Red-nosed mice (genus Wiedomys) are restricted to the Brazilian Cerrado and Caatinga biomes, distributed along the São Francisco River (SFR). Until recently, Wiedomys was considered monotypic, but 2 species with poorly defined geographic and morphological limits have been recognized: W. cerradensis and W. pyrrhorhinos. Our study used morphological, phylogenetic, and cytogenetic analyses to review and detail species limits within the genus and test whether the SFR could be associated with divergence between lineages. This integrative approach indicated that the SFR delineates the geographic boundaries between species, with W. pyrrhorhinos on the right bank and W. cerradensis on the left bank. The species are reciprocally monophyletic and diverge in cranial size, nasal morphology, and facial pelage color pattern. Karyotypic differences between and within W. pyrrhorhinos and W. cerradensis were also detected, and new chromosome complements (2n = 62, FN = 96 and 2n = 62, FN = 88, respectively) were found. Divergence time (0.339 to 0.025 Ma) is concordant with the timing of diversification of other co-distributed vertebrate taxa, and close to a younger estimate for the formation of SFR's recent lower course to the east coast. Therefore, our study considerably expands knowledge of the geographic range of the genus, diagnoses of species, karyotypic variability between and within species, and reinforces the role of SFR as an important vicariant barrier in northeastern Brazil.

Os ratos-bico-de-lacre (gênero Wiedomys) estão restritos aos biomas brasileiros do Cerrado e da Caatinga, distribuídos ao longo do rio São Francisco (RSF). Até recentemente, Wiedomys era considerado monotípico, mas duas espécies com limites geográficos e morfológicos pouco detalhados foram reconhecidas: W. cerradensis e W. pyrrhorhinos. No presente estudo, tivemos como objetivo revisar e detalhar os limites das espécies dentro do gênero e testar se o RSF poderia estar associado à divergência entre as linhagens, usando análises morfológicas, filogenéticas e citogenéticas. Esta abordagem integrativa indicou que o RSF é concordante com os limites geográficos das duas espécies, com W. pyrrhorhinos na margem direita e W. cerradensis na margem esquerda. As espécies são reciprocamente monofiléticas e divergem quanto ao tamanho do crânio, morfologia nasal e padrão de coloração da pelagem facial. Diferenças cariotípicas entre e dentro de W. pyrrhorhinos e W. cerradensis também foram detectadas, e novos complementos cromossômicos (2n = 62, NF = 96 e 2n = 62, NF = 88, respectivamente) foram reportados. O tempo de divergência (0,339-0,025 Ma) é concordante com eventos de diversificação em outros táxons de vertebrados co-distribuídos e se aproxima à estimativa mais recente para a formação do baixo curso do RSF. Portanto, nosso estudo expande consideravelmente o conhecimento sobre as distribuições geográficas do gênero, as diagnoses das espécies e suas variabilidades cariotípicas, e também indica o RSF como uma potencial barreira vicariante para o gênero Wiedomys no Nordeste do Brasil.

Due to the disproportionate role that large carnivores can have on communities and their global decline over the last century, carnivores are increasingly being repatriated across their historic ranges. The reintroduction of gray wolves (Canis lupus) can precipitate substantive changes to communities and ecosystems. Notably, wolves could have strong effects on smaller and subordinate carnivores, especially in altering their foraging behavior and prey selection. Past studies investigating wolf effects on other carnivores, however, have generally been conducted in relatively complex communities featuring a diverse assemblage of carnivores and prey and have lacked baseline (i.e., pre-repatriation) data. Consequently, researchers have quantified what a community looks like after wolf return, with little information on how the community behaved before. To better understand the effect of large carnivore repatriation on the foraging ecology of a carnivore community, we investigated the impact of reintroduced gray wolves on 2 meso-carnivores: Red Fox (Vulpes vulpes); and American Marten (Martes americana) within an insular and simple vertebrate community at Isle Royale National Park before and after wolf reintroduction. We analyzed >600 scats from 20 individual martens and 63 individual foxes as well as the stable isotopes of 9 and 22 tissue samples from martens and foxes, respectively, at both individual and population levels. We found that the wolf reintroduction had little effect on marten diet but strongly influenced fox diet depending on the analysis conducted. At the population level, our analysis revealed that both foxes and martens were dietary generalists consuming an array of food items including small prey, berries, and human food regardless of wolf presence. However, at the individual level, we found that prior to wolf repatriation foxes primarily consumed berries and small prey but following wolf repatriation the diet of foxes shifted to berries and human foods as well as large carrion. This post-wolf reintroduction shift in diet increased the dietary overlap between foxes and martens. Our work provides new insights into how the return of a large carnivore can alter the foraging ecology of small-bodied carnivores and act both to provision carrion resources as well drive other carnivores to consume more human food and increase dietary overlap.

Beavers have occurred in North America since at least 7 Ma, but relatively little is known about their distribution across the continent. We modeled distributions of beavers in the late Pliocene (3.3 Ma), Pleistocene (130 ka and 21 ka), and recent Holocene (1970 to 2000) to understand their dispersal across North America, predict future distributions and predict their possible response to future climate and habitat changes. Occurrence data for Castor canadensis were derived from the Global Biodiversity Information Facility. Those data were used with both modern (1970 to 2000) and modeled future (EC-Earth-Veg 2081 to 2100) bioclimatic variables from WorldClim as well as past (Pliocene Marine Isotope Stage M2, Pleistocene Last Interglacial, and Pleistocene Last Glacial Maximum) bioclimatic variables from PaleoClim to model beaver distributions through time. Fossil locality points for Castor extracted from the New and Old Worlds Database of Fossil Mammals (NOW), NEOTOMA Paleoecology Database, and Paleobiology Database were overlain on past projection models to use as validation points. Models were run using MaxEnt with post-processing in ArcGIS. Accuracy for the 5 models ranged between 59.6% and 60.2%. Results for the present model (1970 to 2000) showed habitat suitability in areas beavers inhabit today. During the Pliocene MIS M2 cooling event (3.3 Ma) and Pleistocene Last Glacial Maximum (21 ka), habitat suitability shifted further south into Mexico and peninsular Florida and away from more periglacial northern regions. During the Last Interglacial period (130 ka) and modeled future (2081 to 2100) EC-Earth-Veg 2081 to 2100, habitat suitability was higher in coastal and central regions in North America and lower in southern regions compared to their present distribution. Distributions were most affected by precipitation seasonality, isothermality, and mean annual temperature. High variability in seasonal precipitation and temperatures is likely to influence surface water availability, vegetation type, and riparian vegetation composition, which consequently may reduce available food resources and habitat for beavers. Observed shifts during warmer periods may indicate areas in the late Miocene that facilitated dispersal into North America. Future models using other predicted climatic scenarios and shared socioeconomic pathways may provide better resolution of potential future shifts in beaver distribution with best- and worst-case climate scenarios, thereby permitting at-risk areas to be prioritized for conservation in the face of climate change.

