Mammalian carnivores are often vulnerable to the conversion of natural habitat. Although some species might be frequent in anthropogenic areas, it is not entirely clear how they use modified landscapes, particularly in tropical agroecosystems. Here, we investigated how Puma (Puma concolor) and Maned Wolf (Chrysocyon brachyurus) used three disturbed areas in southeastern Brazil. We sampled 205 camera stations and estimated species occupancy (Ψ) and detection probabilities (p), interpreted as probability of use and frequency of use, respectively. Our models predicted that both species extensively used the study areas (model-averaged probability of use of 0.65 for pumas and 0.50 for maned wolves). Puma frequency of use was higher in stations further from human structures and areas of savanna. Maned Wolf frequency of use was lower in forest-dominated stations and in a more protected and forested study area. Puma probability of use was high in stations closer to watercourses, while Maned Wolf probability of use was higher in unpaved roads and stations farther from human structures. Our findings suggest that pumas and maned wolves may be able to adapt their use of space in agroecosystems featuring riparian corridors and unpaved roads. Nevertheless, our data also reveal possible impacts to carnivore populations in these systems, such as the degradation of riparian environments, road mortality, and human construction avoidance. Thus, some caution is warranted in considering highly modified environments as safe habitats for large carnivores, until further data on the density and vital rates of these species in agricultural-dominated areas have been quantified.

Apesar de serem particularmente vulneráveis à conversão de habitats naturais, mamíferos da ordem Carnivora são frequentemente detectados em áreas antrópicas. Entretanto, ainda não está claro como esses animais utilizam áreas modificadas, especialmente nos agroecossistemas tropicais. Aqui, investigamos como onças pardas (Puma concolor) e lobos-guarás (Chrysocyon brachyurus) usam três áreas modificadas no sudeste do Brasil. Usamos armadilhas fotográficas para amostrar 205 pontos e estimar as probabilidades de ocupação e detecção das espécies – interpretadas como probabilidade de uso (Ψ) e frequência de uso (p), respectivamente. Nossos resultados indicam que ambas as espécies usam extensivamente as áreas de estudo (probabilidade média de uso de 0,65 para a onça e 0,50 para o lobo). A frequência de uso da onça parda é maior em locais distantes de edificações e altamente cobertos por savana. A frequência de uso do lobo-guará é menor em locais dominados por florestas e na área de estudo mais protegida, porém mais florestada. A probabilidade de uso da onça é mais alta próxima aos cursos d'água, enquanto a probabilidade de uso do lobo-guará é maior em estradas não pavimentadas e em locais mais distantes de edificações. No seu conjunto, estas descobertas sugerem que onças pardas e lobos-guarás podem ser capazes de adaptar a sua utilização do espaço em agroecossistemas com corredores ripários e atravessados por estradas não pavimentadas. No entanto, os nossos dados também revelam possíveis impactos para as populações de carnívoros nesses sistemas, tais como a degradação dos ambientes ripários, atropelamentos e mudanças comportamentais para evitar a proximidade com construções humanas. Dessa forma, devemos ser cautelosos ao considerar os ambientes altamente modificados como habitats seguros para os grandes carnívoros, pelo menos até que sejam disponibilizados mais dados sobre a densidade, reprodução e sobrevivência das espécies dentro das áreas dominadas pela agricultura.

Animals with large energy requirements are forced to optimize their hunting strategy, which may result in differentiation of the diet between sexes and across seasons. Here, we examined spatiotemporal variation in the diet of both sexes of the Pond Bat Myotis dasycneme, a species known to have spatial segregation of sexes when the young are born and lactating. Fecal pellets were collected from live animals for a period of 15 years at various locations in the Netherlands. A total of 535 pellets were successfully analyzed by microscopy and an additional 160 pellets by DNA metabarcoding. Morphological and molecular analyses showed that the diet of pregnant and lactating pond bats differed significantly from the diet of females with no reproductive investment. Further analyses of the data showed that pregnant female pond bats are highly dependent on small prey and pupae, mainly nonbiting midges and mosquitoes (Diptera: Chironomidae and Culicidae). These insects can be found in large quantities in peatlands intersected with shallow waterways, the habitat type in which female pond bats were observed more often than males. Our results suggest that during pregnancy the spatial segregation of sexes coincides with sex-specific diets, which might reflect habitat selection based on energy requirements, in addition to lowered intraspecific competition.

Traditionally, researchers have assessed diet selection by comparing consumed versus available taxa. However, taxonomic assignment is probably irrelevant for predators, who likely base their selection on characteristics including prey size, habitat, or behavior. Here, we use an aquatic insectivore, the threatened Pyrenean Desman (Galemys pyrenaicus), as a model species to assess whether biological traits help unravel the criteria driving food and habitat preferences. We reanalyzed data from a previous taxonomy-based study of prey selection in two contrasting streams, one with excellent conservation status and the other affected by diversion for hydropower and forestry. Available and consumed prey were characterized according to nine biological traits, and diet selection was estimated by comparing availability—measured from Surber net samples, and consumption—analyzed by metabarcoding desman feces. Traits offered a biologically coherent image of diet and almost identical selection patterns in both streams, depicting a highly specialized rheophilic predator. Desmans positively selected prey with a preference for fast flow and boulder substrate, indicating their preferred riffle habitat. On the other hand, they positively selected prey with larger but not the largest potential size, living in the water column or the litter, and not inside sediments. They also chose agile prey, swimmers or prey attached to the substrate, prey with high body flexibility, and prey living exposed and clustered in groups. Overall, our results offer a picture of desman diet preference and point to biological traits as being better than taxonomic identity to describe the diet preference of consumers.

