels (e.g., genus). Our results are relevant to ecologists, as well as those using artificial intelligence to identify species in photographs, but also serve as a reminder that continued study of mammals through museum vouchers is critical since it is the only way to accurately identify many smaller species, provides a wealth of data unattainable from photographs, and constrains photographic records via accurate range maps. Ongoing specimen voucher collection, in addition to photographs, will become even more important as species ranges change, and photographic evidence alone will not be sufficient to document these dynamics for many species.

Biologists have long pondered the extreme limits of life on Earth, including the maximum elevation at which species can live and reproduce. Here we review evidence of a self-sustaining population of mice at an elevation that exceeds that of all previously reported for mammals. Five expeditions over 10 years to Volcán Llullaillaco on the Argentina/Chile border observed and collected mice at elevations ranging from 5,070 m at the mountain's base to the summit at 6,739 m (22,110 feet). Previously unreported evidence includes observations and photographs of live animals and mummified remains, environmental DNA, and a soil microbial community reflecting animal activity that are evaluated in combination with previously reported video recordings and capture of live mice. All of the evidence identifies the mouse as the leaf-eared mouse Phyllotis vaccarum, and it robustly places the population within a haplotype group containing individuals from the Chilean Atacama Desert and nearby regions of Argentina. A critical review of the literature affirms that this population is not only an elevational record for mammals but for all terrestrial vertebrates to date, and we further find that many extreme elevations previously reported for mammals are based on scant or dubious evidence.

Durante mucho tiempo los biólogos han reflexionado sobre los límites extremos de altura a la que las especies pueden vivir y reproducirse. Aquí presentamos nueva evidencia sobre la existencia de una población de ratones establecida a una elevación que supera todos los reports previos para mamíferos. Durante 10 años fueron realizadas 5 expediciones al Volcán Llullaillaco, ubicado en la frontera entre Argentina y Chile; observando y colectando ratones en elevaciones que van desde los 5,070 m hasta la cima de 6,739 m (22,110 feet). La nueva evidencia incluye fotografías de restos momificados, ADN ambiental y la actividad microbiana del suelo que confirman la presencia del animal, la cual fue analizada junto a videos reportados anteriormente y la captura de ejemplares vivos. Toda esta información indica que dicha población corresponde al ratón orejudo amarillento Phyllotis vaccarum y lo posicionan dentro de un grupo de haplotipos compuesto por individuos del Desierto de Atacama y regiones cercanas en Argentina. La revisión crítica de la literatura demostró que esta población no solo es un récord de elevación para los mamíferos, sino para todos los vertebrados terrestres; igualmente, que los reportes de elevaciones extremas reportados para mamíferos se derivan de evidencias escasas y dudosas.

Distress vocalizations are emitted by animals experiencing extreme physical distress, such as when caught by a predator. These signals are emitted by numerous and phylogenetically distant vertebrate species and are composed of sequences of broadband and high-amplitude notes. In this study, we provide the first acoustic characterization of distress vocalizations in four armadillo species: pink fairy armadillo (Chlamyphorus truncatus), greater fairy armadillo (Calyptophractus retusus), Southern three-banded armadillo (Tolypeutes matacus), and Chacoan naked-tailed armadillo (Cabassous chacoensis). We also recharacterized the weeping call of the screaming hairy armadillo (Chaetophractus vellerosus) to compare vocalizations, discuss potential homologies, and examine possible causes of structural and acoustic similarities among these species. In three species the vocalizations were sequences of exhaled notes that differed in their fine spectral structure (exhaled harmonic notes in C. retusus, and exhaled harsh notes in C. truncatus and T. matacus). The vocalization of C. chacoensis was composed of exhaled harsh and inhaled harsh notes that occurred alternately and continuously in a quick sequence. Based on the mode of production and acoustic similarity, we propose that the notes of C. retusus and C. truncatus would be homologous to the conspicuous crying notes of C. vellerosus. The exhaled harsh notes of T. matacus and C. chacoensis may also be homologous to the crying notes of C. vellerosus, but the notes of T. matacus are quite different in various acoustic parameters. Furthermore, the inhaled and exhaled harsh notes of C. chacoensis are similar to the inhaled and exhaled sobbing notes of C. vellerosus, making assessments of homologies uncertain in these species. Because a common motivational state (physical distress) underlies these vocalizations, we propose that the notable differences in body size and habitat preferences of the armadillos could represent potential drivers of the acoustic divergence among their vocalizations.

