Temporal activity patterns of animals can indicate how individuals respond to changing conditions. Gregarious roosting bats provide an opportunity to compare activity patterns among individuals living in the same location to investigate how reproductive status or sex may influence activity budgets. We examined how the activity patterns of the nectarivorous bat Leptonycteris yerbabuenae vary depending on reproductive conditions, sex, and environmental conditions. We analyzed 5 years of individual mark-resighting data using daily detections of L. yerbabuenae marked with passive integrated transponder tags (PIT-tags) at 3 subterranean roosts on the Baja California Peninsula, Mexico. We derived 4 metrics using PIT-tag detections at roost entrances to calculate periods inside the roost and time spent outside the roost (time of emergence, returns to the roost, hours inside the roost, and hours of activity). We found differences among pregnant, lactating, and nonreproductive females for roost returns, hours inside the roost, and hours of activity outside the roost. Lactating females spent the longest time outside the roost, suggesting that the energetic demands of lactation require longer foraging bouts. Contrary to our expectations, lactating females had the fewest returns to the roost during the night, suggesting that lactating females did not shorten foraging bouts to return to nurse pups. Activity patterns differed between females and males and among seasons associated with different food availability. Females had fewer returns during the night and spent more time outside the roost than males. The time of emergence for males was earlier than for females except during the nectar season when most females are reproductively active. Differences in activity patterns among reproductive status, sex, and environmental conditions show how individuals modify behaviors to meet their energetic demands. We demonstrate how mark-resighting data from PIT-tag systems at roost entrances can be used to compare activity patterns of gregarious roosting bats.

Los patrones temporales de actividad de los animales pueden indicar cómo responden los individuos a condiciones cambiantes. Los murciélagos que forman agregaciones en refugios brindan la oportunidad de comparar patrones de actividad entre individuos que viven en el mismo sitio, con el fin de investigar cómo influye el estado reproductivo o el sexo sobre dichos patrones. En este estudio, examinamos cómo los patrones de actividad del murciélago nectarívoro Leptonycteris yerbabuenae varían según su condición reproductora, su sexo y según las condiciones ambientales. Analizamos cinco años de datos de recapturas de individuos marcados mediante Transpondedores Integrados Pasivos (PIT-tags), utilizando detecciones diarias de L. yerbabuenae en tres refugios subterráneos en la Península de Baja California, México. Desarrollamos cuatro métricas a partir de las detecciones diarias en las entradas de los refugios, con la finalidad de delimitar los períodos que los individuos pasan dentro y fuera del refugio (hora de emergencia, frecuencia de regreso al refugio, horas de descanso y horas de actividad). Encontramos diferencias entre hembras preñadas, lactantes y no reproductivas en cuanto a la frecuencia de regreso al refugio, las horas dentro del refugio y las horas de actividad fuera del refugio. Las hembras lactantes pasaron más tiempo fuera del refugio, lo que sugiere que las demandas energéticas de la lactancia requieren períodos de búsqueda de alimento más prolongados. En contra de lo esperado, las hembras lactantes mostraron la menor cantidad de retornos al refugio durante la noche, lo que sugiere que las hembras lactantes no reducen los períodos de búsqueda de alimento para regresar a amamantar a las crías. Los patrones de actividad fueron diferentes entre hembras y machos, así como entre las temporadas con diferente disponibilidad de alimento. Las hembras regresaron menos durante la noche y pasaron más tiempo fuera del refugio en comparación con los machos. La hora de emergencia de los machos fue más temprana que la de las hembras, excepto durante la temporada de disponibilidad de néctar, que es cuando la mayoría de las hembras se encuentran reproductivamente activas. Las diferencias en los patrones de actividad en función del estado reproductivo, el sexo y las condiciones ambientales muestran cómo los individuos modifican su comportamiento para satisfacer sus demandas energéticas. Demostramos que los datos de recaptura de individuos utilizando los sistemas de marcaje PIT-tag en la entrada de los refugios se pueden utilizar para comparar los patrones de actividad de murciélagos gregarios.

Plateau pikas (Ochotona curzoniae) play a keystone role in the alpine meadow ecosystem on the Qinghai–Tibetan Plateau (QTP). For decades, QTP grasslands have become degraded to some degree, largely as a result of heavy livestock grazing. Concomitantly, the abundance of plateau pikas has increased dramatically as grassland degradation has altered the vegetation community structure and dominant species, shifting the plant nutrient contents toward higher protein conditions that favor them. Considerable research supports the hypothesis that the quantity and quality of food limit herbivore populations. Here, we examined the relationship between the availability of essential amino acids in the diets of plateau pikas and the degree of meadow degradation associated with livestock grazing intensity through a field survey, as well as the fitness of individuals by laboratory feeding experiments with 2 pelleted chows containing 0.26% and 0.45% methionine. Sulfur-containing methionine and cystine were the most limiting amino acids in the diets of pikas. During the pika breeding season, the concentrations of most essential acids, particularly methionine and cystine, were higher in heavily degraded meadows than in lightly and moderately degraded meadows. Individuals fed 0.45% methionine exhibited enhanced cell-mediated immunity, reduced intensity of coccidian infection, and increased concentrations of gonadotropin-releasing hormone, luteinizing hormone, estradiol, progesterone, and testosterone compared to those fed 0.26% methionine. These results showed that heavily degraded meadows provided relatively high-quality food that improved individual fitness, suggesting that the high-methionine food in the heavily degraded meadows may be a key factor in the generation and maintenance of high-density populations of plateau pikas.