Tradicionalmente, los investigadores han estimado la selección de dieta comparando los taxones ingeridos con los disponibles. Sin embargo, la asignación taxonómica probablemente sea irrelevante para los depredadores, que probablemente basan su selección en características tales como el tamaño de presa, su hábitat o su comportamiento. Aquí, utilizamos como especie modelo un insectívoro acuático, el amenazado desmán ibérico (Galemys pyrenaicus), para evaluar si los rasgos biológicos ayudan a desvelar los criterios que rigen las preferencias de alimentos y de hábitat. Reanalizamos los datos de un estudio previo basado en taxonomía sobre la selección de presas de desmán en dos ríos diferentes, uno en excelente estado de conservación y el otro afectado por la derivación de agua para producción de energía hidroeléctrica y por actividades forestales. Se caracterizaron las presas disponibles y consumidas en función de nueve rasgos biológicos y se estimó la selección de dieta comparando la disponibilidad, medida a partir de muestras de redes Surber, y el consumo, determinado mediante metabarcoding de las heces del desmán. Los rasgos biológicos ofrecieron una imagen biológicamente coherente de la dieta y unos patrones de selección casi idénticos en ambos ríos, representando a un depredador reófilo altamente especializado. Los desmanes seleccionaron positivamente las presas con preferencia por corriente rápida y sustrato de bloques, indicando su preferencia de hábitat por los rápidos. Por otro lado, seleccionaron positivamente presas con tamaño potencial grande—pero no el mayor—, que vivían en la columna de agua o en la hojarasca, y no dentro de los sedimentos. También eligieron presas ágiles, presas nadadoras o adheridas al sustrato, presas con alta flexibilidad corporal y presas que viven expuestas y agrupadas. En general, nuestros resultados ofrecen una imagen de las preferencias tróficas del desmán y apuntan a que los rasgos biológicos de las presas describen las preferencias tróficas de los consumidores mejor que su identidad taxonómica.

Mammals are predicted to vary in body size following Bergmann's rule, with individuals found at higher latitudes in colder temperatures being larger in size compared to conspecifics occurring at lower latitudes in warmer temperatures. Body size is similarly expected to vary temporally, with a decrease in size through time due to recent climate warming. While Bergmann's rule is well-supported in mammals, there is increasing evidence of exceptions to the rule. Here, we present patterns of size variation in 17 North American mammal species using five morphological traits (condylobasal skull length, skull width, maxillary toothrow length, body weight, and head-and-body length) to determine if size varies predictably for each species in space and time. We found little support for a widespread Bergmannian pattern for these species at a broad spatial scale (across North America) and a contemporary temporal scale (the past 120 years). The effects of latitude or year on each trait were highly variable with three types of responses: an increase, a decrease, or no change in size across space or through time. Spatial size trends were detected more often than temporal size trends, as the temperature range was significantly larger in space than through time. Body weight (the most variable trait) and head-and-body length were more likely to conform to Bergmann's rule than craniodental measurements. We did not detect any changes in size variability with latitude, and our study species either increased or decreased in size variability over time. Our findings demonstrate that size variation in mammals is highly context-dependent. As such, caution is needed when using rules of body size variation to predict the future response of species to climate warning while valid in theory, it is likely too simplistic of an approach.

Se predice que el tamaño corporal de los mamíferos varía según la regla de Bergmann: los individuos que se encuentran en latitudes más altas con temperaturas más frías son de mayor tamaño que congéneres que se encuentran en latitudes más bajas con temperaturas más cálidas. Del mismo modo, se espera que el tamaño corporal varíe temporalmente, con una disminución del tamaño a lo largo del tiempo debido al calentamiento global en las últimas décadas. Aunque la regla de Bergmann está bien corroborada en mamíferos, cada vez hay más pruebas de excepciones a esta regla. Aquí presentamos patrones en la variación del tamaño de 17 especies de mamíferos norteamericanos utilizando cinco rasgos morfológicos (longitud condilobasal del cráneo, anchura del cráneo, longitud de la hilera dentaria maxilar, peso corporal y longitud de la cabeza y del cuerpo) para determinar si el tamaño varía de forma predecible para cada especie a través del espacio y del tiempo. Encontramos poco apoyo a un patrón Bergmanniano generalizado para estas especies a una escala espacial amplia (en toda Norteamérica) o a una escala temporal contemporánea (los últimos 120 años). Los efectos de la latitud o del año sobre cada rasgo fueron muy variables, pudiendo detectar tres tipos de respuestas: un aumento, una disminución o ningún cambio del tamaño a través del espacio o a lo largo del tiempo. Las tendencias espaciales del tamaño se detectaron con más frecuencia que las temporales, ya que el rango de temperaturas fue significativamente mayor en el ámbito espacial. El peso corporal (el rasgo más variable) y la longitud de la cabeza y del cuerpo se ajustaron más a la regla de Bergmann que las medidas craneodentales. No se detectaron cambios en la variabilidad del tamaño con la latitud, y la variabilidad del tamaño de las especies estudiadas aumentó o disminuyó con el tiempo. Nuestros resultados demuestran que la variación del tamaño en los mamíferos depende en gran medida del contexto. Por ello, hay que ser prudentes al utilizar reglas de variación del tamaño corporal para predecir futuras respuestas de las especies al cambio climático, ya que, aunque válido en teoría, es probablemente un enfoque demasiado simplista.

Assemblages of mammal skeletal remains provide a powerful tool for censusing wildlife populations to establish zoological baselines required for evaluating biogeographic trends over varying timescales. Caves provide an ideal depositional setting to preserve these skeletal remains despite potential time averaging and taphonomic filtering. We describe a Holocene paleontological assemblage from Boomerang Cave in the Bear River Range of Cache County, northern Utah, United States, at an elevation of 2,231 m, and at the boundary between the Great Basin and Rocky Mountain biogeographic provinces. We analyzed 1,228 surface-collected specimens from six areas within the cave, and identified a minimum of 22 nonoverlapping mammalian taxa, comprising all size classes present in the region. Compared to museum records for mammals from the Bear River Range and individuals trapped or observed in the vicinity of the cave, specimen-based rarefaction demonstrates that our assemblage captures most of the mammalian diversity expected in the area. This is particularly apparent for carnivorans and soricids, which are particularly well-represented in the Boomerang Cave assemblage, with the former clade represented by at least nine taxa. This high level of diversity can be attributed to the relatively random nature of natural trap cave deposition, reducing accumulation biases due to size or diet. We also record the first occurrence of Merriam's Shrew (Sorex merriami) from the Bear River Range. Our analysis does not indicate any mammalian changes between late Holocene and present-day communities, but these data establish a new zoological baseline for an alpine community at the interface between two key biogeographic provinces in western North America. Our work highlights the value of collecting skeletal remains from cave assemblages as a convenient and fast method for censusing terrestrial mammalian communities.