Las vocalizaciones de pánico son emitidas por individuos cuando experimentan estrés físico, como ser capturados por un depredador. Estas señales están compuestas por secuencias de notas de banda ancha y alta amplitud, y son producidas por numerosas especies de vertebrados filogenéticamente distantes. En este estudio, caracterizamos las vocalizaciones de pánico de cuatro especies de armadillo: pichiciego menor (Chlamyphorus truncatus), pichiciego chaqueño (Calyptophractus retusus), armadillo de tres bandas (Tolypeutes matacus) y cabasú chaqueño (Cabassous chacoensis). Para comparar vocalizaciones, discutir homologías y examinar posibles causas de las similitudes acústicas entre armadillos, re-caracterizamos la vocalización de pánico del piche llorón (Chaetophractus vellerosus). En tres especies, la vocalización estuvo compuesta por secuencias de notas exhaladas que difirieron en su estructura espectral (notas armónicas exhaladas en C. retusus y notas ásperas exhaladas en C. truncatus y T. matacus). La vocalización de C. chacoensis estuvo compuesta por notas ásperas exhaladas y ásperas inhaladas emitidas de forma alterna y continua en una secuencia rápida. Considerando el modo de producción y la similitud acústica, proponemos que las notas de C. retusus y C. truncatus serían homólogas a las notas lloradas de C. vellerosus. Las notas ásperas exhaladas de T. matacus y C. chacoensis también podrían ser homólogas a las notas lloradas, sin embargo, las notas de T. matacus difieren en su estructura acústica. Además, las notas ásperas inhaladas y exhaladas de C. chacoensis son similares a las notas sollozas inhaladas y exhaladas de C. vellerosus, lo que hace inciertas las homologías entre estas especies. Debido a que el estado motivacional (angustía física) subyacente a la emisión de estas vocalizaciones es equivalente entre las especies, proponemos que las diferencias en el tamaño corporal y las preferencias de hábitat de las especies podrían representar los impulsores potenciales de la divergencia acústica entre sus vocalizaciones.

The Natal long-fingered bat, Miniopterus natalensis, is an insectivorous, regional migrating species that exhibits sex-specific migration patterns. We explored the variability of isotopic niches using δ¹³C and δ¹⁵N ratios in fur from female and male bats in different reproductive states: pregnant, reproductive (but not pregnant at the time of this study), and nonreproductive females; nonscrotal and scrotal males using Bayesian standard ellipse areas and generalized linear models. Reproductive status was an informative predictor for the observed variation of both δ¹³C and δ¹⁵N ratios. Pregnant females displayed the highest mean δ¹³C and δ¹⁵N ratios and were distinct from other reproductive states. Reproductive females exhibited significantly higher δ¹⁵N ratios than nonreproductive females or nonscrotal and scrotal males, which may reflect state-dependent foraging and/or higher metabolic stress. Scrotal males displayed the lowest mean δ¹³C and δ¹⁵N ratios. Nonscrotal males exhibited the broadest isotopic niche, whereas reproductive females had the narrowest isotopic niche. Differences in isotopic niche sizes between the different reproductive groups may relate to variable individual feeding behavior and/or geographically different foraging areas/migratory stopover sites at individual and intraspecific levels in M. natalensis. This suggests that group-living, cave-dwelling bats may employ individual foraging specialization to facilitate coexistence in the broader geographic landscape.

The spread of white-nose syndrome into western North America has caused concerns that bat species inhabiting the region will soon experience population declines like those seen to the east. However, much of the region lacks baseline estimates of abundance for bats believed to be susceptible to WNS due to a scarcity of known hibernacula, where populations are traditionally monitored. The goal of this study was to determine the abundance, roost fidelity, and activity patterns of summer colonies of female little brown myotis (Myotis lucifugus) in an area with no known hibernacula. To accomplish this, we subcutaneously implanted passive integrated transponder (PIT) tags into 297 female little brown myotis from 2015 to 2018 and installed radio-frequency identification (RFID) readers and antennas inside three maternity roosts in Yellowstone National Park. Bats occupied RFID-monitored roosts on 32% of days and were never detected at maternity roosts located > 16 km from where they were tagged. Roost fidelity varied throughout summer and was greatest during late gestation and early lactation. This allowed us to combine nightly scans of RFID-tagged bats with visual emergence counts to estimate the population of bats using two roosts located >16 km apart during 2017–2018. Population estimates of both colonies were markedly higher (N* = 208 ± 6 bats and N* = 836 ± 67 bats during 2018) than the number of bats seen during evening emergence (high counts of 127 and 222, respectively). Nocturnal visits of tagged bats to these roosts increased around the time of parturition, indicative of bats returning to nurse young. These data show that emergence count and PIT tag data can be combined to monitor bat population abundance and activity patterns in areas where hibernacula are absent or where their locations are unknown.