高原鼠兔（Ochotona curzoniae）是青藏高原高寒草甸生态系统的关键物种。然而，近几十年来，青藏高原草地退化程度不断加剧，过度放牧是主要原因。在草地退化过程中，植被群落结构和优势物种发生变化，植物养分含量朝着高蛋白质方向转移，从而导致高原鼠兔数量急剧增加。大量研究表明，食物的数量和质量是限制食草动物数量的重要因素。因此，本研究通过野外调查研究了高原鼠兔食物中必需氨基酸的可用性与牲畜放牧强度相关的草地退化程度之间的关系。此外，我们在实验室使用 0.45%和 0.26%蛋氨酸含量的兔颗粒饲料分组饲喂高原鼠兔，以评估蛋氨酸对个体适合度的影响。结果表明，含硫氨基酸（蛋氨酸 + 胱氨酸）是高原鼠兔食物中最主要的限制性氨基酸。高原鼠兔的繁殖季节，在重度退化草地上，大部分必需氨基酸的浓度，尤其是蛋氨酸和胱氨酸的浓度均高于轻度和中度退化的草地。与饲喂 0.26%蛋氨酸的个体相比，饲喂 0.45%蛋氨酸的个体的细胞介导免疫能力增强，球虫感染强度降低，促性腺激素释放激素、黄体生成素、雌二醇、孕酮和睾酮的浓度增加。这些结果表明，重度退化草地提供了相对优质的食物，提高了个体适合度，揭示重度退化草地中的高蛋氨酸食物可能是产生和维持高原鼠兔高密度种群的关键因素。

Food caching and haying can help species to survive extreme environmental conditions and cope with seasonal fluctuations in resource availability. We documented the food caching/haying behavior of the Ladakh Pika (Ochotona ladacensis) and the Nubra Pika (O. nubrica) from the cold desert of the Changthang biotic province, Ladakh, India, and contrasted their haying strategies under differing conditions of sociality and niche occupation. We found that the more social and larger species, O. ladacensis—which lives in open microhabitats—built larger and more conspicuous haypiles compared to O. nubrica—which built smaller, concealed haypiles in less open microhabitats. Ochotona ladacensis collected a different set of plants with greater overall richness than O. nubrica. Both species collected distasteful, toxic plants that are known to discourage herbivory. Ochotona nubrica placed haypiles closer to burrows in comparison to O. ladacensis. Haypiles in O. ladacensis colonies were clumped rather than uniformly distributed, not meeting predictions of the theory of cache defensibility associated with theft by conspecifics. The present study provides insights into haypile characteristics and associated behavioral responses of high-elevation pikas to variation in the availability of resources.

The life cycles of bats are constrained by availability of resources such as food and shelter. Disruptions limiting otherwise naturally regulated access to these resources ultimately affect the fitness of bat populations and may eventually lead to local extinctions. We sampled bats before and after an Amazonian mega-dam water filling and retrieved data on their reproductive phenology, testing if and how sex ratio, seasonal abundance, and reproductive patterns respond to impacts of the newly operating hydroelectric dam. We analyzed data from 3,298 bat captures of 49 species. Females outnumbered males, previously and after the dam implementation, and we observed seasonal variations in the abundance of bats, which was lower after the implementation of the dam for most species. All species had at least 1 reproductive peak of pregnancy and/or lactation beginning at a variable time across seasons. Most species and functional ensembles were reproductively bimodal, with exceptions being the polymodal Artibeus obscurus and unimodal Phylostomus elongatus. Operations of the hydroelectric dam affected the abundance of both sexes equally, and effects were stronger in the rainy season, altering the timing of reproduction for females, delaying and shortening pregnancy and lactation. These changes expressed in female reproductive activity may be related to the shortfall of resources because of loss of irreplaceable vegetation caused by the dam filling. As we cannot predict the roles of variation of reproductive patterns observed after the filling in the long run we reinforce the importance of long-term, continuous monitoring and management to safeguard the reestablishment of reproductive patterns of females in order to repopulate and keep bat populations healthy in remaining areas along following dam construction.

O ciclo de vida dos morcegos é limitado por recursos como comida e abrigo. Interferências aos acessos, naturalmente regulados, a esses recursos podem afetar a aptidão das populações de morcegos e levar a eventuais extinções locais. Nós coletamos dados sobre a fenologia reprodutiva de morcegos Phyllostomidae antes e depois do enchimento de uma barragem hidrelétrica para testar se a proporção sexual, a abundância sazonal e os padrões reprodutivos responderiam aos impactos da operação imediata da hidrelétrica de Santo Antônio no rio Madeira, Amazônia Ocidental. Nós analisamos um total de 3.298 capturas de morcegos e dados de 49 espécies e observamos que fêmeas são mais abundantes que machos antes e após a implantação da barragem. Além disso, o represamento do rio interferiu na variação sazonal da abundância de morcegos, que foi menor após barragem para a maioria das espécies. Todas as espécies tiveram ao menos um pico reprodutivo (gravidez, lactação), variando o tempo de início ao longo das estações, sendo que a maioria das espécies e guildas foram bimodais, com exceção de Artibeus obscurus (polimodal) e Phylostomus elongatus (unimodal). A operação da hidrelétrica afetou igualmente a abundância de ambos os sexos, e os efeitos foram mais fortes na estação chuvosa, alterando o tempo de reprodução das fêmeas, retardando e encurtando a gravidez e a lactação. Embora essas mudanças nos padrões reprodutivos possam estar relacionadas à escassez de recursos devido à perda de vegetação, não podemos prever os papéis da sazonalidade e da razão sexual a longo prazo para repovoar e estruturar as populações de morcegos das áreas remanescentes pós-barragem. Reiteramos a importância do monitoramento e manejo contínuo e de longo prazo para assegurar esforços para o restabelecimento dos padrões reprodutivos das fêmeas e para manter populações saudáveis de morcegos na região.