For temperate-zone mammals, seasonal changes in weather and food availability often govern energy allocation. In addition, energy allocation strategies usually differ between males and females. Bats are an interesting group in which to evaluate energetic trade-offs as they are highly mobile and lead energetically demanding lives in habitats across a variety of seasonally variable climates. We evaluated year-round changes in body mass and fuel load for three species of bats in northern California: Silver-haired Bat (Lasionycteris noctivagans), California Myotis (Myotis californicus), and Yuma Myotis (Myotis yumanensis). Silver-haired bats are considered migratory species with females likely migrating farther than males. The two species of myotis are considered residents. Body mass of all species peaked in late autumn and was at a minimum during spring. We calculated a fuel load index to normalize size difference between species and sexes. We used sex- and season-specific multiple linear regression models to evaluate rates of change in seasonal fuel loading. Rates of change in fuel load did not differ among species or sexes except for male silver-haired bats that increased fuel loads rapidly during summer. Interspecific comparisons provided valuable insights into the energy allocation and overwintering strategies of these species and are an important initial step toward understanding their ecology over the full annual cycle.

Los cambios estacionales de las condiciones climaticas y de la disponibilidad de alimento a menudo determinan la asignación energética para los mamíferos de zonas templadas. Además, las estrategias de asignación energética suelen diferir entre machos y hembras. El estudio de la asignación energética es desafiante para los murcielagos, en particular para aquellos que no tienen dormideros en áreas conocidas o accesible para el hombre. Los murciélagos constituyen un grupo interesante en el que evaluar las relaciones energéticas coste-beneficio, ya que presentan gran movilidad y llevan vidas de alta demanda energética en una variedad de hábitats con climas variables estacionalmente. Evaluamos los cambios anuales en la masa corporal y carga de grasa de 3 especies de murciélagos en el norte de California: el murciélago canoso (Lasionycteris noctivagans), el murciélago orejas de ratón Californiano (Myotis californicus) y el Yuma myotis (Myotis yumanensis). El murciélago canoso se considera una especie migratoria con las hembras probablemente migrando a distancias mayores que los machos. Las dos especies de myotis se consideran residentes. La masa corporal de todas las especies alcanzó su máximo a finales de otoño y fue mínima durante la primavera. Calculamos un índice de carga de grasa para normalizar la diferencia de tamaño entre especies y sexos. Utilizamos modelos de regresión lineal múltiple específicos por sexo y por estación del año para evaluar las tasas de cambio en la carga de grasa estacional. Las tasas de cambio en la carga de grasa no difirieron entre especies o sexos, excepto para los machos de murciélago canoso, los cuales incrementaron rápidamente la carga de grasa durante el verano. Las comparaciones interespecíficas proporcionaron información valiosa sobre la alocación energética y las estrategias de invernada de estas especies y representan un paso inicial importante para comprender su ecología durante el ciclo anual completo.

The Eastern Small-footed Bat (Myotis leibii) inhabits mountainous areas of the eastern United States and generally roosts in cliff faces and talus slopes. However, the difficulty of accessing these sites has limited research on this species. We studied survival rates of eastern small-footed bats by capturing bats roosting in crevices between sections of concrete guardrails on bridges in the Ozark mountains of northern Arkansas from 2014 to 2021. We accumulated 1,413 bat captures (1,050F; 363M) of 283 individual females and 198 individual males sampled over 8 years and determined apparent annual survival of female bats using Cormack–Jolly–Seber survival models. Only 1 of 30 bats tested positive for the presence of Pseduogymnoascus destructans, a fungus causing white-nose syndrome (WNS) which is responsible for significant declines in populations of some North American bat species, when all maternity colonies were sampled in the spring of 2019. Overall apparent annual survival of all females was 0.643, with first-year juvenile survival of 0.472 and adult (ages 1–6) survival of 0.744, approximately 58% greater than first-year survival. Apparent annual survival did not differ greatly among the sites or among years. We found no significant decline or increase in overall number of bats among all sites during the 8 years of study. Stability in both the number of bats encountered and their survival rates suggests that the impact of WNS on these colonies has been marginal.

Due to the vulnerability of neonatal ungulates, selection of a birth site can have important implications for offspring survival and thus fitness of the mother. We studied parturition site selection in cow Elk in southeastern Kentucky, United States, using a use–availability framework to evaluate the effects of landscape variables sampled at multiple spatial grains on the relative probability of use of parturition sites. We identified 81 Elk parturition sites during May–Aug 2020–2022 and fit several candidate resource selection function models using a sample of 24,314 random locations to characterize habitat availability. Using an information-theoretic approach to rank candidate models, we identified two top-performing models (cumulative ωi = 0.97), which indicated that at fine spatial grains (∼10- and 30-m pixels) parturient cow Elk selected for intermediate canopy cover and lower terrain ruggedness compared to available locations. At coarse grains (250–1,000-m buffers/neighborhoods), Elk selected against vegetation greenness/biomass, for higher topographic positions, for closer proximity to major roads, and with higher solar radiation potential. We also found evidence that Elk responded positively to forest/open edge densities at coarse grains, demonstrating that calving habitat throughout the Kentucky Elk Restoration Zone is associated with heterogeneous landscapes resulting from surface mine reclamation. As a result, habitat management actions should aim to increase patchy, early successional shrub cover on gentle topography.

Many carnivore populations have experienced substantial declines and are at increased risk of extinction, mainly due to negative interactions with humans and biological traits that make them susceptible to habitat loss and fragmentation, often driven by agricultural expansion. Carnivore community richness is likely influenced by many direct and indirect factors, though it is unclear how carnivore communities are structured in prairie landscapes that are considered one of the most imperiled ecosystems worldwide. Our goal was to identify landscape-scale effects driving carnivore community richness in a contemporary agro-prairie ecosystem. We used 3 years of presence data (2018–2020) from camera-trap sites (n = 381) distributed across western Kansas, United States and developed a structural equation model (SEM) to test a priori hypotheses explaining carnivore richness. Measures of water availability, native prairie, and agriculture—as well as sampling effort (i.e., days cameras were active)—were all positively associated with carnivore richness. Additionally, our index of rabbit abundances at sites had a direct positive effect on our measure of carnivore richness. Our SEM explained 42% of the variance in carnivore richness (χ² = 8.76, d.f. = 21, P = 0.99) in this human-dominated landscape. Our results suggest that carnivore communities in agro-prairie landscapes are structured through multiple direct and indirect landscape-scale pathways. Contemporary agro-prairie mosaics may act as filters for the agricultural tolerance of carnivores, with species more vulnerable to native prairie loss becoming locally extirpated.