Knowledge of habitat suitability (HS) is required for effective conservation planning, yet it can be difficult to obtain. In the absence of local HS information, managers often use studies from other areas to guide their decisions, typically without local validation. We tested the hypothesis that HS is consistent across a species range, and thus reliably extrapolated to understudied sites. We focused on the puma, Puma concolor, a widely distributed large carnivore of conservation and management importance. We conducted a meta-analysis of 41 studies to calculate a mean effect size for six of the most common predictor variables used in mammal HS research. Using the estimated effect sizes in a regression model which included all six variables, we created a new HS model for pumas in an understudied site, the Tumbesian Region (TR). We contrasted predictions from this range-wide model with those from three more regionally specific HS models: a model developed in the Caatinga, Brazil (Caatinga model), a model considering only tropical studies (tropical model), and a model using only studies from the United States and Canada (temperate model). We used puma detection rates from camera trap surveys across the TR to validate model predictions. Although mean effect sizes of habitat predictor variables varied across puma range, all models provided useful predictions of HS for pumas in the TR (area under the receiver operating characteristic curve [AUC] > 0.64). Unexpectedly, the temperate model was best at predicting puma HS in the TR (AUC: 0.77; r_s = 0.3), followed by the range-wide model (AUC = 0.73; r_s = 0.29). The tropical and Caatinga models had lower predictive accuracy (AUC = 0.68; r_s = 0.28 and AUC = 0.64; r_s = 0.23, respectively). The accuracy of the tropical model improved when the area of potential recent puma extirpation was excluded from the validation data set. These results highlight that although HS for P. concolor varies across the species range, information collected across a wide range of sites may be better than only locally or regionally specific information for informing HS in understudied sites (e.g., for habitat protection, restoration areas). Given the pressing need for actions to address widespread biodiversity declines, existing knowledge can be used to predict HS to data-poor regions and inform conservation planning while also motivating model validations and targeted data collection.

Para planificar estrategias de conservación efectivas, se requieren conocimientos sobre la idoneidad del hábitat (IH); sin embargo, esto suele ser difícil de obtener. En ausencia de información local de IH, los tomadores de decisiones a menudo usan estudios de otras áreas para guiar sus decisiones, generalmente sin validación local. Probamos la hipótesis de que la IH es consistente en todo el rango de distribución de las especies y, por lo tanto, puede ser extrapolada de manera confiable a sitios poco estudiados. Nuestra especie de estudio fue el puma, Puma concolor, un carnívoro ampliamente distribuido y de importancia para la conservación y el manejo. Realizamos un meta-análisis de 41 estudios para calcular el tamaño del efecto promedio para seis de las variables predictoras más utilizadas en la investigación de IH en mamíferos. Utilizamos los tamaños de efecto estimados en un modelo de regresión que incluyó las seis variables y luegom extrapolamos este modelo a un sitio poco estudiado, la región Tumbesina (TR). Comparamos las predicciones del modelo global con las de otros tres modelos regionales: un modelo de la Caatinga en Brasil (Caatinga model), un modelo considerando solo las investigaciones en el trópico (tropical model) y un modelo utilizando únicamente las investigaciones de EE.UU. y Canadá (temperate model). Para validar las predicciones de los modelos, utilizamos las tasas de detección de pumas obtenidas de muestreos con cámaras trampa distribuidos en la TR. A pesar de que los tamaños del efecto promedio por variable variaron a lo largo de la distribución de los pumas, todos los modelos predijeron la IH mejor que un modelo aleatorio (AUC > 0.64). El temperate model fue el mejor modelo de IH en la TR (AUC: 0.77; r_s = 0.3), seguido del modelo general (range-wide model) (AUC = 0.73; r_s = 0.29). El modelo tropical y Caatinga tuvieron una precisión predictiva baja (AUC = 0.68; r_s = 0.28 & AUC = 0.64; r_s = 0.23, respectivamente). La precisión predictiva del model tropical se incrementó cuando se excluyeron de la validación a las localidades que representan la posible extinción local de puma. Estos resultados destacan que a pesar que la IH para Puma concolor es variable a lo largo de su distribución, la información recopilada a lo largo de su distribución puede ser mejor que solo la información local o específica para informar la IH en sitios poco estudiados. Dada la urgente necesidad de acciones para abordar la disminución generalizada de la biodiversidad, el conocimiento existente se puede utilizar para predecir la IH en regiones con pocos datos e informar la planificación de la conservación, al mismo tiempo que motiva la validación de modelos y la recopilación de datos específicos.

Insectivorous bats are particularly susceptible to heat loss due to their relatively large surface area to volume ratio. Therefore, to maintain a high normothermic body temperature, bats require large amounts of energy for thermoregulation. This can be energetically challenging for small bats during cold periods as heat loss is augmented and insect prey is reduced. To conserve energy many bats enter a state of torpor characterized by a controlled reduction of metabolism and body temperature in combination with selecting roosts based upon thermal properties. Our study aimed to quantify torpor patterns and roost preferences of free-ranging little forest bats (Vespadelus vulturnus) during winter to identify physiological and behavioral mechanisms used by this species for survival of the cold season. All bats captured were male (body mass 4.9 ± 0.7 g, n = 6) and used torpor on every day monitored, with bouts lasting up to 187.58 h (mean = 35.5 ± 36.7 h, n = 6, total number of samples [N] = 61). Torpor bout duration was significantly correlated with daily minimum and maximum ambient temperature, mean skin temperature, insect mass, and body mass of individuals and the multiday torpor bouts recorded in the cold qualify as hibernation. The lowest skin temperature recorded was 5.2°C, which corresponded to the lowest ambient temperature measurement of –5.8°C. Most bats chose tall, large, live Eucalyptus trees for roosting and to leave their roost for foraging on warmer days. Many individuals often switched roosts (every 3–5 days) and movements increased as spring approached (every 1–2 days). Our data suggest that V. vulturnus are capable of using the environmental temperature to gauge potential foraging opportunities and as a cue to reenter torpor when conditions are unsuitable. Importantly, frequent use of torpor and appropriate roost selection form key roles in the winter survival of these tiny bats.