Maintaining water balance is imperative for organismal survival. Various socioecological conditions such as sex, reproductive state, and dominance rank can impact water intake and hydration status. Eastern Chimpanzees (Pan troglodytes schweinfurthii) present an interesting biological model to investigate the socioecological correlates of hydration status, given adult sex differences in behavior. Males are more gregarious than females, which may afford them less behavioral flexibility to reduce dehydration risk. However, females invest heavily in their offspring, producing a water heavy milk for up to 5 years, and adult females experience disparities in access to water in foods dependent on dominance rank, which may cause variation in hydration status. In the present study, we investigated correlates of adult chimpanzee hydration status at Gombe National Park, Tanzania, using a measure of urine concentration—urine specific gravity (USG)—highly concentrated urine results in a higher USG, indicating dehydration. We found that both males and females had significantly higher USG in the dry season, but males had lower USG than females during the dry season. Within females, reproductive state did not significantly impact hydration status; however, females in middle lactation tended to have higher USG than nonpregnant, nonlactating females. Additionally, high-ranking females had lower USG than mid- and low-ranking females. While our study showed consistency with USG values that have been demonstrated at other Chimpanzee research sites, we found evidence that this population may be chronically dehydrated by human standards, but more research is needed across populations to determine the health and fitness effects of chronic dehydration in Chimpanzees.

The Plains Spotted Skunk (Spilogale interrupta) is a small carnivore native to central North America that has experienced significant population reductions, and there is a lack of information about the species that could inform conservation. Our study aimed to address knowledge gaps about the distribution and habitat associations of the species in South Dakota using species distribution modeling. We used species location data collected from state natural resource managers, trappers, and members of online social media groups dedicated to hunting and wildlife conservation; environmental predictors; and 6 predictive modeling algorithms (i.e., artificial neural networks, artificial classification tree analysis, generalized boosting models, maximum entropy, multivariate adaptive regression splines, and random forests) to develop climate and landcover ensemble distribution models. The most important climate and landcover predictors were mean temperature diurnal range (i.e., average monthly differences between daily high and low temperatures) and proportion of area classified as pasture. Ensemble model concordance identified approximately 31,300 km2 of potential Plains Spotted Skunk habitat primarily in eastern South Dakota and between the watersheds of the Missouri and James rivers. Our results offer insights that can guide conservation and inform effective management strategies for conserving Plains Spotted Skunk populations in the northern Great Plains. The promotion of low-intensity agricultural practices such as maintaining pastures, farm buildings, fences rows, and the management of woodland encroachment may improve habitat suitability and facilitate the recovery of plains spotted skunks in the region.

Urbanization presents a myriad of challenges to wildlife, yet some individuals or species persist and even thrive in urban environments. Specific behavioral traits that have been proposed to enable animals to cope with challenges and frequently observed in urban wildlife populations across many taxonomic groups include changes in docility, activity, boldness, sociability, and aggression. We conducted a series of standardized behavioral assays to test the hypothesis that urbanization favors these traits in fox squirrels (Sciurus niger), a species that is widespread in urban areas. Based upon previous studies, we predicted that squirrels would exhibit higher levels of boldness, activity, and aggression and lower docility in urban areas with higher human density compared to their counterparts in areas with lower human density areas. We instead found a trend of higher sociability—but not aggression—in squirrels at higher human density sites over lower human density sites, and no differences in docility, boldness, or activity. Our results indicate that the behavior of fox squirrels does not vary dramatically on a fine scale of human density, apart from a trend in heightened sociability in higher human density urban environments.

La urbanización plantea innumerables retos a la fauna salvaje, pero algunos individuos o especies persisten e incluso prosperan en entornos urbanos. Se han propuesto rasgos conductuales específicos que permiten a los animales hacer frente a tales retos, y los cam-bios en docilidad, actividad, audacia, sociabilidad y agresividad son algunos de los rasgos observados con frecuencia en poblaciones de fauna urbana de muchos grupos taxonómicos. Llevamos a cabo una serie de ensayos estandarizados de comportamiento para probar la hipótesis de que la urbanización favorece estos rasgos en ardillas zorro (Sciurus niger), una especie muy extendida en zonas urbanas. Basándonos en estudios anteriores, predijimos que las ardillas mostrarían mayores niveles de audacia, actividad y agresividad, asi como menor docilidad en zonas urbanas con alta densidad humana en comparación con sus homólogas en zonas con menor densidad humana. En cambio, encontramos una tendencia de mayor sociabilidad, pero no de agresión, en las ardillas de zonas con alta densidad humana frente a las de zonas con menor densidad humana, y ninguna diferencia en docilidad, audacia o actividad. Nuestros resultados indican que el comportamiento de las ardillas zorro no varía drásticamente en una escala fina de densidad humana, aparte de una tendencia a una mayor sociabilidad en entornos urbanos de alta densidad humana.

The fast-growing expansion of urban areas pose severe pressures on wildlife. However, some generalist native mammals thrive in urbanized landscapes, while invasive alien species (IAS) are often more abundant in cities than in rural habitats. Variation in phenotypes—such as differences in personality traits—can influence the probability to colonize anthropized areas, especially in the case of IAS where certain traits are related to invasion success. Here, we investigated the expression of activity, exploration, and social tendency in the invasive alien Eastern Gray Squirrel (Sciurus carolinensis) in replicated study sites along a rural–urban gradient in Northern Italy. Personality traits expression was estimated using an open field test (OFT) followed by a mirror image stimulation (MIS) test. We found that squirrels were more active in urban than in suburban and rural sites, and behaved more sociable in urban than in suburban sites. Conversely, exploration did not differ along the gradient. Results also reveal the presence of a behavioral syndrome: activity (OFT), social tendency, and activity–exploration (MIS). We suggest that variation in activity level and social behavior in urban habitats could favor some species to respond positively to urbanization. This study sheds light on the underexplored personality–urbanization relationship in IAS, helping to understand the complex process of invasion.