Los castores han estado presentes en América del Norte desde hace al menos 7 Ma, pero se sabe relativamente poco sobre su distribución en el continente. Modelamos las distribuciones de los castores en el Plioceno tardío (3.3 Ma), el Pleistoceno (130 ka y 21 ka) y el Holoceno reciente (1970-2000) para comprender su dispersión en América del Norte, predecir distribuciones futuras y predecir su posible respuesta a futuros cambios climáticos y de hábitat. Los datos de presencia de Castor canadensis se derivaron del Global Biodiversity Information Facility. Esos datos se usaron con variables bioclimáticas modernas (1970-2000) y futuras modeladas (EC-Earth-Veg 2081-2100) de WorldClim, así como variables bioclimáticas pasadas (Plioceno Marine Isotope Stage M2, Pleistoceno Last Interglacial, Pleistoceno Last Glacial Maximum) de PaleoClim para modelar las distribuciones de los castores a lo largo del tiempo. Los puntos de localidad fósil de Castor extraídos de la Base de datos de mamíferos fósiles del Nuevo y Viejo Mundo (NOW), la Base de datos de paleoecología NEOTOMA y la Base de datos de paleobiología se superpusieron a modelos de proyección anteriores para usarlos como puntos de validación. Los modelos se ejecutaron utilizando MaxEnt con posprocesamiento en ArcGIS. La precisión de los 5 modelos osciló entre el 59.6 y el 60.2%. Los resultados del modelo actual (1970-2000) mostraron la idoneidad del hábitat en las áreas que habitan los castores en la actualidad. Durante el evento de enfriamiento MIS M2 del Plioceno (3.3 Ma) y el Último Máximo Glacial del Pleistoceno (21 ka), la idoneidad del hábitat se desplazó más al sur hacia México y la península de Florida y se alejó de las regiones más periglaciales del norte. Durante el último período interglacial (130 ka) y el futuro modelado (2081-2100) EC-Earth-Veg 2081-2100, la idoneidad del hábitat era mayor en las regiones costeras y centrales de América del Norte y menor en las regiones del sur en comparación con su distribución actual. Las distribuciones se vieron más afectadas por la estacionalidad de las precipitaciones, la isotermalidad y la temperatura media anual. Es probable que la alta variabilidad en las precipitaciones y temperaturas estacionales influya en la disponibilidad de agua superficial, el tipo de vegetación y la composición de la vegetación ribereña, lo que en consecuencia puede reducir los recursos alimentarios y el hábitat disponibles para los castores. Los cambios observados durante los períodos más cálidos pueden indicar áreas en el Mioceno tardío que facilitaron la dispersión en América del Norte. Los modelos futuros que utilicen otros escenarios climáticos previstos y vías socioeconómicas compartidas pueden proporcionar una mejor resolución de los posibles cambios futuros en la distribución de los castores con los mejores y peores escenarios climáticos, lo que permitirá priorizar las áreas en riesgo para la conservación frente al cambio climático.

Dens play a crucial role in the survival of young and can ultimately affect population dynamics for felid carnivores. However, little is known about Bobcat (Lynx rufus) den site selection. Therefore, this study aimed to identify environmental correlates of Bobcat den sites in the Black Hills, South Dakota, United States. Our objectives for this study were to compare environmental characteristics of Bobcat dens to random sites at coarse (3.14 ha) and local (0.05 ha) spatial scales. Female bobcats were radio-collared (n = 35) and dens (n = 27) were located using ground telemetry. Bobcats selected for high horizontal cover and terrain ruggedness at the coarse scale, as well as high horizontal cover at the local scale, which could provide concealment from predators. In less rugged areas land management practices that promote increased tree and shrub habitat as horizontal cover may provide habitat for Bobcat dens and ensure the survival of this ecologically and culturally important species.

Las madrigueras desempeñan un papel crucial en la supervivencia de las crías y, en última instancia, pueden afectar la dinámica de la población de los carnívoros felinos. Sin embargo, se sabe poco sobre la selección del sitio de guarida del gato montés (Lynx rufus). Por lo tanto, este estudio tuvo como objetivo identificar correlatos ambientales de los sitios de guarida del gato montés en Black Hills, Dakota del Sur, EE UU. Nuestros objetivos para este estudio fueron comparar las características ambientales de las madrigueras del gato montés con sitios aleatorios en escalas espaciales generales (3.14 ha) y locales (0.05 ha). Se colocó un collar de radio a las hembras del gato montés (n = 35) y se localizaron las madrigueras (n = 27) utilizando telemetría terrestre. Los gato montés se seleccionaron por su alta cobertura horizontal y la irregularidad del terreno en la escala general, así como por su alta cobertura horizontal en la escala local, lo que podría proporcionar ocultamiento de los depredadores. En áreas menos accidentadas, las prácticas de manejo de la tierra que promueven un mayor hábitat de árboles y arbustos como cobertura horizontal pueden proporcionar hábitat para las madrigueras del gato montés y garantizar la supervivencia de esta especie ecológica y culturalmente importante.

Providing novel food subsidies to wildlife can influence behavior, resource use, disease dynamics, and food web interactions. Studies examining impacts of anthropogenic food have primarily occurred in urban landscapes where anthropogenic resources are consistently accessible. National parks, however, experience similar issues regarding wildlife exploiting anthropogenic food, but access to anthropogenic food is contingent on human visitation, which can fluctuate dramatically between seasons. We evaluated how fluctuating availability of anthropogenic food and demographic factors influenced the isotopic niche of Rocky Mountain Red Fox (Vulpes vulpes macroura) at the population and individual level in Grand Teton National Park, Wyoming. From 2016 to 2021, we assessed diet-related questions by collecting 55 whisker samples and 52 hair samples from 40 unique individuals and analyzed them using stable isotope analysis (δ¹³C and δ¹⁵N). We discovered that Rocky Mountain red foxes have a broad isotopic niche, with seasonal differences in their consumption of anthropogenic food. Contrary to our expectations, foxes demonstrated increased reliance on anthropogenic food (higher δ¹³C values) during winter months, whereas natural food consumption or dietary mixing was more prominent in summer months. Natural food scarcity could be driving foxes to seek out more anthropogenic food in the winter, whereas the increased abundance of natural food items in the summer could result in a lower need for foxes to supplement their diet with anthropogenic food. Adults had consistently higher δ¹³C values relative to juveniles, indicating either intraspecific variation in boldness or dominance leading to increased exploitation of anthropogenic food, which could be a learned behavior coinciding with habituation. Finally, we observed that increasing densities of human features within the home range of a fox was a strong predictor of anthropogenic food reliance at the individual level. Our work provided a deeper understanding of the trophic ecology of Rocky Mountain Red Fox in relation to human activity in a nature preserve, and equipped managers with insight into potential patterns associated with food-conditioned foxes.