In 1995, eight female pumas from Texas (Puma concolor stanleyana) were introduced into five areas in South Florida to remediate morphological and biomedical correlates of inbreeding depression that threatened the long-term survival of Florida panthers (P. c. coryi). Initial analysis of the results of this genetic introgression initiative has highlighted its success, including growth of the population, increased genetic heterozygosity, and reduced frequencies of physical traits associated with inbreeding, including cryptorchidism. However, panthers remain isolated from other puma populations and natural gene flow is not currently plausible. Using data collected from 65 panthers in the post-genetic introgression era (1998–2020), we assessed the benefits accrued to male panther reproductive parameters via this management initiative, the effect of genetic variables, and compared results to historic data. Microsatellite data were used to determine individual heterozygosity levels and qualify panther genetic ancestry as admixed (i.e., panthers descended from crosses with female Texas puma) or canonical (i.e., panthers that comprised most of the population prior to genetic introgression). A total of 47 admixed and 10 canonical panthers were identified; mean individual heterozygosity of canonical panthers (0.39) was significantly different from admixed panthers (0.63; t₅₄ = 4.7, P-value < 0.001). Admixed panthers exhibited higher mean values for total testicular volume, structurally normal spermatozoa, and total sperm in comparison to canonical panthers. The progressive improvement of sperm metrics demonstrates that the benefits of genetic introgression continue to have a positive impact on the population >25 years since the release of the Texas pumas. However, the Florida panther population remains small, isolated, and vulnerable to deterministic and stochastic events that warrants continued monitoring to assess when additional genetic introgression initiatives will need to be implemented in the future.

Recognizing individual variation in body growth characteristics and size at sexual maturity is of particular interest because they indicate a potential source of variance in survival and reproductive fitness. I used the Richards group of unified models method to examine body growth characteristics, mass at sexual maturity, and development of sexual size dimorphism in Florida panthers (Puma concolor coryi). A larger asymptotic body size and mass at sexual maturity in males resulted from a greater instantaneous growth rate across the life span and longer duration of growth than in females. Juvenile males attained larger body mass than female counterparts before achieving independence and sexual maturity, suggesting that a greater instantaneous growth rate developed from precopulatory intrasexual selection. Body mass growth rapidly decreased proximate to the minimum age at first conception in both sexes, suggesting that energetic costs of reproduction inhibited additional growth. Intrasexual selection among males to enhance fighting ability and promote access to a territory and mates is implicated as the cause for sexual size dimorphism, together with more direct underlying energetic costs of reproduction in females. The results provide uniform sex-specific body mass-at-age growth and mass at sexual maturity statistics for comparison with other puma populations and reference values to implement measurable criteria to evaluate trends in Florida panther population health.

Reconocer la variación individual en las características de crecimiento corporal y tamaño en la madurez sexual es de particular interés porque indican una fuente potencial de variación en la supervivencia y capacidad reproductiva. Aquí, utilizo el método de modelos unificados de Richard para examinar las características de crecimiento corporal, la masa en la madurez sexual y el desarrollo del dimorfismo del tamaño sexual en las panteras de Florida (Puma concolor coryi). Un mayor tamaño corporal y masa asintóticas en la madurez sexual en los machos resultó de una mayor tasa de crecimiento instantáneo a lo largo de la vida y una mayor duración del crecimiento que en las hembras. Los machos jóvenes alcanzaron una masa corporal mayor que las hembras antes de alcanzar la independencia y la madurez sexual, lo que sugiere que una mayor tasa de crecimiento instantáneo se desarrolló a partir de la selección intrasexual precopulatoria. El crecimiento de la masa corporal disminuyó rápidamente cerca de la edad mínima en la primera concepción en ambos sexos, lo que sugiere que los costos energéticos de la reproducción inhibieron el crecimiento adicional. La selección intrasexual entre los machos para mejorar la capacidad de lucha y promover el acceso a un territorio y a las parejas es sugerida como la causa del dimorfismo sexual en el tamaño, junto con los costos energéticos subyacentes más directos de la reproducción en las hembras. Los resultados proporcionan estadísticas de crecimiento de masa corporal por edad y masa corporal a la madurez sexual para su comparación con otras poblaciones de pumas, y valores de referencia para implementar criterios medibles para evaluar las tendencias en la salud de la población de panteras de Florida.