The consequences of intraguild predation on vulnerable subordinate species are an important consideration in the recovery of endangered species. In prairie ecosystems, coyotes (Canis latrans) are the primary predator of endangered black-footed ferrets (Mustela nigripes; hereafter, ferrets) and presumably compete for prairie dog (Cynomys spp.) prey. Coyote predation of ferrets is thought to occur at night when ferrets are active aboveground; however, the apparent source of competition, diurnal prairie dogs, are belowground and inaccessible to coyotes at this time, presenting a perplexing temporal mismatch between actual and expected times that coyotes and ferrets come into conflict. Our study used remote wildlife cameras, occupancy models, and overlap of circadian activity patterns to investigate how landscape features, prairie dog colony attributes, and attraction to sympatric species, i.e., American badgers (Taxidea taxus; hereafter, badgers) and lagomorphs (cottontail rabbits and jackrabbits) influence Coyote use of prairie dog colonies and potential Coyote–ferret interactions. We first evaluated Coyote use (i.e., occupancy) between prairie dog colonies and surrounding available grasslands, finding that coyotes whose home ranges include prairie dog colonies used colonies nearly twice as much as surrounding grasslands. Next, we investigated biotic and abiotic factors that may influence Coyote use and frequency of use (i.e., detection probability) on prairie dog colonies. We found high Coyote use across all areas on prairie dog colonies; however, their frequency of use increased in areas that were also used by badgers. High overlap between Coyote and badger activity patterns (81%) further supports the spatial use patterns revealed by our occupancy analysis, and badgers and coyotes are known to form hunting associations. Interspecific competition and overlapping patterns of resource use between badgers and ferrets have been documented in previous studies; our study supports these findings and suggests that Coyote attraction to badger activity may influence Coyote–ferret interactions.

Las consecuencias de la depredación intragremial sobre especies subordinadas vulnerables son una consideración importante en la recuperación de especies en peligro de extinción. En ecosistemas de pradera, los coyotes (Canis latrans) son el depredador primario de los hurones de pies negros (Mustela nigripes; en adelante, hurones) en peligro de extinción y presumiblemente compiten por las presas de los perritos de las praderas (Cynomys spp.). Se cree que la depredación de hurones por parte de los coyotes ocurre durante la noche, cuando los hurones están activos en la superficie; sin embargo, la fuente aparente de competencia, los perritos de las praderas diurnos, están bajo tierra y son inaccesibles para los coyotes en este momento, lo que presenta un desconcertante desajuste temporal entre los momentos reales y esperados en que los coyotes y los hurones entran en conflicto. Nuestro estudio utilizó cámaras trampa, modelos de ocupación y superposición de patrones de actividad circadiana para investigar cómo las características del paisaje, los atributos de las colonias de perritos de las praderas y la atracción por especies simpátricas (es decir, tejones americanos, Taxidae taxus y lagomorfos) influyen en el uso de las colonias de los perritos de las praderas por parte de los coyotes e interacciones potenciales entre coyote-hurón. Primero evaluamos el uso de coyotes (es decir, ocupación) entre las colonias de perritos de las praderas y los pastizales circundantes disponibles, y encontramos que los coyotes cuyo territorio colinda con colonias de perritos de la pradera usaban las colonias casi el doble (Ψ^{^} = 0,77, IC del 95% [0,48, 0,93]) que los pastizales circundantes (Ψ^{^} = 0,37; IC del 95% [0,21; 0,57]). Después investigamos los factores bióticos y abióticos que pueden influir en el uso y la frecuencia de uso de los coyotes (es decir, la probabilidad de detección) en las colonias de perritos de las praderas. Encontramos un alto uso por parte de los coyotes en todas las áreas de las colonias de perritos de las praderas; sin embargo, su frecuencia de uso aumentó en áreas que también eran utilizadas por tejones (β = 3,95, IC del 95% [2,35, 5,58]). La alta superposición entre los patrones de actividad de coyotes y tejones (81%) respalda aún más los patrones de uso espacial revelados por nuestro análisis de ocupación, y se sabe que los tejones y los coyotes forman asociaciones de caza. En estudios previos se han documentado la competencia interespecífica y los patrones superpuestos de uso de recursos entre tejones y hurones; nuestro estudio respalda estos hallazgos y sugiere que la atracción del coyote por la actividad del tejón puede influir en las interacciones coyote-hurón.

Female and male cooperative breeders can use different strategies to maximize reproduction and fitness over their lifetimes. Answering questions about fitness in cooperative breeders requires long-term studies as well as complete data on group composition and size which can be exceedingly difficult to obtain. Using a long-term genetic data set of complete group pedigrees, I asked how lifetime reproductive characteristics of female and male gray wolves (Canis lupus) differed. I predicted that genetic relatedness to helpers would be higher for females than males due to philopatric behavior of female wolves, group size would be similar between the sexes, females would inherit breeding positions from within groups more often than males due to differences in dispersal strategies between the sexes, males would have more lifetime mates and produce more young than females because of polygamy, and females would breed for more years than males due to the likelihood that females would still breed (with a new partner) after a mate died or was expelled from the group. I documented complete lifetime breeding histories for 11 male and 18 female wolves in Idaho, United States, 2008 to 2018. Genetic relatedness to helpers, group size, number of mates, pups, and years breeding did not differ between the sexes. Females, however, inherited breeding positions within groups far more often than males. Individuals who secured breeding positions generally reproduced for 2 seasons and commonly had more than 1 partner during their lifetimes if they were able to maintain their breeding position longer. Direct fitness varied greatly within female and male breeding wolves.