The California sea lion (Zalophus californianus; CSL) reflects environmental conditions of the Northeastern Pacific, where resource availability was importantly reduced for different taxa during climatic variations such as the North Pacific heatwave (The Blob 2014 to 2015) or El Niño 2015 to 2016 due to the effect of these anomalies on primary productivity. Our objective was to determine the abundance and foraging habits of CSLs from the San Benito Archipelago (Mexican Pacific) in a period (2013 to 2019) that involved warm anomalies. Annual counts were conducted by sex/age classes; scats were sampled to identify the main prey consumed; and pup fur (maternal foraging indicators) was collected for analysis of δ¹³C and δ¹⁵N. The prey importance index (PII) and trophic level were calculated and the Siber assessment in R was used to estimate isotopic niches. Colony abundance decreased by approximately 50% from 2013 to 2019. Values of δ¹³C showed significant interannual differences (P < 0.001) with more negative values (–17.2‰ to –16.7‰) from 2015 onwards, indicating offshore foraging habits. Significant interannual differences (P < 0.001) were found for δ¹⁵N, with a declining trend (20.4‰ to 19.07‰), and a difference of more than 1‰ between 2013 and 2019, evidencing a probable shift of foraging grounds toward higher latitudes. Based on the PII, Strongylura exilis (30%), Merluccius productus (24%), Ommastrephes bartramii (10%), and Sardinops sagax (10%) were the most important prey, showing significant interannual differences (P < 0.001). CSLs had a mean trophic level of 4.89, with a slight increasing trend toward the end of the period. Dietary plasticity was found in CSLs, possibly caused by environmental changes that modified prey availability and led to variations in foraging grounds, and consequently in the colony abundance over time.

La ecología trófica del Lobo Marino de California (Zalophus californianus; LMC) refleja las condiciones ambientales del Pacífico Nororiental, donde la disponibilidad de recursos se redujo de manera importante para diferentes taxones durante variaciones climáticas, tales como la ola cálida del Pacífico Norte (La Mancha 2014 a 2015) o El Niño-Oscilación del Sur 2015 a 2016, debido al efecto de estas anomalías oceanográficas sobre la productividad primaria. Nuestro objetivo fue determinar la abundancia y hábitos alimenticios del LMC del Archipiélago de San Benito (Pacífico Mexicano) en el periodo (2013 a 2019), en el que se produjeron anomalías cálidas. Se realizaron conteos anuales por clase de sexo/edad; se muestrearon heces fecales para identificar las principales presas consumidas; y se recolectó pelo de crías (indicadores de alimentación materna) para el análisis de δ¹³C y δ¹⁵N. Calculamos el índice de importancia de las presas (IIP) así como el nivel trófico y utilizamos la evaluación de SIBER en R para estimar los nichos isotópicos. La abundancia de colonias de LMC disminuyó aproximadamente un 50% de 2013 a 2019. Los valores de δ¹³C mostraron diferencias interanuales estadísticamente significativas con valores más negativos (–17.2‰ a –16.7‰) a partir de 2015, lo que indicó hábitos alimenticios más oceánicos (alejados de la costa). Se encontraron diferencias significativas interanuales para δ¹⁵N, con una tendencia decreciente (20.4‰ a 19.1‰), y una diferencia de más de 1‰ entre 2013 y 2019, evidenciando un probable desplazamiento de las zonas de alimentación hacia latitudes más altas. Basándose en el IIP, Strongylura exilis (30%), Merluccius productus (24%), Ommastrephes bartramii (10%) y Sardinops sagax (10%) fueron las presas más importantes. Los LMC presentaron un nivel trófico medio de 4.89, con una ligera tendencia al aumento hacia el final del periodo. Se observó plasticidad trófica, como respuesta a cambios ambientales que modificaron la disponibilidad de las presas y provocaron variaciones en las zonas de alimentación y, en consecuencia, en la abundancia de esta colonia de LMC a lo largo del tiempo.

Animals at risk of predation select habitat that enhances security from predators. Two properties of cover related to security are concealment (i.e., habitat structure that blocks an individual from detection by others) and visibility (i.e., visual information accessible relative to habitat structure). Although these properties are often negatively correlated, they are not always inverse; animals in habitat with heterogeneous structure may be able to select for both. We investigated habitat use by pygmy rabbits (Brachylagus idahoensis) at 2 scales (patch and microsite) to evaluate the influence of both structural properties of cover and visual properties (concealment and visibility) on habitat use by prey. We contrasted vegetation structure at paired used and unused patches. At each patch, we measured concealment and viewshed (i.e., visibility) in 3 orientations (i.e., aerial, terrestrial, and overall) and structural density using lidar. We also measured heights of the 3 tallest shrubs. Additionally, within used patches, we assessed the density of fecal pellets as an index of intensity of use and also measured distance to nearest burrow. At the patch scale, rabbits selected for structural properties of cover (dense vegetation and tall shrubs), but not visual properties of cover. Pygmy rabbits more intensively used microsites associated with high terrestrial concealment and in proximity to burrows. Our results suggest that pygmy rabbits may perceive greater threat from terrestrial as opposed to aerial predators at both scales, and they also indicate a nuanced relationship between properties of cover and habitat use.