Movement patterns of lions (Panthera leo) reveal how they hunt large herbivores in heterogeneous landscapes such as the Kruger National Park in South Africa. Large herbivores are distributed differently on the landscape and therefore have different vulnerabilities as prey for lions. For instance, blue wildebeest (Connochaetes taurinus) occupy small grazing lawns at night but are difficult for lions to capture because open areas lack cover for stalking. African buffalo (Syncerus caffer) aggregate in large herds but are less available because these herds only intermittently enter the home ranges of individual lion prides. Unlike large herds of wildebeest and buffalo, plains zebra (Equus quagga) move widely in small herds while browsing greater kudus (Tragelaphus strepsiceros) and giraffes (Giraffa camelopardalis giraffa) generally occur in lower densities. We used spatial data derived from GPS collars to investigate several hypotheses regarding the movements of three lion prides in response to their prey. We found that lions were most active and moved longer distances during nighttime than during daytime. Lions remained within their core home ranges on 87% of nights and wandered to the outlying areas of the home ranges every second night. Lions visited grazing lawns, that is, area of short grass, where wildebeest herds resided every second night, and moved toward the direction of buffalo herds within 2 km of vicinity. Lions spent more time near riverbanks that provided dense woody cover at night than expected but concentrated only weakly near sites with surface water where herbivores drank in the dry season. Our study contributes to understanding how lions vary their movements in response to the spatial and temporal heterogeneity in the relative availability and vulnerability of multiple prey species.

Twenty-three species and four subspecies of odontocete belonging to five families (Delphinidae, Physeteridae, Kogiidae, Phocoenidae, and Ziphiidae) are distributed along the Pacific coast of northern Mexico. The morphological variability of these species has been studied extensively and a number of taxonomic studies have focused on cranial characteristics. The goal of this study was to describe the periotics of the odontocetes of the Pacific coast of northern Mexico and develop a taxonomic tool using descriptions of each species. We used a geometric morphometric analysis of 186 periotics housed in local and national osteological collections. Our results show the taxonomic value of periotics and a significant phylogenetic signal associated with this structure. Based on these results we present a descriptive catalog that can be used for identification purposes.

En la costa noroeste del Pacífico mexicano, se distribuyen 23 especies y cuatro subespecies de odontocetos pertenecientes a cinco familias (Delphinidae, Physeteridae, Kogiidae, Phocoenidae y Ziphiidae). La alta variabilidad morfológica de estas especies ha sido objeto de diversas investigaciones, varias de las cuales se han centrado en aspectos taxonómicos basados en características craneales. El objetivo de este estudio fue describir los perióticos de los odontocetos de la costa noroeste del Pacífico mexicano y elaborar una herramienta taxonómica a través de la descripción de cada especie. Se realizó un análisis de morfometría geométrica empleando 186 perióticos depositados en colecciones osteológicas locales y nacionales. Nuestros resultados enfocados en 17 especies, indicaron que los perióticos son estructuras que presentan valor taxonómico y señal filogenética. Con base en los resultados morfométricos y las observaciones directas, preparamos un catálogo que describe los perióticos de cada especie, el cual se podrá emplear como una herramienta útil para fines de identificación.

The skull often reveals adaptation to ecological and environmental influences. Food availability affects the somatic growth of otariids, and population abundance can influence male intrasexual competition. We hypothesized there would be regional differences between Galapagos sea lion (GSL, Zalophus wollebaeki) rookeries as a result of variance in ecosystem metrics and population abundance. We used skull measures related to individual size and aggressiveness. We analyzed 19 linear measures for size and 15 for aggressiveness taken on 49 adult male skulls of GSL collected in four bioregions of the archipelago. Nine skull measures had a significant effect on individual clustering into bioregions (P < 0.001). The most discriminating measures were snout length, supraorbital process width, nasal length, and canine width. We found a significant relationship between skull grouping patterns and chlorophyll-α levels (proxy marine productivity and body growth) and GSL population abundance (proxy of agonistic behavior) of each bioregion, as well as with the interaction between both variables (P < 0.001). Our results suggest significant regional differences in GSL skull morphometry, which could be associated with resource availability and level of male intrasexual competition in the archipelago. This information is important for understanding the life history of this species.

El cráneo es útil para mostrar los efectos de adaptación de las especies a diferentes influencias ecológicas y ambientales. Basados en que la disponibilidad de alimento afecta al crecimiento somático de los otáridos y que la abundancia poblacional puede afectar la competencia intrasexual en machos, pensamos que podría existir diferencias regionales entre las colonias del lobo marino de Galápagos (LMG, Zalophus wollebaeki) como resultado de la variabilidad ambiental y distintas abundancias poblacionales. Usamos medidas craneales relacionadas con el tamaño del individuo (secciones que definen sólo crecimiento) y la agresividad (áreas de inserción de músculos asociados con su comportamiento antagonista). En este contexto, se analizaron 19 medidas lineales para tamaño y 15 para agresividad tomadas en 49 cráneos de machos adultos de LMG. Con base en información ecológica, se dividió el archipiélago en cuatro biorregiones: norte (n = 7), oeste (n = 16), centro (n = 8), y sureste (n = 18). El mejor modelo de análisis discriminante flexible basado en el criterio Lambda de Wilk (P < 0,001), contenía nueve de las medidas del cráneo que tuvieron un efecto significativo en la agrupación individual de las biorregiones (P < 0.001). Las medidas más discriminatorias fueron la longitud del hocico: SL, ancho proceso supraorbital: SPW, longitud nasal: NL y ancho canino: CW (Lambda de Wilk P < 0.3). Encontramos una asociación significativa entre los patrones de agrupamiento del cráneo con los niveles de clorofila-α (proxy de productividad marina y crecimiento corporal) y la abundancia de población GSL (proxy de comportamiento agonista) de cada biorregión, así como con la interacción entre ambas variables (modelo lineal). Nuestros resultados sugieren diferencias regionales en la morfometría del LMG, que podrían estar asociadas con una distinta disponibilidad de recursos y nivel de competencia intrasexual en machos en el archipiélago. Esta información es relevante para entender la historia de vida de esta especie, así como sus oportunidades y amenazas.