Muchas poblaciones de carnívoros han disminuido sustancialmente y corren un mayor riesgo de extinción, principalmente debido a las interacciones negativas con humanos y sus propias características biológicas que las hacen susceptibles a la pérdida y fragmentación del hábitat. La pérdida y fragmentación del hábitat se debe en gran medida a la expansión agrícola en muchas regiones, representando una amenaza significativa para la persistencia de carnívoros. La riqueza de la comunidad carnívora está influenciada probablemente por muchos factores directos e indirectos, aunque no está claro cómo se estructuran las comunidades carnívoras dentro de los paisajes de pastizales, ecosistemas considerados de los más amenazados en el mundo. Nuestro objetivo es identificar efectos a escala del paisaje que impulsan la riqueza de la comunidad carnívora dentro de un ecosistema agro-pastizal contemporáneo. Utilizamos datos de presencia de tres años (2018–2020) en estaciones de cámaras trampa (n = 381) distribuidos a través del oeste de Kansas, EE. UU. y desarrollamos un modelo de ecuación estructural (SEM) para probar una hipótesis a priori que explique la riqueza de carnívoros. La disponibilidad de agua, el pastizal nativo y la agricultura, tanto como el esfuerzo de muestreo (es decir, los días en que las cámaras estuvieron activas), se asociaron positivamente con la riqueza de carnívoros. Además, nuestro índice de abundancia de lagomorfos en nuestro sitio agro-pastizal contemporáneo tuvo un efecto positivo directo con la riqueza de carnívoros. Nuestro SEM explicó el 42% de la variación en la riqueza de carnívoros (χ² = 8.76, d.f. = 21, P = 0.99) en este paisaje dominado por humanos. Nuestros resultados sugieren que las comunidades de carnívoros en paisajes agro-pastizal están estructuradas a través de múltiples vías directas e indirectas a escala de paisaje. Los mosaicos agro-pastizales contemporáneos podrían actuar como filtros para la tolerancia agrícola de los carnívoros, con especies más vulnerables a la pérdida de pastizales nativas extirpadas localmente.

Environmental and climatic variation drive animal migration. Animals must adjust their behavioral strategies, for example, habitat selection, to match best variation in resources whose value likely varies with conditions such as weather. For example, climate change makes processes such as snowmelt and the emergence of vegetation less predictable at the scale of months or weeks. Furthermore, climate change makes meteorological conditions unpredictable—or dynamic—at the scale of days and hours. The profitability of selecting any particular resource may vary according to local meteorological condition. We studied the impact of dynamic weather conditions on fine-scale movement strategies and resource selection during spring migration of adult female Woodland Caribou (Rangifer tarandus). We assessed the role played by static resources such as open, lichen, and closed forest habitats and their role in a context-dependent of dynamic weather conditions, including temperature, precipitation, and changing snow water equivalent. We tested the role of static resources and dynamic conditions in three contexts: (1) whether caribou were encamped or moving using hidden Markov models; state-specific habitat selection for, and the interaction between, resources and conditions while (2) encamped and (3) moving. Weather conditions influenced the probability of moving or staying encamped, and the probability of selecting for a resource, which likely reflects the profitability of a given resource in a particular condition. The probability of staying encamped in the forest increases as temperature increases, and the probability of selecting an open area is higher when precipitation is lower. We highlight how meteorological conditions modify the selection of a static resource and likely the profitability of a given resource. The resource utility to a consumer is increasingly susceptible to climate change-induced effects.

Large carnivores strongly shape ecological interactions within their respective ecosystems, but experience significant conflicts with humans across their range due to their specific ecological resource requirements. The Tiger (Panthera tigris) typifies the challenges faced by large carnivore species globally. India retains the majority of the global Tiger population with a substantial number occurring outside protected areas where they are prone to conflict through livestock predation and injury or death to people and Tigers. Tiger food habits was investigated across the Indian part of the Terai-Arc Landscape (TAL), a globally important Tiger conservation landscape, to understand Tiger prey selection patterns and hotspots of livestock predation-related conflict. 510 genetically confirmed Tiger feces were collected across the landscape and 10 wild ungulates and livestock as prey species were identified. Large-bodied species (Sambar, Swamp Deer, Nilgai, Chital, Wild Pig, and livestock) comprised ∼94% of the diet, with Sambar, Chital, and livestock having the highest relative proportions. Habitat-specific (Shivalik-Bhabar and Terai) analyses indicate that prey selection is driven by prey abundance and body weight but not determined by protection status (protected areas vs non-protected areas). Results also suggest that PAs and non-PAs in the Terai region were more prone to livestock predation-related conflict. Careful management interventions with community involvement should be utilized to reduce such threats. In this study, we suggest long-term conservation plans including prey abundance estimation outside PAs, reduction of grazing pressures, and detailed records of Tiger mortalities with causal investigations to ensure future conflict-free Tiger persistence across TAL.

As global large carnivore populations continue to decline due to human actions, maintaining viable populations beyond protected area (PA) borders is critical. African lions (Panthera leo) ranging beyond PA borders regularly prey on domestic livestock causing humans to retaliate or even preemptively kill lions to minimize impacts of lost livestock. To understand how lions navigate high-conflict areas in human-dominated landscapes, lions were observed and monitored in the eastern Panhandle of the Okavango Delta between October 2014 and December 2016, and five lions were fitted with GPS satellite collars from August 2015 to December 2016. Lion prides and coalitions were small, with all prides having four or fewer females and all coalitions having two or fewer males. Home range size varied between the sexes but was not statistically different (males: x̄ = 584 km², n = 3; females: x̄ = 319 km², n = 2). There was considerable spatial overlap in home ranges as nonassociating, neighboring collared individuals utilized high levels of shared space (female–female overlap = 152 km², representing 41–56% of respective home ranges; male–male overlap = 125–132 km², representing 16–31% of respective home ranges). However, neighboring lions varied use of shared space temporally as evidenced by low coefficients of association (< 0.08), avoiding potentially costly interactions with neighboring individuals. Highest levels of overlap occurred during the wet and early dry seasons when flood waters minimized the amount of available land area. All collared individuals minimized time in close proximity (< 3 km) to human habitation, but some individuals were able to rely heavily on areas where unmonitored livestock grazed. While most lions exist within PAs, anthropogenic impacts beyond PA boundaries can impact critical populations within PAs. Studying systems beyond park boundaries with high levels of human–lion conflict while also establishing conservation programs that account for both ecological and sociocultural dimensions will better aid lion conservation efforts moving forward.