Animals living in seasonal environments have adopted a wide array of tactics used to deal with seasonal resource scarcity. Many species migrate between habitats to reach areas where food resources are more plentiful as an attempt to address energetic demands through foraging. We assessed the winter behavioral adaptations of Caribou (Rangifer tarandus), a large ungulate inhabiting Arctic and sub-Arctic regions known for seasonal resource scarcity. Movement rates of Caribou are the lowest of the year during winter, revealing 1 mechanism individuals use to reduce energy expenditures. However, migratory individuals moved nearly twice as much as nonmigratory individuals during winter, suggesting that migratory individuals rely more upon income (forage), whereas nonmigratory individuals rely more upon capital (bodily reserves). Lichens are the primary winter forage for large, migratory herds of Caribou, and migratory individuals experienced more than 2.5 times greater lichen cover than nonmigratory individuals. We documented that both groups slowed their movement in areas of greater lichen cover, suggesting increased foraging time in these areas. Movement rates were greater near villages, which may be suggestive of disturbance, but the effect was weak. Overall energy saved by reduced movement rates was modest. However, energy savings were 11% of daily body energy lost or 47% of the demands of early pregnancy, which potentially could affect individual condition and/or fetal growth if not offset by increases in forage intake.

Elucidating factors influencing home range size is fundamental to the ecology and management of wildlife species, particularly those of conservation concern, because they can provide insight into how species utilize and interact with their environment. Variation in home range size can be related to intraspecific competition and social organization, energetic requirements in relation to habitat productivity, allometric relationships, and population density. The Mexican Gray Wolf (Canis lupus baileyi) is an endangered subspecies of the Gray Wolf whose home range size has not yet been studied. We examined ecological and social drivers of home range size of 22 Mexican Wolf packs between 2017 and 2021 across 4 biological time frames: annual; denning; post-denning; and non-denning. We used a 95% Brownian Bridge Movement Model home range estimator and generalized linear mixed-effect models to assess these relationships. Home range size was inversely correlated with estimated ungulate biomass, which was the most influential driver of home range size at annual and post-denning time frames. Larger packs utilized larger ranges during denning and post-denning time frames, while packs with larger litters had smaller ranges during the denning season. Snow depth was inversely related to home range size during the non-denning season. Our results indicate that both ecological and social factors are important and seasonally dependent in driving Mexican Wolf home range size. Use of a multiscale approach in future home range studies could discern relevant factors for species during time frames of interest.

Esclarecer los factores que influyen en el tamaño del área de campeo es fundamental para la ecología y el manejo de lafauna silvestre, particularmente aquellas de interés para la conservación, porque pueden proporcionar información sobre cómo éstas utilizan su entorno. Por ejemplo, la variación en el tamaño del área de campeo puede estar relacionada con la competencia intraespecífica y la organización social, los requerimientos energéticos en relación con la productividad del hábitat, la existencia de relaciones alométricas y la densidad poblacional. El lobo gris mexicano (Canis lupus baileyi) es una subespecie del lobo gris en peligro de extinción cuyo tamaño de área de campeo no se ha estudiado. Examinamos los factores ecológicos y sociales relacionados con el tamaño del área de campeo de 22 manadas de lobos mexicanos entre 2017 y 2021 en 4 períodos de tiempo biológicos: anual, durante la formación de guarida, después de la formación de guarida y sin guarida. Utilizamos el estimador del área de campeo denominado Modelo de Movimiento de Puente Browniano a un 95% y modelos lineales generalizados de efectos mixtos para evaluar estas relaciones. El tamaño del área de campeo se correlacionó inversamente con la biomasa de ungulados estimada, que fue la variable que más influyó en el tamaño del área de campeo en los períodos biológicos anual y después de la formación de guarida. Las manadas más grandes presentaron áreas de campeo más grandes durante la formación de guarida y después de la formación de guarida, mientras que las manadas con camadas más grandes tuvieron áreas de campeo más pequeños durante la formación de guarida. La profundidad de la nieve estuvo inversamente relacionada con el tamaño del área de campeo durante la estación sin guarida. Nuestros resultados indican que tanto los factores ecológicos como los sociales son importantes y que éstos varían estacionalmente para determinar el tamaño del área de campeo del lobo mexicano. El uso de un enfoque multiescala en estudios futuros sobre el área de campeo podría ayudar a determinar factores relevantes para las especies focales durante períodos de tiempo con interés biológico.

The risk of encountering a predator triggers different antipredator strategies in the prey, including spatial (landscape level), temporal (daily activity cycles), and behavioral changes. There is evidence that linear landscape attributes (e.g., dirt roads, firebreaks, trails) are used by both predators and prey, although studies examining how they react to mutual use are scarce. We propose a conceptual model that explains how prey might change their activity patterns under spatial-scale scenarios of predation risk. We test our predictions with Jaguar (Panthera onca) and Puma (Puma concolor) as predators and Collared Peccary (Dicotyles tajacu) as the prey. Peccary activity patterns differed between foraging areas with different levels of predation risk, with low-risk areas showing 2 peaks of activity around dusk, but exclusively diurnal in high-risk areas. The highest overlap coefficient (= 0.82) occurred when comparing peccary activity patterns near linear attributes and high-risk foraging areas, and the lowest (= 0.16) between high-risk foraging areas and Jaguar activity patterns, showing a completely diurnal pattern when the Jaguar was inactive. The overlap coefficient was intermediate (= 0.45) when comparing Puma and peccary activity patterns in high-risk areas. The observed similarity in peccary activity patterns between high-predation-risk foraging areas and linear attributes seems to indicate that the latter are also perceived as high-risk areas that lead to changes in their activity patterns.

El riesgo de encontrarse con un depredador desencadena diferentes estrategias antidepredatorias en la presa, incluyendo cambios espaciales (a nivel de paisaje), temporales (ciclos de actividad diaria) y conductuales. Existe evidencia de que los atributos lineales del paisaje (ej. caminos de terracería, cortafuegos, senderos) son utilizados tanto por depredadores como por presas, aunque los estudios que examinan cómo reaccionan al uso mutuo son escasos. Proponemos un modelo conceptual que explica cómo, las presas podrían cambiar sus patrones de actividad bajo escenarios de riesgo de depredación a escala espacial. Probamos nuestras predicciones con el jaguar (Panthera onca) y el puma (Puma concolor) como depredadores y el pecarí de collar (Dicotyles tajacu) como la presa. Los patrones de actividad del pecarí difirieron entre áreas de forrajeo con diferentes niveles de riesgo de depredación, en las áreas de bajo riesgo mostraron dos picos de actividad alrededor del crepúsculo, mientras que, en las áreas de alto riesgo fue exclusivamente diurno. El coeficiente de traslape más alto (= 0.82) se dio al comparar los patrones de actividad del pecarí en los atributos lineales y las áreas de forrajeo de alto riesgo y el más bajo (= 0.16) entre las áreas de forrajeo de alto riesgo y los patrones de actividad del jaguar, en este caso el pecarí mostró un patrón completamente diurno, cuando el jaguar estaba inactivo. El coeficiente de traslape fue intermedio (= 0.45) al comparar los patrones de actividad del puma y pecarí en las áreas de alto riesgo. La similitud observada en los patrones de actividad del pecarí entre las áreas de forrajeo de alto riesgo de depredación y los atributos lineales parece indicar que también son percibidos como áreas de alto riesgo que conducen a cambios en sus patrones de actividad.