Dental microwear texture analysis (DMTA) is commonly used to assess the dietary ecology of modern and fossil taxa. In carnivorans, teeth with different functions record dietary behavior differently. Here, we assess DMTA variability along the tooth row of an extant carnivorous marsupial—the Tasmanian devil, Sarcophilus harrisii—which has multiple carnassial-like molars that may function and record diet similarly. We compared the complexity (Asfc), anisotropy (epLsar), and textural fill volume (Tfv) of the lower second, third, and fourth molars of Tasmanian devils to test the hypothesis that teeth with similar forms yield similar functions. Although third molars do have significantly higher epLsar values than fourth molars, all other DMTA attributes are indistinguishable from one another. These data suggest that teeth with comparable morphologies in the same taxon have similar functions and largely record diet similarly. In addition, we compared fossil and modern specimens of S. harrisii from Tasmania to assess dietary behavior over time. These analyses indicate that foods with similar textures have been consumed since the late Quaternary.

Climate has long been recognized as one of the main determinants of the geographical distribution of species. Variations associated with primary productivity in temperature, rainfall, and photoperiod can affect survival and reproduction, affecting the peripheries of geographical distributions. The importance of graphical visualization of these distributions lies in conservation, management, and environmental research. With respect to the South American species of mustelids, 37% are threatened according to the IUCN Red List, and the limits of distributions and their determinants are poorly known for the majority of species. Here, complete and updated databases and maps of geographical and temporal distribution are presented for the 12 species of mustelids inhabiting South America. Museum specimens and recorded localities were gathered based on an online search. Geographic limits of distributions were assessed, as were environmental values for all localities. Comparison with IUCN maps was undertaken to determine the need for updating. Finally, sympatry and syntopy among species analyzed were examined using Geographic Information Systems. The most complete and updated database of geographic distributions of South American mustelids to date was assembled for all species, encompassing 9,826 localities. New areas with recorded localities not present in IUCN maps were documented in many species, indicating the need to update current maps for conservation efforts. Areas of sympatry and syntopy were found among many species, indicating that patterns of coexistence between them are not well known. This study will serve as a framework for ensuing efforts in species distribution modeling, conservation decisions, and field studies, among others.

El clima ha sido reconocido durante mucho tiempo como el mayor determinante de la distribución geográfica de las especies. Las variaciones de temperatura, precipitaciones, y fotoperíodo asociados a la productividad primaria pueden afectar la supervivencia y reproducción, marcando los límites de las distribuciones geográficas de las especies. Las visualizaciones gráficas de las distribuciones son vitales para la conservación, manejo y estudios ambientales. De la fauna de mustélidos sudamericana, el 37% se encuentra en una de las categorías de amenaza de la Lista Roja de la Unión Internacional para la Conservación de la Naturaleza (UICN), mientras que los límites de distribución y sus determinantes son desconocidos para la mayoría de estas especies amenazadas. En este estudio, se presentan bases de datos y mapas actualizados de la distribución geográfica y temporal de las 12 especies de mustélidos presentes en Sudamérica. Se utilizaron localidades provenientes de especímenes de museos junto a una extensa búsqueda de registros de mustélidos online. Se evaluaron los límites geográficos de distribución y los valores de las variables ambientales para todas las localidades. Se realizaron comparaciones con los mapas de la UICN para analizar si una actualización del mapa de distribución sería necesaria. Por último, se evaluó la presencia de simpatría y sintopía de las especies analizadas utilizando Sistemas de Información Geográfica. Se colectó un total de 9.826 localidades para todas las especies de mustélidos, representando así la base de datos más actualizada de la distribución geográfica de este grupo en América del Sur. Se identificaron áreas con registros de mustélidos, que están ausentes en los mapas de la UICN, indicando la necesidad de actualización de los mapas relacionados a los esfuerzos de conservación. Se encontraron áreas de simpatría y sintopía para muchas especies, indicando que los patrones de coexistencia entre varias especies de mustélidos no son bien conocidos. Este estudio servirá como línea de base para el desarrollo de futuros análisis, incluyendo modelos de distribución, decisiones de conservación, y estudios de campo, entre otros.