Las hembras y los machos que presentan crianza cooperativa pueden utilizar diferentes estrategias para maximizar la reproducción y la aptitud biológica a lo largo de sus vidas. Responder preguntas sobre la aptitud biológica de la crianza cooperativa requiere estudios a largo plazo, así como datos completos sobre la composición y el tamaño del grupo, que pueden ser extremadamente difíciles de obtener. Utilizando un conjunto de datos genéticos de largo plazo de genealogías grupales completas, investigué en qué se diferenciaban las características reproductivas a lo largo de la vida de las hembras y los machos de los lobos grises (Canis lupus). Predije que la relación genética con los ayudantes sería mayor para las hembras que para los machos; el tamaño del grupo sería similar entre los sexos; las hembras heredarían posiciones reproductivas dentro de los grupos con más frecuencia que los machos; los machos tendrían más parejas a lo largo desu vida y producirían más crías que las hembras debido a la poligamia; y que las hembras se reproducirían durante más años que los machos. Documenté la historia reproductiva a lo largo de la vida de 11 lobos machos y 18 hembras en Idaho, EE. UU., 2008-2018. La relación genética con los ayudantes, el tamaño del grupo, el número de parejas, las crías y los años de reproducción no difirieron entre los sexos. Sin embargo, las hembras heredaron posiciones reproductivas dentro de los grupos con mucha más frecuencia que los machos. Los individuos que aseguraron posiciones reproductivas generalmente se reprodujeron durante dos temporadas y comúnmente tuvieron más de una pareja durante su vida si pudieron mantener su posición reproductiva por más tiempo. La aptitud biológica directa varió mucho entre las hembras y los machos de los lobos reproductores.

Cumulative costs of reproduction are predicted by life-history theories of aging, but empirical support for cumulative costs of reproduction in ungulates is limited. Examinations of the relationship between previous reproductive effort and future reproductive output are often limited to successive years. We analyzed pregnancy status, lactation duration, and age class of Elk (Cervus canadensis) in Utah, United States, from 2019 to 2022 to better understand the relationship between previous reproductive effort and future reproductive output, particularly in nonsuccessive years. Pregnancy status 1 year prior, pregnancy status 2 years prior, and age had no effect on the likelihood of pregnancy in Elk. However, lactation duration 1 year prior and lactation duration 2 years prior had a negative effect on the likelihood of pregnancy. The best-fitting model to explain the relationship between pregnancy status and previous lactation was the positive interaction between lactation duration 1 year prior and lactation duration 2 years prior. The results of our study suggest long-lasting (i.e., multiple-year), cumulative costs of reproduction can influence reproductive output in female Elk, but differences in individual quality may have an even greater influence. High-quality individuals may be able to override the costs of reproduction and minimize reproductive trade-offs.

Spatial patterns in topography and forage distribution significantly influence the movements and choices of large herbivores. However, understanding the foraging strategies of free-grazing herbivores at different temporal and spatial scales remains limited, as different behavioral decisions can apply at different hierarchical levels. This study investigates the fine-scale foraging strategies of the Plains Zebra (Equus quagga) in a South African savanna, with a specific focus on their selection of green vegetation at the plant and feeding patch levels. We used the Normalized Difference Vegetation Index as a proxy for vegetation productivity and quality. Our findings reveal that zebras adapted their foraging strategies according to scale and season. During the late-dry season and early-wet season, selection for greenness was at both the grass tuft and feeding site levels. In contrast, during the mid-dry season, selection was predominantly at the tuft level, focusing solely on greenness. These insights emphasize the importance of conducting multilevel studies when investigating factors influencing foraging decisions. Findings at 1 hierarchical level may not necessarily apply across other levels of investigation, highlighting the need for a nuanced and comprehensive approach to understanding the complex foraging behaviors of animals.

Habitat use influences the survival and fitness of animals. Habitat quality and food availability in spring and summer are crucial determinants of ungulate population dynamics, peaking in spring and drastically decreasing in summer in Mediterranean region. Here, over a 2-year period we examine foraging habitat use in both spring and summer of 3 threatened gazelle species living in sympatry in a private reserve in Morocco: Cuvier's Gazelle (Gazella cuvieri), Dama Gazelle (Nanger dama), and Dorcas Gazelle (G. dorcas). We observed differences among species—Cuvier's Gazelle foraged in woodland, Dama Gazelle in grassland, and Dorcas Gazelle in scrubland—with differences being mediated by seasonal effects as all species broadened their foraging habitat use in summer. We observed differences between years in foraging patterns of Dama Gazelle and Dorcas Gazelle, reflecting greater herb and scrub cover in 2018, potentially related to greater rainfall. Given the seasonal and annual differences observed, reductions in rainfall predicted with the progression of changing climatic conditions in the Mediterranean basin would reduce the availability of food resources and heighten the vulnerability of these species. The study illustrates interspecific coexistence through food resource partitioning of the 3 species, contributing to support conservation management actions of their populations in setting up structured reintroduction programs within their range.

Over the last century, Texas has been inundated with exotic ungulates, with as many as 67 species represented by captive and free-ranging populations. One of the most successful species to have established free-ranging populations is the Aoudad (Ammotragus lervia). Herein, we expand on previous genetic studies in Aoudad by including new genomic profiles based on double-digest restriction site-associated DNA sequencing methods with the intent of better understanding the effects of >70 years of human-mediated translocations, population expansion, and gene flow among populations. Using a range of 4,338 to 5,529 single-nucleotide polymorphisms obtained from 73 individuals that potentially represented A. l. blainei, A. l. lervia, and A. l. sahariensis, we measured genetic patterns of diversity and connectivity between source populations from California and New Mexico and resultant aoudad populations in Texas. Principal component analyses identified phylogeographically structured populations across Texas. Further, we identified a signature of isolation by distance among Texas populations. To assess geographic regions that facilitated or blocked gene flow between populations, we used estimation of effective migration surfaces, which indicated 3 barriers to movement between populations as well as connectivity among populations in close proximity. Comparison of mtDNA haplogroups and nuclear genotypes among the 3 examined subspecies were discordant, indicating that the current subspecific taxonomic classification needs refinement. Given the vulnerable status of Aoudad in their native range of northern Africa and the exponential population growth and potential competition with native ungulates in Texas, we propose that efforts to manage non-native Aoudad should strive to maintain and preserve unique genetic units while minimizing competition and other detriments to native species in Texas. Conservation efforts are especially important given the vulnerable status of Aoudad within their native range of northern Africa.