In this study, we investigated landscape variability of the carbon and nitrogen isotopic composition of nonvolant small mammals in the 3 main Brazilian biomes (Amazon, Atlantic Forest, and Cerrado) while also considering the differential spatial distribution of C₄ plants in these biomes. We compiled a subset of data on stable carbon and nitrogen isotope ratios from nonvolant small mammals of the order Rodentia and compared the aggregated isotopic variability at the biome level using classical δ¹³C–δ¹⁵N biplot. The concept of isotopic niche width was used to test whether different foraging attributes drive their isotopic composition, while a Bayesian isotopic mixing model was used to estimate the proportion of 3 main food categories available to these small mammals. We also developed isoscapes in the Brazilian biomes, interpolating animals δ¹³C and δ¹⁵N based on the geographic coordinates of each sample and “sourcescapes” considering geographic variation of the dietary sources. The findings of this study advance our understanding of the foraging ecology of small mammals in biodiversity-rich regions of the Neotropics. Classical methodologies such as stomach content confirmed dietary choices revealed by the stable isotopic composition and also highlighted the importance of C₃ and C₄ plants in the diet of this group of animals, especially in biomes such as the Atlantic Forest and Cerrado, where there is a predominance of highly altered landscapes. These results confirm that replacing the original vegetation with C₄ crops has altered the feeding patterns of small mammals, which could lead to critical ecological changes in the trophic structure of these areas. Vertical stratification of the dietary niche and the interaction between biome and foraging lifestyle were also observed. However, in each biome, there was significant intraspecific and interspecific variation caused by preferences for ingestion of plant and animal material, leading to different degrees of omnivory. Finally, the high local variability between individuals and species requires a larger sampling design that may also contribute to improved spatial resolution of the isoscapes.

Neste estudo, investigamos a variabilidade da composição isotópica de carbono e nitrogênio de pequenos mamíferos não-voadores em biomas brasileiros (Amazônia, Mata Atlântica e Cerrado), levando em conta a distribuição espacial de plantas C₄ nesses biomas. Compilamos dados de mamíferos da ordem Rodentia e comparamos a variabilidade isotópica agregada ao nível do bioma utilizando o biplot δ¹³C–δ¹⁵N. O conceito de amplitude de nicho isotópico foi empregado para testar se diferentes estratégias de forrageamento influenciam a composição isotópica desses animais, enquanto um modelo Bayesiano de mistura isotópica foi utilizado para estimar a proporção das três principais categorias alimentares. Desenvolvemos isoscapes do território brasileiro, interpolando δ¹³C e δ¹⁵N dos animais com base nas coordenadas geográficas de cada amostra, e “sourcescapes,” considerando a variação geográfica das fontes alimentares. Os resultados deste estudo avançam nossa compreensão da ecologia de pequenos mamíferos em regiões ricas em biodiversidade dos Neotrópicos. Metodologias clássicas, como a análise do conteúdo estomacal, confirmaram as escolhas alimentares reveladas pela composição isotópica, destacando a importância das plantas C₃ e C₄ na dieta desses animais, especialmente em biomas com paisagens altamente alteradas, como a Mata Atlântica e o Cerrado. A substituição da vegetação original por culturas C₄ alterou os padrões alimentares dos pequenos mamíferos, potencialmente levando a mudanças críticas na estrutura trófica dessas áreas. Observamos também a estratificação vertical do nicho alimentar e a interação entre o bioma e a estratégia de forrageamento. No entanto, em cada bioma, houve variação intraespecífica e interespecífica causada pela preferência de ingestão de material vegetal e animal, resultando em diferentes graus de onivoria. Além disso, a alta variabilidade local recomenda uma maior amostragem para melhorar a resolução espacial das isoscapes.

White-nose syndrome (WNS) has caused dramatic population declines in several bat species, including the Tricolored Bat (Perimyotis subflavus). Several studies have documented bats using colder roosting temperatures after infection; however, this strategy may have costs such as increased freezing risks or greater predation risks and it is unknown when during hibernation bats begin to utilize these colder temperatures. Our aim was to examine Tricolored Bat roost locations in a WNS-positive site in relation to roost microclimate and other environmental conditions throughout the hibernation season. We conducted monthly censuses of tricolored bats across 2 hibernation seasons (November to March 2020 to 2021 and October to March 2021 to 2022) in a WNS-positive hibernaculum in northwestern South Carolina and recorded skin and adjacent wall temperature, tunnel section, and distance from the entrance for each bat species. We continuously measured hibernacula temperature and relative humidity during both hibernation seasons. Most bats roosted in the back part of the tunnel where temperatures were warmer and more stable, and vapor pressure deficit (VPD) and human disturbance were low. However, >20% of bats roosted in the front, where roost temperatures were significantly colder and VPD was higher but more variable; human disturbance was also higher in this section. The proportion of bats in each tunnel section did not vary among months and we did not find evidence of significant movement to the front section of the tunnel as hibernation progressed based on marked bats; however, bats in the front section roosted higher on the wall suggesting that they may be avoiding human disturbance or predators. Our results support the notion that no optimum hibernation temperature exists for tricolored bats and that high VPD and disturbance are likely important factors driving microsite use. Protection of Tricolored Bat hibernacula that offer a range of microclimates or a network of sites in close proximity that offer different microclimates may be helpful for recovery of this species.