Long-beaked echidnas (Zaglossus spp.) have received less attention in the literature than Short-beaked echidnas (Tachyglossus aculeatus). Their natural history, anatomy, and physiology are poorly known. To improve our understanding of this unique group, we undertook a radiographic study of the Eastern long-beaked echidna (Zaglossus bartoni), and provide a comparative analysis of its radiographic skeletal anatomy with that of T. aculeatus. We examine conventional radiography and computed tomographic images of Zaglossus and Tachyglossus, describe the anatomical features of Zaglossus, and compare those with Tachyglossus. We provide evidence of epicoracoid overlap in echidnas, a feature not well documented in monotremes. The significance of epicoracoid overlap requires further investigation. Our study is intended as a reference for the radiographic anatomy of Z. bartoni.

Many mammals cross large rivers to access seasonal habitats, yet river crossing behavior is poorly acknowledged or understood. Crossing large rivers is inherently risky, with vessel traffic and flooding events increasing the risk of drowning. We investigated river crossing behavior by threatened bison (Bison bison) in the boreal forest, using data from 11 GPS-collared animals to identify when and where they cross a major river. We used kernel densities of GPS locations to identify crossing hotspots, and developed resource selection function (RSF) models that used habitat characteristics to explain crossing behavior based on a priori hypotheses. We then predicted high-probability crossing areas along a 400-km stretch of river using the best-supported RSF model. Bison regularly crossed the river (x̄ = 8.6 crossings/100 days), particularly during summer months. Model selection results suggested that bison may have chosen river crossing areas that maximized access to forage. Bison preferred to cross the river near islands and areas with high seismic line densities, both of which were likely preferred summer foraging habitats. In addition, islands may have been used as temporary stopovers while crossing the river, or for relief from biting insects. Bison crossed the river where the channel was relatively narrow (x̄ = 400 ± 213 m [SD]) and chose days when river discharge was low, likely to reduce the risk of drowning, exhaustion, or hypothermia. While based on a small sample of collared bison, predictions about high-probability crossing areas may be used to inform mitigation measures aimed at reducing bison drowning caused by vessel traffic, which is expected to increase as resource development expands in the region. Our approach may be informative for identifying river crossing hotspots for other mammals that cross major rivers.

When making foraging decisions, animals evaluate the risk of being preyed upon or hunted. This applies particularly to large-bodied, long-lived species with a long evolutionary history of human persecution, such as wild boars (Sus scrofa). Wild boar populations are rapidly expanding throughout natural, agricultural, and urban areas worldwide, thus escalating human–wild boar conflicts. Most of these conflicts are associated with crop and garden damages by foraging wild boars. To study the foraging behavior of wild boars across a gradient of human risk, we evaluated the combined effects of hunting, land use type, and wild boar group size and structure on boar use of feeding devices. We installed corn-supplemented feeding devices in four land-use types and hunting combinations: urban areas with and without hunting, rural areas (namely, agricultural areas with hunting), and nature reserves without hunting. Our results show that rural areas and urban areas were the most important predictors of the wild boars' decision to eat or not and the time it took them to start eating from the moment they arrived at the feeding device (TBE—Time Before Eating). In addition, our study suggests that the TBEs of urban boars were significantly lower compared to boars from nature reserves. We further found that TBEs of urban boars were significantly lower than TBEs of boars in nature reserves. Our results suggest that the foraging behavior of wild boars varies spatially, corresponding to the different land-use types. We propose that the readiness of boars to forage in urban areas results from their habituation to human presence and lower perception of risk.

Habitat selection is a dynamic biological process where species respond to spatiotemporal variation in resource availability. The resulting distribution patterns can be detected as presence–absence or heterogeneity in abundance and indicate habitat preferences based on environmental correlations at multiple scales. Variation in habitat selection by ungulates is constrained by trade-offs in top-down and bottom-up trophic processes arising from differences in forage requirements, water dependency, anthropogenic effects, and predation avoidance, and mediated by physiological (feeding guild) and morphological (body size) factors. We conducted distance sampling over 7 years in the Tarangire Ecosystem (TE) of northern Tanzania for six resident ungulate species: Kirk's dik-dik (Madoqua kirkii), Grant's gazelle (Nanger granti), Thomson's gazelle (Eudorcas thomsonii), Masai giraffe (Giraffa camelopardalis tippelskirchi), impala (Aepyceros melampus), and common waterbuck (Kobus ellipsiprymnus), and tested hypotheses related to effects of top-down and bottom-up processes on ungulate presence and abundance. We modeled ecological correlates against two distributional responses to understand which environmental factors constrained these ungulate species at different scales; (i) presence–absence observations modeled in a logistic regression to assess habitat selection at an ecosystem scale; (ii) local abundances from presence-only observations modeled using a negative binomial distribution for finer-scale selection. Browser and grazer species in the TE selected suitable habitat proximal to rivers and avoided the Combretum–Azanza woody plant assemblage. Browsers and grazers also showed strong preference for habitat with more dense cover of preferred forage species, and abundance was influenced by the presence of specific forage species with significant seasonal variation. Mixed feeders were more heterogeneous in habitat suitability implying that broader diets allow avoidance of areas with high human activity. Small-bodied and dehydration-sensitive species selected areas near rivers and seasonal tributaries. Seasonal habitat selection was more pronounced among mixed feeders. Conservation strategies based on spatially and seasonally explicit resource selection studies such as ours can minimize impacts to biodiversity by protecting vital resources to ungulates through all seasons of the year.