The reintroduced population of Mexican gray wolves (Canis lupus baileyi) continues to rely on a carefully managed captive breeding program. Although success of that program depends on detailed knowledge of reproductive processes, age of puberty has not been determined. This study assessed male puberty status (presence of sperm in ejaculates), maintained in nine US facilities, during their first breeding season. Variables possibly associated with puberty were also evaluated. There was a significant effect of body weight, testis size, facility latitude, and date of collection, whereas a statistical trend was found for age and inbreeding coefficient. Social factors, including being housed with sire, had no effect. Over half the males in their first breeding season were producing sperm, although in some cases sperm quality was poor, suggesting possible infertility. Although there was no minimum body weight associated with presence of sperm, likelihood increased with increasing body weight, highlighting a possible critical role for nutrition. The trend for sperm production in males collected later in the breeding season and at lower latitudes suggests that later collections, especially at higher latitudes, might reveal a higher percentage of pubertal males. These results have potential implications for breeding program management and introduce the possibility that more wild gray wolves than previously thought might produce sperm during their first year, even if they do not sire young.

La población reintroducida de lobo mexicano (Canis lupus baileyi) depende aún de un programa de reproducción en cautiverio cuidadosamente gestionado. Aunque el éxito del programa depende del conocimiento detallado de los procesos reproductivos, la edad de la pubertad no ha sido determinada. Este estudio evaluó el estado de pubertad de los machos (presencia de espermatozoides en los eyaculados) mantenidos en nueve instituciones de los Estado Unidos, durante su primera temporada reproductiva. También se evaluaron variables asociadas posiblemente con la pubertad. Se encontró un efecto significativo del peso corporal, el tamaño de los testículos, la latitud de la institución y la fecha de recolección; mientras que para la edad y el coeficiente de consanguinidad se encontró una tendencia estadística. Factores sociales, incluyendo estar alojado con el padre, no tuvieron ningún efecto. Más de la mitad de los machos en su primera temporada reproductiva produjeron espermatozoides, aunque en algunos casos la calidad era deficiente, lo que sugiere una posible infertilidad. Aunque no hubo un peso corporal mínimo asociado con la presencia de espermatozoides, la probabilidad aumentó con el aumento del peso corporal, destacando el posible papel crítico de la nutrición. La tendencia de producción de espermatozoides en los machos recolectados en fechas posteriores en la temporada de reproducción y en latitudes más bajas, sugiere que recolecciones más tardías, especialmente en latitudes más altas, podrían revelar un mayor porcentaje de machos púberes. Estos resultados tienen implicaciones potenciales en la gestión del programa de reproducción e abren la posibilidad de que más lobos grises silvestres puedan producir espermatozoides durante su primer año de lo que se pensaba anteriormente, incluso si no producen crías.

The Coyote (Canis latrans) is one of the most studied species in North America with at least 445 papers on its diet alone. While this research has yielded excellent reviews of what coyotes eat, it has been inadequate to draw deeper conclusions because no synthesis to date has considered prey availability. We accounted for prey availability by investigating the prey selection of coyotes across its distribution using the traditional Jacobs' index method, as well as the new iterative preference averaging (IPA) method on scats and biomass. We found that coyotes selected for Dall's Sheep (Ovis dalli), White-tailed Deer (Odocoileus virginianus), Eastern Cottontail Rabbit (Sylvilagus floridanus), and California Vole (Microtus californicus), which yielded a predator-to-preferred prey mass ratio of 1:2. We also found that coyotes avoided preying on other small mammals, including carnivorans and arboreal species. There was strong concordance between the traditional and IPA method on scats, but this pattern was weakened when biomass was considered. General linear models revealed that coyotes preferred to prey upon larger species that were riskier to hunt, reflecting their ability to hunt in groups, and were least likely to hunt solitary species. Coyotes increasingly selected Mule Deer (O. hemionus) and Snowshoe Hare (Lepus americanus) at higher latitudes, whereas Black-tailed Jackrabbit (L. californicus) were increasingly selected toward the tropics. Mule Deer were increasingly selected at higher coyote densities, while Black-tailed Jackrabbit were increasingly avoided at higher coyote densities. Coyote predation could constrain the realized niche of prey species at the distributional limits of the predator through their increased efficiency of predation reflected in increased prey selection values. These results are integral to improved understandings of Coyote ecology and can inform predictive analyses allowing for spatial variation, which ultimately will lead to better understandings about the ecological role of the coyote across different ecosystems.