El síndrome de la nariz blanca (WNS por sus siglas en inglés) ha provocado una disminución drástica en las poblaciones de varias especies de murciélagos, incluido el murciélago tricolor (Perimyotis subflavus). Varios estudios han documentado que los murciélagos utilizan temperaturas de descanso más frías después de la infección; sin embargo, esta estrategia puede tener costos tales como mayores riesgos de congelación o mayores riesgos de depredación, y se desconoce en qué momento de la hibernación los murciélagos comienzan a utilizar estas temperaturas más frías. Nuestro objetivo fue examinar ubicaciones de descanso del murciélago tricolor en un sitio WNS-positivo en relación con el microclima de descanso y otras condiciones ambientales durante la temporada de hibernación. Realizamos censos mensuales de murciélagos tricolores durante 2 temporadas de hibernación (noviembre-marzo de 2020 a 2021 y octubre-marzo de 2021 a 2022) en un hibernáculo WNS-positivo en el noroeste de Carolina del Sur y registramos la temperatura de la piel y de la pared adyacente, la sección del túnel y la distancia desde la entrada para cada especie de murciélago. Medimos continuamente la temperatura y la humedad relativa del hibernáculo durante las dos temporadas de hibernación. La mayoría de los murciélagos se posaron en la parte trasera del túnel, donde las temperaturas eran más cálidas y estables, y el déficit de presión de vapor (VPD por sus siglas en inglés) y la perturbación humana eran bajos. Sin embargo, el >20% de los murciélagos se posaron en la parte delantera, donde las temperaturas de los sitios de descanso eran significativamente más frías y el VPD era más alto, pero más variable; la perturbación humana también era mayor en esta sección. La proporción de murciélagos en cada sección del túnel no varió entre meses y no encontramos evidencia de un movimiento significativo hacia la sección delantera del túnel a medida que avanzaba la hibernación según los murciélagos marcados; sin embargo, los murciélagos en la sección delantera se posaron más arriba en la pared, lo que sugiere que podrían estar evitando la perturbación humana o los depredadores. Nuestros resultados respaldan la noción de que no existe una temperatura de hibernación óptima para los murciélagos tricolores y que el alto VPD y la perturbación son probablemente factores importantes que impulsan el uso de micrositios. La protección de hibernáculos del murciélago tricolor que ofrezcan una variedad de microclimas o una red de sitios en estrecha proximidad que ofrezcan diferentes microclimas podría ser útil para la recuperación de esta especie.

Insectivorous bats play an essential role as predators in natural ecosystems and contribute to pest control in agricultural landscapes. However, characterizing diets of specific bat species is difficult using conventional methods that cannot capture detailed dietary information. In this study, we used metabarcoding of the cytochrome oxidase I mitochondrial gene to analyze fecal samples of Myotis velifer and provide insight into the seasonal variation of diet from a colony located in the Chihuahuan Desert region of Texas. After filtering sequence reads, we recovered and analyzed 706 molecular operational taxonomic units (MOTUs) in the diet of M. velifer. We found 484 taxa (species and genus level) belonging to 11 insect orders in 66 fecal samples collected from March to October 2021. The orders containing the most MOTUs were Diptera (n = 353), Lepidoptera (n = 160), and Blattodea (n = 59). In their diet, we identified important insect crop pests, non-native insects, and substantial consumption of mosquitoes. Dietary composition shifted throughout seasons. Bats captured in summer months consumed the highest diversity of arthropod orders, and those captured in the spring consumed more diet items but were less diverse in arthropod orders. Our results uncovered 2 additional orders consumed by M. velifer, Blattodea and Odonata, that have not been previously described in their diet.

Los murciélagos insectívoros son esenciales como depredadores en ecosistemas naturales y contribuyen al control de plagas en paisajes agrícolas. Sin embargo, caracterizar las dietas de especies de murciélagos individuales es difícil, y los métodos convencionales no pueden capturar la información detallada de sus dietas. En este estudio, utilizamos metacódigos de barras del gen mitocondrial citocromo oxidasa I para analizar muestras fecales de Myotis velifer, y generar conocimiento sobre la variación estacional de la dieta de una colonia ubicada en la Región del Desierto de Chihuahua en Texas. Después de filtrar las secuencias genéticas, recuperamos y analizamos 706 unidades taxonómicas operacionales moleculares (UTOMs, MOTUs por sus siglas en inglés) en la dieta de M. velifer. Entre Marzo y Octubre del 2021, colectamos 66 muestras fecales. Encontramos 484 taxones (a nivel de especie y género) que pertenecen a 11 órdenes de insectos. Los órdenes que contenían la mayor cantidad de UTOMs fueron Diptera (n = 353), Lepidoptera (n = 160), y Blattodea (n = 59). Identificamos en la dieta de estos murciélagos importantes grupos de insectos que son considerados plagas en las áreas agrícolas, especies de insectos no nativos y una cantidad considerable de mosquitos. La composición de la dieta cambió a lo largo de las estaciones; los murciélagos capturados en los meses de verano consumieron la mayor diversidad de órdenes de artrópodos en comparación con la primavera que consumieron una mayor cantidad de insectos individuales pero con menor diversidad de órdenes. Nuestros resultados descubrieron dos órdenes adicionales consumidos por M. velifer que no han sido reportadas previamente, Blattodea y Odonata.

We provide the first estimates of survival and reproductive rates for a population of the Gambian Epauletted Fruit Bat Epomophorus gambianus in Ghana. We focused on a large colony of ca. 5,000 bats over 3 years to estimate population parameters including population size, birth rates, survival, and sex ratios for this species. Reproduction chronology was confirmed as seasonal bimodal polyestry, with births occurring in March/April and August/September each year. The estimated birth rate was 0.89 (95% CI = 0.85 to 0.92) per reproductive season. The overall sex ratio (female to male ratio) of the study population was male-dominated (0.69, 95% CI = 0.64 to 0.75), but female-biased for adults (62% female, χ² ₁ = 42, P < 0.0001), and showed temporal and age-specific variations. By radiotracking 60 bats for 10 months, we obtained the first estimates of minimum monthly survival for this species as 0.81 (95% CI = 0.74 to 0.86), but this could be an underestimate due to possible undetected emigration of tagged bats.

In 2018, an adult male of a small-sized Tube-nosed Bat (Chiroptera: Vespertilionidae: Murina) was captured at an arid cave located on the Qinghai–Tibet Plateau in Yushu City, Qinghai Province, China. Despite external morphological similarities with those of M. harpioloides and M. chrysochaetes, the individual in question displays explicit craniodental differences that distinguish it from either species. Morphological and morphometric evidence, coupled with phylogenetic analyses utilizing the mitochondrial COI gene, confirmed that it represents a distinct and still unknown species of Murina, described herewith as M. yushuensis sp. nov. Our research highlights the importance of future surveys aimed at exploring cryptic species diversity in the Qinghai–Tibet Plateau and adjacent under-surveyed regions.