Hypothesized reasons for the decline of many woodrat populations in the eastern United States include parasitism by raccoon roundworm (Baylisascaris procyonis; Ascaridida: Ascarididae), hard mast shortages, owl predation, and reductions in suitable structures (e.g., rock crevices) for nest construction. We investigated whether abundance and apparent survival of eastern woodrats (Neotoma floridana) within a successfully reintroduced metapopulation in southern Illinois could be predicted by factors underlying these hypothesized reasons for woodrat declines. We analyzed capture histories of 205 eastern woodrats from eight rock outcrop sites in summers of 2013 and 2014 to estimate local population size and apparent survival. We then used repeated-measures models to test how woodrat abundance and apparent survival were associated with availability of mast trees, owl abundance, risk of raccoon roundworm infection, and crevice availability. Mean monthly estimated woodrat abundance at sites ranged from 0.78 to 21.58 in 2013 and 0.48 to 18.08 in 2014, while monthly apparent survival ranged from 0.00 to 0.76 during the summers and 0.05 to 0.90 during the trapping intersession. Crevice availability was positively associated both with abundance and apparent survival of woodrats. Our results did not support the hypothesis that owls reduce woodrat populations because woodrat abundance was positively associated with owl abundance across sites. No raccoon roundworm eggs were found at any site. We conclude that crevice availability was the best predictor of woodrat population success in our study area, while owl abundance may be a proxy for other habitat variables or a response to woodrat abundance. Our findings suggest measures that could be taken to benefit woodrat survival and abundance.

Comparative studies of closely related species provide a powerful means of identifying the ecological and demographic factors associated with variation in mammalian social systems. Although most members of the subterranean rodent genus Ctenomys are thought to be solitary, the highland tuco-tuco (C. opimus) is group living, meaning that multiple adults share a burrow system and underground nest site. These animals are part of the opimus clade, a monophyletic collection of four named species that occur in northwestern Argentina and adjacent portions of Chile and Bolivia. As a first step toward generating a comparative assessment of social organization within this clade, we characterized spatial relationships among members of a population of Ctenomys at Antofagasta de la Sierra, Catamarca Province, Argentina. Based on geographic location and natural history, these animals were expected to be part of the opimus clade; analyses of mitochondrial cytochrome-b sequences from our study population confirmed this general phylogenetic placement. Radiotelemetry data indicated that the animals at Antofagasta were group living, with up to three adult females and one adult male sharing a burrow system. In contrast to other group-living ctenomyids, however, individuals did not consistently share nest sites. Comparisons of these data with re-analyses of spatial relationships among members of the population of C. opimus studied by O'Brien et al. (2020) revealed several intriguing differences in social organization, potential explanations for which include short-term responses to variable demographic and ecological conditions as well as more enduring responses to differences in local selective pressures. Further comparative analyses of these populations and, more generally, members of this subclade of Ctenomys will help to elucidate the factors contributing to variation in social behavior within this speciose and geographically widespread genus.

Los estudios comparativos de especies estrechamente relacionadas proporcionan un recurso eficaz para identificar los factores ecológicos y demográficos asociados con la variación en los sistemas sociales de los mamíferos. Aunque se cree que la mayoría de los miembros del género de roedores subterráneos Ctenomys son solitarios, el tuco-tuco andino (C. opimus) vive en grupos, lo que significa que varios adultos comparten el sistema de túneles y el nido (O'Brien et al. 2020). Esta especie forma parte del clado opimus, un grupo monofilético con cuatro especies reconocidas, distribuidas en el noroeste de Argentina y partes adyacentes de Chile y Bolivia. Como primer paso para generar una evaluación comparativa con base filogenética de la organización social dentro del clado, caracterizamos las relaciones espaciales entre los miembros de una población de Ctenomys en Antofagasta de la Sierra, Provincia de Catamarca, Argentina. En base a su ubicación geográfica e historia natural, se esperaba que estos animales fueran parte del clado opimus. Así, los análisis de las secuencias del citocromo b mitocondrial de nuestra población de estudio confirmaron esta ubicación filogenética general. Los datos de radiotelemetría revelaron que los animales de Antofagasta viven en grupo, con hasta tres hembras adultas y un macho adulto compartiendo el sistema de túneles. Sin embargo, a diferencia de otros ctenomidos que viven en grupo, usualmente los individuos no compartieron regularmente los nidos. La comparación entre los datos de este trabajo con los nuevos análisis de las relaciones espaciales entre los miembros de la población de C. opimus estudiados por O'Brien et al. (2020) revelan diferencias notables en la organización social, cuyas potenciales explicaciones incluyen respuestas a corto plazo debido a la variabilidad en la demografía y en las condiciones ambientales, así como también respuestas a largo plazo como resultado de diferentes presiones de selección locales. Futuros análisis comparativos entre estas poblaciones y entre miembros de este clado de Ctenomys ayudarán a dilucidar los factores que contribuyen a la variación en el comportamiento social dentro de este género específico geográficamente extendido.