Specimen-based taxonomic research is essential for understanding diversity and setting management frameworks for threatened mammal faunas, and ancient DNA techniques are increasingly used to extract information from taxonomically relevant historical specimens. The largest survivors of the depleted Caribbean mammal fauna are hutias in the genus Capromys, which is usually interpreted as containing a single species, C. pilorides. Previous studies have demonstrated genetic differentiation of Capromys populations across Cuba, but infrageneric species diversity and nomenclature remain unclear. We conducted ancient DNA analysis of historical Capromys samples using cytochrome b and complete mitogenome data sets, and including the 19th-century holotypes of 2 species now considered synonyms, C. fournieri and C. geayi. Our analyses identify distinct western and central/eastern Capromys clades that diverged 1.75 Mya based upon mitogenome data. These clades are separated by the Havana–Matanzas Channel, which represented a barrier to dispersal throughout the Neogene–Quaternary. Divergence date comparisons with other hutia species provide support for interpreting divergence between Capromys populations as species-level differentiation. Although we were unable to yield amplifiable DNA from the C. fournieri holotype, our analyses confidently assign the C. geayi holotype to the western Capromys clade. We therefore recognize 2 extant Capromys species: C. geayi (western Cuba) and C. pilorides (central/eastern Cuba and Cayman Islands).

La investigación taxonómica basada en especímenes es esencial para comprender la diversidad y establecer marcos de gestión para las especies de mamíferos más amenazadas, y las técnicas de ADN antiguo se utilizan cada vez más para extraer información de especímenes históricos relevantes desde el punto de vista taxonómico. Los mas grandes sobrevivientes de la fauna de mamíferos del Caribe agotada son las jutías del género Capromys, que generalmente se interpreta que contiene una sola especie, C. pilorides. Estudios previos han demostrado la diferenciación genética de las poblaciones de Capromys en toda Cuba, pero la diversidad de especies infragenéricas y la nomenclatura siguen siendo poco claras. Realizamos un análisis de ADN antiguo de muestras históricas de Capromys utilizando conjuntos de datos de citocromo b y mitogenoma completo, incluyendo los holotipos del siglo XIX de dos especies reconocidas como sinónimos, C. fournieri y C. geayi. Nuestros análisis identifican clados distintos de Capromys occidentales y centrales/orientales que divergieron hace 1.75 millones de años según los datos del mitogenoma. Estos clados están separados por el Canal de La Habana-Matanzas, que representa una barrera para la dispersión a lo largo del Neógeno Cuaternario. Las comparaciones de fechas de divergencia con otras especies de jutías respaldan la interpretación de la divergencia entre las poblaciones de Capromys como una diferenciación a nivel de especie. Aunque no pudimos obtener ADN amplificable del holotipo de C. fournieri, a través de nuestros análisis podemos asignar con certeza el holotipo de C. geayi al clado occidental de Capromys. Por lo tanto, reconocemos dos especies existentes de Capromys: C. geayi (occidental de Cuba) y C. pilorides (centro/oriente de Cuba y las Islas Caimán).

The House Mouse, Mus musculus, is a model organism that has greatly contributed to evolutionary research. Despite its significance, there remain gaps in our understanding of its phylogeography and population genetic structure in Asian regions. This comprehensive study aims to elucidate the evolutionary history, genetic diversity, and distribution patterns of M. musculus. A diverse data set of 281 M. musculus samples was collected from across Asia, covering 101 localities in 19 countries. Phylogenetic analysis using Cytochrome b and D-Loop region unveiled well-supported lineages. These lineages correspond to: M. m. musculus, M. m. domesticus, M. m. castaneus, and M. m. bactrianus. Also, validity of M. m. bactrianus was questioned. The analysis suggests a monophyletic origin of these subspecies approximately 0.59 million years ago (Mya), followed by 2 main lineages—one consisting of M. m. domesticus (∼0.59 Mya) and the other comprising M. m. castaneus, M. m. bactrianus, and M. m. musculus (∼0.56 Mya). Genetic diversity varied among subspecies, with M. m. domesticus exhibiting the highest diversity due to its extensive global distribution and M. m. bactrianus exhibiting the lowest diversity due to restriction in southwest Asia. Pairwise genetic distances and F_st values confirmed significant genetic differentiation among the subspecies, underlining their historical isolation. Additionally, a Mantel test indicated that geographical distance played a pivotal role in shaping genetic differentiation. Demographic analysis revealed evidence of population expansions in M. m. domesticus, M. m. musculus, and M. m. castaneus, while M. m. bactrianus showed characteristics of neutral selection and genetic drift. Species distribution modeling, assessing both Current Conditions and the Last Glacial Maximum, indicated habitat shifts and losses during glacial periods, particularly in the eastern and northern regions of Asia. However, each subspecies displayed unique responses to climatic changes, reflecting their distinct ecological adaptations. Historical biogeography analysis pointed to complex origins and a network of dispersal and vicariance events that led to the contemporary distribution of subspecies. Deserts and xeric shrublands emerged as critical areas for diversification and speciation. This study contributes to our understanding of the phylogeography and population genetics of M. musculus in Asia, highlighting the significance of geographical factors and climatic fluctuations in shaping its evolutionary history and genetic diversity.