El coyote (Canis latrans) es una de las especies más estudiadas en América del Norte con al menos 445 artículos solo sobre su dieta. Si bien esta investigación ha producido excelentes revisiones de lo que comen los coyotes, no ha sido adecuada para sacar conclusiones más profundas porque ninguna síntesis hasta la fecha ha considerado la disponibilidad de presas. Tomamos en cuenta la disponibilidad de presas al investigar la selección de presas de los coyotes a lo largo de la distribución de la especie utilizando el método tradicional del índice de Jacobs, así como el nuevo método iterativo de promedio de preferencia sobre excrementos y biomasa. Descubrimos que los coyotes seleccionados para la oveja de Dall (Ovis dalli), el venado de cola blanca (Odocoileus virginianus), los conejos de rabo blanco del este (Sylvilagus floridanus) y los campañoles de California (Microtus californicus), produjeron una proporción de masa de depredador a presa preferida de 1:2. También encontramos que los coyotes evitaban depredar a otros mamíferos pequeños, incluidos los carnívoros y las especies arbóreas. Hubo una fuerte concordancia entre el método de promedio de preferencia tradicional e iterativo en los excrementos, pero este patrón se debilitó cuando se consideró la biomasa. Los modelos lineales generales revelaron que los coyotes preferían cazar especies más grandes que eran más riesgosas de cazar, lo que reflejaba su capacidad para cazar en grupos, y era menos probable que cazaran especies solitarias. Los coyotes seleccionaron cada vez más al venado bura (O. hemionus) y la liebre con raquetas de nieve (Lepus americanus) en latitudes más altas, mientras que la liebre de cola negra (L. californicus) fue seleccionada cada vez más hacia los trópicos. El venado bura se seleccionaba cada vez más en densidades más altas de coyotes, mientras que la liebre de cola negra se evitaba cada vez más en densidades más altas de coyotes. La depredación de los coyotes podría restringir el nicho realizado de las especies de presa en los límites de distribución de las especies de depredadores a través de su mayor eficiencia de depredación reflejada en mayores valores de selección de presas. Estos resultados son parte integral de una mejor comprensión de la ecología del coyote y pueden informar análisis predictivos que permitan la variación espacial, lo que en última instancia conducirá a una mejor comprensión sobre el papel ecológico del coyote en diferentes ecosistemas.

The size of the home range of a mammal is affected by numerous factors. However, in the normally solitary, but polygynous, Leopard (Panthera pardus), home range size and maintenance is complicated by their transitory social grouping behavior, which is dependent on life history stage and/or reproductive status. In addition, the necessity to avoid competition with conspecifics and other large predators (including humans) also impacts upon home range size. We used movement data from 31 sites across Africa, comprising 147 individuals (67 males and 80 females) to estimate the home range sizes of leopards. We found that leopards with larger home ranges, and in areas with more vegetation, spent longer being active and generally traveled faster, and in straighter lines, than leopards with smaller home ranges. We suggest that a combination of bottom-up (i.e., preferred prey availability), top-down (i.e., competition with conspecifics), and reproductive (i.e., access to mates) factors likely drive the variability in Leopard home range sizes across Africa. However, the maintenance of a large home range is energetically expensive for leopards, likely resulting in a complex evolutionary trade-off between the satisfaction of basic requirements and preventing potentially dangerous encounters with conspecifics, other predators, and people.

Functional traits are phenotypic characteristics that contribute to fitness of individuals in dynamic and changing environments. In mammals, both categorical and continuous (e.g., quantitative) functional traits have been extensively utilized as proxies for diet, locomotion, and other aspects of species ecology, but there has been less focus on form and function of soft tissues. This is particularly true for the digestive system, which varies in size and complexity across Class Mammalia and plays a major role in the energetics of species. To guide more effective utilization of gastrointestinal (GI) morphology as a functional proxy in small mammal ecology, we examined how GI tracts (lengths and masses of four GI sections) varied within a population of deer mice (Peromyscus maniculatus) in the Southern Appalachian Mountains of North Carolina, United States. We collected samples of adult P. maniculatus monthly for 1 year and measured GI tracts to quantify variation with respect to seasonality and trophic level, providing insight into plasticity in this soft tissue trait over time. We found that season had a significant effect on the total length and wet mass of the GI tract, with January mice having the longest GI tracts and lengths being shortest in the summer. The relative shortening of the GI tract in summer corresponded with a partial trophic increase detected by stable isotope signatures. GI length and wet mass also were affected by reproduction, but males and females responded in sex-specific ways to demands of reproduction, with reproductively active males having shorter and lighter GI tracts than nonreproductively active males. Our study provides proof-of-concept for understanding population-level plasticity in a rarely collected soft tissue trait, which may also be complementary to standard craniodental measurements as a functional dietary proxy to understand mammalian ecology and community assembly.

Los rasgos funcionales son características fenotípicas que contribuyen a la aptitud de los individuos en entornos dinámicos y cambiantes. En los mamíferos, los rasgos funcionales categóricos y continuos (por ejemplo, cuantitativos) se han utilizado ampliamente como indicadores de la dieta, la locomoción y otros aspectos de la ecología de las especies, a la vez que se ha prestado menos atención a la forma y función de los tejidos blandos. Este es particularmente el caso del sistema digestivo, que varía en tamaño y complejidad a través de la Clase Mammalia, jugando un papel importante en la energética de las especies. Para propiciar una utilización más efectiva de la morfología gastrointestinal (GI) como un rasgo funcional en la ecología de los pequeños mamíferos, examinamos cómo los tractos GIs (longitudes y masas de cuatro secciones GI) variaban dentro de una población de ratones ciervos (Peromyscus maniculatus) de las Montañas Apalaches del sur de Carolina del Norte, Estados Unidos. Mensualmente, durante un año, recolectamos especímenes adultos de P. maniculatus y medimos sus tractos gastrointestinales para cuantificar la variación con respecto a la estacionalidad y el nivel trófico, brindando información sobre la plasticidad en estos rasgos de tejido blando a lo largo del tiempo. Descubrimos que la estacionalidad tiene un efecto significativo en la longitud total y la masa húmeda del tracto gastrointestinal, ya que los ratones de enero tienen los tractos gastrointestinales más largos y las longitudes son más cortas durante el verano. El acortamiento relativo del tracto GI en verano se correspondió con un aumento trófico parcial detectado por las cuantificación de isótopos estables. La longitud GI y la masa húmeda también se vieron afectadas por la reproducción; pero los machos y las hembras respondieron de manera diferente a las demandas de la reproducción. Los machos reproductivamente activos tienen tractos gastrointestinales más cortos y ligeros que los machos no activos reproductivamente. Nuestro estudio constituye un avance para comprender la plasticidad a nivel de población en un rasgo de tejido blando raramente recolectado, que también puede ser complementario a las mediciones craneodentales estándar como un proxy dietético funcional para entender la ecología de los mamíferos y el ensamblaje de la comunidad.