Roughly a third of all horseshoe bat species (Rhinolophidae: Rhinolophus) are found in Africa, where a recent continent-wide genetic survey suggested the presence of both undescribed and apparently invalid species. Here, we focus on the R. landeri species complex and the recent elevation of R. lobatus Peters, 1852, to species rank. That action created ambiguity in the taxonomy of East African members of the group—are both R. landeri Martin, 1838, and R. lobatus sympatric in East Africa or is another, unnamed species present there? Here, we refine genetic, morphological, and behavioral characterizations of R. landeri and its erstwhile synonyms with samples from the vicinity of their type localities. The distribution of R. landeri appears to be limited to Central and West Africa; existing genetic records attributed to this species from Mali clearly represent another taxon. We marshal genetic evidence for the species-level distinction of R. dobsoni Thomas, 1904, from Sudan, which was previously considered a synonym of R. landeri. We reject R. axillaris J. A. Allen, 1917, as a synonym of the R. landeri complex, provisionally regarding it as a valid member of the landeri species group. Finally, we demonstrate that East Africa is home to a fourth species of the landeri complex that is named herein. Final resolution of the systematics of this species complex awaits expanded characterizations (especially of genetics, vocalizations, and noseleaves) and studies of variation in regions of contact.

The genus Ctenomys is represented by 68 species within at least 9 species groups. In Patagonia, there are 11 described species of Ctenomys in 3 phylogenetic species groups: (1) the sociabilis group; (2) the magellanicus group; and (3) the mendocinus group—added to this is C. maulinus, which is not clearly related to any species group. The magellanicus group is the most representative of Patagonia and includes 6 species, several unnamed forms, and has a widespread distribution from Río Negro and Neuquén provinces in the north of Patagonia to Tierra del Fuego province to the south. The magellanicus group is a highly supported clade and comprises 3 geographically defined lineages: the bidaui clade (northern clade) composed of C. bidaui, C. pulcer, and several undescribed forms; the polytypic haigi clade (central clade) comprising C. haigi, C. contrerasi, C. thalesi, C. sericeus, and Ctenomys cf. C. lentulus (sensu Teta and D'Elía 2020); and the monotypic magellanicus clade (southern clade) consisting of haplotypes assigned to C. magellanicus (including C. colburni). Ctenomys magellanicus (Magellanic Tuco-tuco) is widely distributed from southern Santa Cruz province in Argentina and central Aysén in Chile to Isla Grande de Tierra del Fuego in Argentina and Chile. Based on mitochondrial Cytochrome b DNA sequences and morphological assessment (qualitative and quantitative), we describe a new species of Ctenomys related to C. magellanicus from northwestern Chubut Province, Argentina. We provide anatomical comparisons between the new species and other species of Ctenomys from Patagonia, especially C. magellanicus, C. haigi, and C. plebiscitum. In addition, we recognize 2 groupings within C. magellanicus because of their morphometric differences, and report new localities for C. haigi and C. plebiscitum.

El género Ctenomys está formado por 68 especies, las cuales se encuentran agrupadas en, al menos, nueve grupos de especies. Se encuentran descritas 11 especies de Ctenomys para Patagonia, agrupadas en 3 grupos filogenéticos de especies: (1) el grupo sociabilis, (2) el grupo magellanicus y (3) el grupo mendocinus; además de C. maulinus, que no se encuentra relacionado a ningún grupo de especies. El linaje magellanicus es el más representativo en Patagonia, formado por seis especies y varias formas innominadas, ampliamente distribuidas desde las provincias de Río Negro y Neuquén en el norte y hasta y la provincia de Tierra del Fuego en el sur. El grupo magellanicus es un clado con buen soporte y comprende tres linajes geográficamente definidas: el linaje bidaui (clado norte) compuesto por C. bidaui, C. pulcer y formas innominadas; el clado haigi (clado central), es un clado politípico formado por haplotipos asignados a C. haigi, C. contrerasi, C. thalesi, C. sericeus, y haplotipos asignados a Ctenomys cf. C. lentulus (sensu Teta and D'Elía 2020); por último, el clado magellanicus (clado sur) es un clado monotípico formado por C. magellanicus (incluyendo a C. colburni). Ctenomys magellanicus (Tuco-tuco magallánico) está ampliamente distribuido desde el sur de la provincia de Santa Cruz en Argentina y el centro de la Región de Aysén en Chile hasta la Isla Grande de Tierra del Fuego en Argentina y Chile. Sobre la base de secuencias de ADN del citocromo b y análisis morfológicos (cualitativos y cuantitativos), describimos una nueva especie de Ctenomys, relacionada a C. magellanicus, para el noroeste de la provincia del Chubut, Argentina. Además, reconocemos dos agrupaciones dentro de C. magellanicus debido a sus diferencias morfométricas y reportamos nuevas localidades para C. haigi y C. plebiscitum.

Oxymycterus includes 17 species of small- to medium-sized sigmodontine rodents. The taxonomy of this genus has been widely studied, but several unresolved issues persist. One example of this is the Paramo Hocicudo, Oxymycterus paramensis, which over its extended latitudinal range has been associated with several nominal forms that have not been evaluated with an integrative approach. Based on phylogenetic analyses of the Cytb gene, qualitative and quantitative morphological characters, and environmental niche modeling, we reexamined the taxonomic status of the nominal forms akodontius, jacentior, and paramensis while considering the recently recognized species O. willkaurco. The phylogenetic reconstruction guided subsequent analysis of morphological variation and the development of the niche models. Considering the results in an integrative framework, we observed congruence among phylogenetic, species distribution models, and environmental niche models (a proxy indicating different environmental preferences), which support the recognition of 2 species within the concept of O. paramensis s.l. At the same time, we did not observe congruent support for this taxonomic hypothesis from morphological evidence, with the absence of diagnostic qualitative or quantitative characters differentiating the 2 taxa. Considering that some lines of evidence suggest the interruption of gene flow, we see more support for recognizing existing names for 2 taxa at the species level: O. paramensis, endemic to Bolivia; and O. akodontius (which has priority over jacentior), distributed from southern Bolivia to northwestern Argentina. However, we recommend more detailed studies to test the taxonomic scenario advanced here.