The correlates of mammal species richness and community associations along elevation gradients have resulted in conflicting results within tropical systems. We surveyed the terrestrial mammal and gallinaceous bird community (>200 g body size) along transects at 4 mountain sites in Malaysian Borneo using camera traps to assess structuring of the mammal community along the elevation gradient. Between 2015 and 2021, we surveyed Bukit Lanjak (elevation 1,300 m) in Sarawak (Lanjak Entimau Wildlife Sanctuary; LEWS) and Mts. Kinabalu, Tambuyukon, and Magdalena (up to 2,400 m) in Sabah, with a total sample effort of 20,600 camera nights. We detected 48 species of mammals and 9 species of large terrestrial birds. There was mostly a common species pool across the sites, with only 9 species detected solely in LEWS and 5 species only in Sabah. Over our limited elevation range, no species were detected across the entire elevation range and no common species were confined to the highest elevation sites in Sabah or LEWS (>1,000 m). A species richness curve for each location indicated a slight peak at ∼1,000 m for LEWS, but the mid-elevation peak was not evident at Sabah. The individual response curves of relative abundance to the elevation gradient for 15 species with sufficient detections were similar across sites (1 exception—Malaysian Porcupine) with 6 species showing no correlation with elevation, while 4 species increased and 4 species decreased in detections with elevation. A multivariate analysis of species detections found herbivores at lower elevations and mesocarnivores at higher elevations, while species of the same foraging guilds differed in body size at the same elevation. As opposed to studies focused on smaller vertebrate species (i.e., rodents, songbirds), larger mammal and terrestrial bird communities in these mountains did not form unique communities along the elevation gradient but did structure according to the functional traits of foraging guilds and body size.

Declines in populations of small mammals associated with high elevations, e.g., marmots (Marmota spp.) and pikas (Ochotona spp.), have been attributed to both direct and indirect effects of environmental changes caused by humans. For example, populations of Olympic marmots (M. olympus) and Vancouver Island marmots (M. vancouverensis) have declined in response to increased predator access to high-elevation marmot habitats. In the North Cascades National Park Service Complex (NOCA), observed mean abundance of hoary marmots (M. caligata) declined by 74% from 2007 to 2016. Although these declines have been linked to harsh winter conditions, the role of predation and its association with decreasing snowpack has yet to be explored in this system. We noninvasively examined these predator–prey dynamics by coupling behavioral surveys of hoary marmots with indices of predation risk. We conducted 145 vigilance samples and 39 flight initiation distance trials to measure Hoary Marmot antipredator behavior. We derived a risk index for each predator by weighting its probability of use estimates (the probability of a predator–prey encounter) with its observed proportion of Hoary Marmot predation (probability of prey death given an encounter). We used genetic metabarcoding of vertebrate DNA from 413 predator scat samples to quantify predation on hoary marmots. We surveyed 9,930 trap-nights using 130 remote cameras to model predator probability of use near Hoary Marmot colonies. From camera traps and scat DNA, we detected 10 predator species in the study area, and we detected hoary marmots in the scats of 5 of these species. The proportion of observed Hoary Marmot predation was highest for coyotes (Canis latrans) at 50%. To our knowledge, we also report the first record of hoary marmots being consumed by Pacific martens (Martes caurina), which were also significant predators (proportion of observed predation = 32%). We expected predators with low-elevation habits to use sites with lesser snow persistence; this prediction was supported for coyotes but not for other typically low-elevation predators. We found estimated risk experienced by hoary marmots was highest from Pacific martens and lowest from Canada Lynx (Lynx canadensis). Contrary to our predictions and despite hoary marmots allocating >50% of their time to vigilance, neither estimates of predator risk nor human presence explained variation in marmot antipredator behavior. Based on the results from both our dietary and probability of use analyses, we expect coyotes to have an increasing effect on NOCA's Hoary Marmot population as the climate warms and Coyote range continues to expand. Thus, our work highlights the need to better understand the effect of climate-driven shifts in predator–prey ecology in high-elevation systems.

The American Pika (Ochotona princeps) has been considered a species at risk due to warming temperatures associated with climate change. Many life-history attributes of pikas contribute to the sensitivity of pikas to warming temperatures. Repeated censuses of a marginal (warm, low-elevation) population of pikas at Bodie State Historic Park, California, conducted from 1972 to 2022, are presented to track the population trajectory of pikas for a time period predating recent awareness of global warming to the present day, thus giving a comprehensive portrayal of how American pikas may be responding to climate change. The northern constellation of anthropogenic habitat patches (mine ore dumps) showed no decline in percent of patches occupied or in total number of pika territories over time, suggesting that pikas in that area have not been at risk of extirpation resulting from climate change. In contrast, the pika population in the southern constellation of patches showed significant declines in percent of patches occupied and number of pika territories occupied. That area was unoccupied for about a decade beginning in 2006, but was recently recolonized from the northern constellation of patches. The most likely cause of the initial decline and transient extirpation in the south appears to result from fragmentation and stochastic population dynamics, independent of climatic factors that we investigated. Assessments of climatic impacts on American pikas should take into account the dynamics documented in the Bodie pika population and its resilience over time.

The timing and nature of evolutionary shifts in the relative brain size of Primates have been extensively studied. Less is known, however, about the scaling of the brain-to-body size in their closest living relatives, i.e., among other members of Euarchontoglires (Dermoptera, Scandentia, Lagomorpha, Rodentia). Ordinary least squares (OLS), reduced major axis (RMA), and phylogenetic generalized least squares (PGLS) regressions were fitted to the largest euarchontogliran data set of brain and body mass, comprising 715 species. Contrary to previous inferences, lagomorph brain sizes (PGLS slope = 0.465; OLS slope = 0.593) scale relative to body mass similarly to rodents (PGLS = 0.526; OLS = 0.638), and differently than primates (PGLS = 0.607; OLS = 0.794). There is a shift in the pattern of the scaling of the brain in Primates, with Strepsirrhini occupying an intermediate stage similar to Scandentia but different from Rodentia and Lagomorpha, while Haplorhini differ from all other groups in the OLS and RMA analyses. The unique brain–body scaling relationship of Primates among Euarchontoglires illustrates the need for clade-specific metrics for relative brain size (i.e., encephalization quotients; EQs) for more restricted taxonomic entities than Mammalia. We created clade-specific regular and phylogenetically adjusted EQ equations at superordinal, ordinal, and subordinal levels. When using fossils as test cases, our results show that generalized mammalian equations underestimate the encephalization of the stem lagomorph Megalagus turgidus in the context of lagomorphs, overestimate the encephalization of the stem primate Microsyops annectens and the early euprimate Necrolemur antiquus, but provide similar EQ values as our new strepsirrhine-specific EQ when applied to the early euprimate Adapis parisiensis.