Among burrowing rodents, forelimb morphology frequently shares an intricate relationship with soil substrates. Soils vary widely in texture and density, leading to differences in friability (e.g., the relative ability of particles to be broken apart), which often requires forelimb specializations in digging animals. Kangaroo rats (Dipodomys spp.) dig and occupy burrows, a trait that is essential to their survival. Some Dipodomys species are restricted to particular substrates that presumably require species-specific forelimb traits. Here we examined the forelimb morphology and soil substrates inhabited by range-restricted and widely ranging Dipodomys species to explore the variation in soil usage, forelimb specializations, and the relationship between these traits. We assessed size and shape traits of preserved specimen forelimb bones using traditional and geometric morphometric techniques and extracted soil data associated with the collecting locality of each specimen. We expected species that inhabit dense soil substrates to display specialized forelimb morphology typified by an elongated scapula and robust humerus, radius, and ulna. The species differed substantially in their soil associations and forelimb morphologies. In particular, forelimb traits that enhance mechanical digging ability were detected in D. elator, a range-restricted species that inhabits dense clay-rich soils. These findings suggest that Dipodomys species that inhabit dense substrates may require correspondingly specialized forelimb morphology and that these traits may limit the desirable geographic ranges inhabited by these species. This may provide important information when making conservation decisions given that unlike other habitat features, soil substrates cannot be easily modified to suit the needs of the organism.

In this study, we analyze and compare the genetic structure of edible dormice representing five populations, inhabiting forest complexes in southwestern Poland that differ in their degree of fragmentation and isolation. Total genomic DNA was isolated from hairs with bulbs of 145 individuals captured between 2018 and 2020. All dormice sampled were genotyped at 14 microsatellite loci. Population genetic analyses showed that genetic variability in the studied dormice, assessed based on observed and expected heterozygosity as well as allelic richness, was on average very low (0.39, 0.43, and 2.83, respectively). In the populations studied, genetic structure was detected indicating two or five distinct genetic clusters, the existence of which can be attributed to either historical factors or modern human activity. Genetic differentiation between dormice living in the studied localities, determined by F_ST, ranged from 0.07 to 0.40 (all F_ST coefficients were significant at P < 0.05). A significant positive correlation was detected between genetic differentiation and geographic distance (r = 0.645, P < 0.017), indicating that genetic differentiation increases with distance, but no correlation between genetic differentiation and habitat barriers (r = 0.359, P < 0.132). The results of this research are compared to those of other European populations of edible dormice, and implications for the future of this endangered species are discussed.

Understanding habitat selection is fundamental to addressing the response of a species to disturbance. Because resources are unevenly distributed across the landscape, habitat selection occurs at multiple scales. We used capture–mark–recapture and radiotelemetry techniques to quantify the macrohabitat and microhabitat associations that define space use of the Southern Red-backed Vole (Myodes gapperi) in northeastern forests. Macrohabitat characteristics were evaluated at the scale of the forest stand by comparing conditions between visited and unvisited trap stations and suggest red-backed voles have an affinity for locations with higher basal area of Eastern Hemlock (Tsuga canadensis) and more coarse woody material. For microhabitat characteristics we modeled the influence of forest structure, ground cover, and geographic features on home range, specifically core area placement. We found that Southern Red-backed Vole core areas were associated with higher Red Maple (Acer rubrum) basal area, deeper leaf litter, greater density of hemlock stems, and closer proximity to water. The affinity of southern red-backed voles for eastern hemlock raises questions about population persistence and shifts in distribution as eastern hemlock stands are replaced by hardwood stands following infestation by Hemlock Woolly Adelgid.

Play is an important component of development in a range of mammalian species, and may provide adaptive benefits for young individuals in some cases. We evaluated the hypothesis that social play in juvenile Belding's ground squirrels (Urocitellus beldingi) promotes development of cautious responses when individuals are confronted with a potential threat. We observed the play behavior of juvenile U. beldingi across the developmental period in which play primarily occurs. To measure caution, we conducted behavioral tests on individual squirrels at the beginning and toward the end of the play period, and again when the individuals were yearlings. During tests we recorded the distances at which squirrels first noticed and fled from a human intruder. In initial tests, juveniles with yearling mothers responded to intruders at greater distances than did juveniles with older mothers suggesting maternal effects on the development of caution. Distances at which juveniles noticed and fled from an intruder increased across the play interval, suggesting increased caution to a potential threat as early development progresses. Social play was a reliable predictor of increases in caution, with juveniles who engaged in social play at higher rates having greater increases in the distance to notice and flee from an intruder. Distances to flee from an intruder at the end of the play interval were reliable predictors of distances to flee from an intruder as a yearling, suggesting consistency in cautious responses among individual U. beldingi over time. Rates of social play as a juvenile were reliable predictors of distances to notice and flee from an intruder as a yearling, suggesting that possible influences of play behavior on cautious responses extend beyond the juvenile period.

Rodents are notable for their unique life history traits that render a fast-breeding capacity. Their short generation times allow local adaptations to appear, and several studies have tried to understand if—and how—geographical variables influence local adaptation in life history traits. We compared demographic and life history traits of the Neotropical cricetid Necromys lasiurus based on 7,400 museum specimens collected daily and simultaneously over 5 years at several sites in the Caatinga biogeographic domain subject to heterogeneous geographic and climatological variables. This sample, assembled by the National Plague Service between 1951 and 1955, includes skulls, skins, and individual specimen data currently deposited in the Museu Nacional (Rio de Janeiro, Brazil). Based on this material, we analyzed population fluctuation, breeding season, sexual size dimorphism, sexual maturity, and litter size. We also hypothesized that geographic variables (elevation, rainfall, temperature, longitude, and latitude) influence key life history traits, such as size at birth and litter size. Overall, N. lasiurus showed plastic reproductive patterns, with few traits shared among populations. Notably, there is strong seasonal variation in population fluctuation patterns, breeding events clumped in early dry season and old individuals distributed throughout all the year, as has been seen for populations in other biomes. Geography had no influence on size at birth but litter size was explained by the interaction between maternal weight and geographical variables. Plastic life history traits so intimately responsive to climatological variables likely contribute to N. lasiurus having one of the largest geographic ranges among Neotropical cricetids, as well as to its status as the most important plague reservoir in the Caatinga domain.