Oxymycterus incluye 17 especies de roedores sigmodontinos de tamaño pequeño a mediano. La taxonomía del género ha sido relativamente estudiada, pero aún persisten numerosos problemas taxonómicos sin resolver. Un ejemplo de esto lo constituye el taxón Oxymycterus paramensis, el cual ha sido asociado a varias formas nominales, cuya distinción no se ha evaluado mediante una aproximación integrativa. En este estudio, basándonos en análisis filogenéticos de secuencias del gen Cytb, morfológicos sobre caracteres cualitativos y cuantitativos y de modelado de nicho ambiental y geográfico (pasado y presente), re-examinamos el estatus taxonómico de las formas nominales akodontius, jacentior y paramensis considerando a la especie recientemente descrita O. willkaurco. La reconstrucción filogenética guió los análisis subsecuentes de variación morfológica y el desarrollo de los modelos de nicho. Considerando los resultados en un contexto integrativo, observamos congruencia entre filogenia, modelos de distribución y de nicho ambiental, lo cual apoya el reconocimiento de dos especies dentro del concepto de O. paramensis s.l. Al mismo tiempo, la evidencia morfológica no es congruente con esta hipótesis taxonómica, dado que hay ausencia de caracteres cualitativos diagnósticos y diferenciación morfométrica entre estas especies. Teniendo en cuenta que algunas líneas de evidencia indican la posibilidad de interrupciones de flujo génico, consideramos que existe mayor apoyo para el reconocimiento de dos taxa a nivel de especie, O. paramensis, endémico de Bolivia y O. akodontius (el cual tiene prioridad sobre jacentior), distribuido desde el sur de Bolivia hasta el noroeste de Argentina. Sin embargo, recomendamos que se realicen estudios más detallados para poner a prueba el escenario taxonómico propuesto aquí.

This study investigates acoustic variation of human-audible sonic (below 20 kHz) and human-inaudible ultrasonic (above 20 kHz) calls in a wild subterranean rodent, the Northern Mole Vole (Ellobius talpinus), under 3 call-eliciting tests conducted during captures for 1 day. The Contact-in-Tunnel Test modeled contacts of 2 individuals during digging earth in a burrow tunnel. The Restraint Test modeled restraint of an animal by a surrogate predator (human hand). The Release-to-Burrow Test modeled acoustic communication of many family members returned to their home burrow after their isolation for about 8 h, from morning to evening. We described 8 call types: 3 sonic, 3 ultrasonic, and 2 expanding from sonic to ultrasonic range of frequencies; 6 call types were described for the first time for this species. No relationship was found between acoustic parameters and proxies of body size (body mass and the width of 2 upper incisors). No sex differences were found in body size or the acoustic parameters. Different call types prevailed in different tests: wheeks and upsweeps were made during peaceful interactions; squeaks and squeals were related to animal discomfort during the Restraint Test; rasps were only made in Release-to-Burrow Tests when animals were plugging the burrow entrance; and variative calls did not show any relationship with type of test. Based on presence or absence of certain call types in the tests, we evaluate their potential communicative role in comparison with published data on vocal repertoires of other subterranean rodents.

The daily activity pattern of animals can be classified as diurnal, nocturnal, crepuscular, and cathemeral reflecting strategic decisions to maximize mating and foraging while reducing predation risks and thermal constraints. Among monomorphic mammals, competition for resources and gender-related differences in physiology and reproductive strategies may translate into different activity patterns of males and females. Therefore, to understand the daily activity pattern both aboveground and belowground of the semifossorial rodent Clyomys laticeps, we tested the following hypotheses: (1) males and females differ in their diel activity patterns; (2) males are active for longer periods than females due to a promiscuous mating system and female site fidelity; and (3) higher maximum temperatures restrain C. laticeps activity. The study was carried out in the Serra de Caldas Novas State Park (Goiás, Brazil) in the Cerrado biome. The activity of C. laticeps was recorded using the telemetry technique over 5 days and nights (twice in each season, rainy and dry, between 2019 and 2021). Clyomys laticeps activity was bimodal, with 2 peaks around dawn and dusk, resembling a crepuscular pattern. Temporal segregation in male and female activity patterns was restricted to the dry season, when female activity was more diurnal than males who were mainly nocturnal. Intersexual competition for resources or male-avoidance behavior by females during the dry food scarcity season could contribute to this pattern, although it may also be explained by gender-related differences in thermal tolerances. Overall, males were active for longer periods than females, probably as a strategy to increase mating opportunities among the former and site fidelity in the latter. Finally, temperature imposed major constraints on C. laticeps activities who preferred milder temperatures and avoided being active in temperatures above their thermoneutral zone.

O padrão diário de atividade dos animais pode ser classificado como diurno, noturno, crepuscular e catemeral, refletindo decisões estratégicas para maximizar o acasalamento e busca por alimentos, enquanto reduz os riscos de predação e restrições térmicas. Entre os mamíferos monomórficos, a competição por recursos e as diferenças relacionadas ao gênero na fisiologia e estratégias reprodutivas podem resultar em padrões de atividade distintos entre machos e fêmeas. Portanto, para compreender o padrão diário de atividade, tanto acima quanto abaixo do solo, do roedor semifossorial Clyomys laticeps, testamos as seguintes hipóteses: 1) machos e fêmeas diferem em seus padrões de atividade diurna, 2) machos são ativos por períodos mais longos do que as fêmeas, devido ao sistema de acasalamento promíscuo e à fidelidade das fêmeas ao local do ninho, e 3) temperaturas mais elevadas limitam a atividade de C. laticeps. O estudo foi realizado no Parque Estadual da Serra de Caldas Novas (Goiás, Brasil) no bioma Cerrado. A atividade de C. laticeps foi registrada usando a técnica de telemetria ao longo de 5 dias e noites (duas vezes em cada estação, chuvosa e seca, entre 2019 e 2021). A atividade de Clyomys laticeps foi bimodal, com dois picos ao amanhecer e ao entardecer, assemelhando-se a um padrão crepuscular. A segregação temporal nos padrões de atividade entre machos e fêmeas foi restrita à estação seca, quando a atividade das fêmeas foi mais diurna do que a dos machos, que apresentaram atividade predominantemente noturna. A competição intersexual por recursos ou o comportamento de evitação dos machos pelas fêmeas durante a estação seca, caracterizada pela escassez de alimentos, pode ter contribuído para esse padrão, embora também possa ser explicado por diferenças relacionadas ao gênero nas tolerâncias térmicas. Em geral, os machos foram ativos por períodos mais longos do que as fêmeas, provavelmente como uma estratégia para aumentar as oportunidades de acasalamento entre os primeiros e a fidelidade ao local nas últimas. Finalmente, a temperatura impôs grandes restrições nas atividades de C. laticeps, pois esses roedores preferiam temperaturas mais amenas e evitavam estar ativos em temperaturas acima de sua zona termoneutra.