Roedores são notáveis por suas características de história de vida únicas que conferem uma capacidade de reprodução rápida. Suas gerações curtas permitem que as adaptações locais apareçam, e vários trabalhos ten-tam entender se—e como—variáveis geográficas influenciam a adaptação local na história de vida. Para tanto, comparamos características da história de vida e demografia do roedor cricetídeo neotropical Necromys lasiurus com base em 7.400 espécimes de museu coletados diária- e simultaneamente em vários locais da Caatinga brasileira ao longo de cinco anos (1951–1955) em localidades sob variáveis geográficas e climatológicas bastante heterogêneas. Esta amostra, reunida pelo Serviço Nacional de Peste, inclui crânios e peles e os respectivos dados individuais depositados no Museu Nacional (Rio de Janeiro, Brasil). Com base nesse material, analisamos a flutuação populacional, o período reprodutivo, o dimorfismo sexual em tamanho, a maturidade sexual e o tamanho de prole. Além disso, testamos a hipótese de que as variáveis geográficas (altitude, chuva, temperatura, latitude e longitude) influenciam características-chave da história de vida, como o tamanho ao nascer e tamanho da prole. Em geral, N. lasiurus apresenta padrões reprodutivos muito plásticos, com poucas características compartilhadas entre as populações. Todavia, há forte variação sazonal na flutuação populacional, com eventos reprodutivos concentrados na estação secae indivíduos velhos distribuídos ao longo de todo o ano, aspectos já observados em populações de outros biomas. As variáveis geográficas não influenciam no tamanho do indivíduo ao nascer. No entanto, de acordo com nossas previsões, o tamanho da prole foi explicado pela interação entre o peso da mãe e variáveis geográficas. Características plásticas da história de vida tão intimamente relacionadas às variáveis climatológicas provavelmente contribuem para N. lasiurus apresentar uma das distribuições geográficas mais amplas entre cricetideos Neotropicais, bem como para o importante status dessa espécie como reservatório de zoonoses na Caatinga.

Social mating systems (e.g., monogamy, polygamy, or polyandry) are relatively stable behavioral strategies developed by environmental in animals, but the genetic imprint of a particular mating system is often incongruent with the social mating system due to extrapair matings. However, the genetics of mating systems remain little understood in rodents. In this study, we investigated the genetic signature of the mating system of 141 (63 females, 78 males) field-captured midday gerbils (Meriones meridianus)—a rodent species commonly found in the Minqin Desert in China—through microsatellite site analyses of genetic structure and relatedness. Seven pairs of highly polymorphic microsatellite loci were selected and were highly polymorphic, with the combined exclusion probability greater than 0.99. The parent pair paternity test by Cervus 3.0 software show that 11 mother–offspring and nine father–offspring relationships were identified in 2018, involving 26 individuals from 10 families. Similarly, 19 mother–offspring and 19 father–offspring relationships were identified in 2019, involving 48 individuals from 18 families. All three types of genetic mating structure were identified—monogamy (19 families), polyandry (4 families), and polygyny (5 families), providing evidence that the genetics underlying mating systems in this species are variable, can be incongruent with behavioral evidence for social mating systems, and could vary based on environmental cues, including degree of perceived or actual predation.

婚配制度(如单配制、一雄多雌制或一雌多雄制)是动物在特定环境和遗传因素条件下形成的相对稳定的繁殖策略，但由于配偶外交配，遗传性婚配制度往往与社会婚配制度不一致。然而，在啮齿类动物中，遗传性婚配制度仍旧研究较少。在本研究中，我们利用多态性分子微卫星位点探究了野外捕获的141只(雌性63只，雄性78只)子午沙鼠(Meriones meridianus)的遗传结构和亲缘关系，子午沙鼠是中国民勤沙漠中常见的一种啮齿动物。本研究共筛选出7对高多态性微卫星位点,综合排除概率大于0.99。通过Cervus 3.0软件进行亲缘关系分析，结果表明2018年捕获的个体中，有11对母子关系和9对父子关系，涉及10个家群的26只沙鼠。与2018年结果相似，2019捕获个体中，有19对母子关系和19对父子关系，涉及18个家群的48只沙鼠。综上子午沙鼠野外群体研究表明，遗传性婚配制度有单配制(19个家群)、一雌多雄制(4个家群)和一雄多雌制(5个家群)。

Urban environments are novel alternative habitats for wildlife. Anthropogenic food resources such as supplemental feeding (SF) are usually abundant, stable across seasons, and sometimes rich in calories. Although anthropogenic food resources could modify the seasonality and composition of the diets of urban animals, previous studies have been limited to qualitative assessments based on stomach content and food remains. Our study compared diet seasonality and niche width between rural and urban populations of Eurasian red squirrels (Sciurus vulgaris) in Hokkaido, Japan, using direct observation and stable isotope analysis. We found that dietary seasonality was lower in urban populations than in rural populations. The frequency of seed use was higher throughout the year in urban populations than in rural populations, possibly because of excessive seeds by SF in urban squirrels. Additionally, female body weights of the urban population were higher than those of the rural population. However, this was not true for males. Because high body weight can increase reproductive success in females, it is feasible that diet modification could contribute to population growth in urban squirrels. However, no differences in male body weight were observed, possibly due to energy loss caused by intense male–male competition at feeding sites. Our study highlights the importance of studying the multidimensional effects of anthropogenic foods on wildlife.

Asiatic short-tailed shrews (Blarinella and Parablarinella) are small insectivorous mammals distributed mainly in central and southwestern China, and adjacent Myanmar and Vietnam, currently comprising three species. In 2021, we collected five specimens of Asiatic short-tailed shrews in the Dabie Mountains, eastern China, which is geographically distant from the known distribution of the taxa. Herein, we integrated molecular and morphometric approaches to assess the taxonomy, phylogeny, and divergence of Asiatic short-tailed shrews. Our results indicate that the specimens collected from Dabie Mountains represent a new species, formally described here. The new species is morphologically distinguishable from other Asiatic short-tailed shrews by the combination of a triangular upper P⁴, lighter feet color, relatively broader skull, and more curved outline of tooth row of P⁴–M³. Phylogenetic analyses indicate the new species is sister to P. griselda, and the p-distance of Cyt b between the two species is 8.3%. The divergence between the new species and P. griselda occurred ca. 3.08 million years ago and may have been affected by East Asia's topographic and climate changes in the late Pliocene.