Chinchilla rats (family Abrocomidae) are hystricomorph rodents primarily inhabiting the central Andes in South America with 8 species in the genus Abrocoma and 2 in Cuscomys. The systematics of this family—relying only on morphological differences—has faced several controversies, particularly in arid-adapted species of Abrocoma (the A. cinerea species complex, or ACC). By using partial DNA sequences of 1 mitochondrial (Cytochrome b) and 2 nuclear genes (GHR and RAG1), we: (i) inferred phylogenetic relationships between 5 species of Abrocoma and 1 of Cuscomys; (ii) performed molecular species-delimitation analyses in 4 species of the ACC (A. cinerea, A. famatina, A. schistacea, and A. uspallata); and (iii) estimated divergence times using stratigraphic ages of extinct taxa. Our phylogenetic analyses recovered 3 main clades: A. bennettii (basal); C. ashaninka; and the ACC. Striking differences in habitat use, morphology, and genetics suggest that each of these main clades might represent a distinct genus. In species-delimitation analyses in the ACC, only 2 species were recognized, and we thus suggest the synonymy of A. famatina with A. cinerea and of A. uspallata with A. schistacea. The origin of extant abrocomids was estimated at the late Miocene (∼5.6 million years ago, Ma) with the subsequent origin of arboreal species during the early Pliocene (∼4.3 Ma) and the ACC during the late Pliocene (∼3.3 Ma). We hypothesize that topographic uplift of the central Andes and associated climatic and ecological changes were the main drivers of diversification in this family.

Las ratas chinchilla (familia Abrocomidae) son roedores histricomorfos que habitan principalmente los Andes Centrales de América del Sur con ocho y dos especies en los géneros Abrocoma y Cuscomys, respectivamente. La sistemática de esta familia se ha fundamentado solamente a partir de diferencias morfológicas habiendo variadas controversias, particularmente en especies de Abrocoma de ambientes áridos, el complejo de especies A.cinerea (ACC). Mediante el uso de secuencias parciales de ADN de un gen mitocondrial (citocromo b) y dos genes nucleares (GHR y RAG1): (i) inferimos las relaciones filogenéticas entre cinco especies de Abrocoma y una especie de Cuscomys; (ii) realizamos análisis de delimitación molecular de especies en cuatro especies del ACC (A. cinerea, A. famatina, A. schistacea, y A. uspallata); y (iii) estimamos los tiempos de divergencia usando las edades estratigráficas de taxones extintos. Nuestros análisis filogenéticos indican la presencia de tres clados principales, A. bennettii (basal), C. ashaninka y el ACC. Marcadas diferencias en el uso de hábitat, morfología y genética sugieren que cada uno de estos clados principales podría representar un género distinto. En los análisis de delimitación de especies en el ACC se identificaron sólo dos especies, por lo que sugerimos la sinonimia de A. famatina con A. cinerea y de A. uspallata con A. schistacea. Estimamos el origen de los abrocómidos vivientes en el Mioceno tardío (∼5.6 millones de años atrás, Ma) seguido por el origen de especies arbóreas durante el Plioceno temprano (∼4.3 Ma), y del ACC durante el Plioceno tardío (∼3.3 Ma). Proponemos que el levantamiento de los Andes centrales y sus resultantes cambios climáticos y ecológicos fueron los principales agentes de diversificación en esta familia.

Peromyscus sonoriensis is a widespread species ranging from southern Texas to the Yukon, from the Mississippi to the Pacific. Because of this extensive range, there are substantial differences in morphology due to variation in temperature, precipitation, and habitat. We used 2 data sets (n = 4,840 and n = 20,175) to study morphological differences of their crania and appendages. Consistent with Allen's rule (shorter appendages with colder temperature), both data sets show a strong, positive, correlation between tail length and the average January temperature. However, there was an equally strong, but negative, correlation between tail length and average July temperature. We observed similar results for feet and crania. Ear length had a significant negative correlation with July average temperature but no correlation with January average temperature. When we controlled for temperature, cranial and appendage length increased with latitude, which was opposite of what we expected. Furthermore, longitude had a strong impact as mice trapped further west had longer appendages. When divided into habitats, forest deer mice are more likely than prairie or desert deer mice to demonstrate morphological responses to differences in climate, location, and year trapped. Our results show that P. sonoriensis exhibit notable morphological variation linked to location, habitat, and climate.

Peromyscus sonoriensis es un clado presente desde el sur de Texas hasta el Yukón, desde el Mississippi hasta el Pacífico. Debido a esta amplia distribución geográfica, se pueden observar diferencias sustanciales en su morfología relacionadas a variaciones de temperatura, precipitación y hábitat. En este estudio se utilizaron dos conjuntos de datos para estudiar las diferencias morfológicas en el cráneo y los apéndices. Ambos conjuntos de datos mostraron una fuerte correlación positiva entre la longitud de la cola y la temperatura promedio en enero, de acuerdo con la regla de Allen (apéndice más corto en temperaturas más bajas). Sin embargo, se encontró correlación igualmente fuerte, pero negativa, entre la longitud de la cola y la temperatura promedio en julio. Se observaron resultados similares en las patas y cráneo. La longitud de las orejas tuvo una correlación negativa significativa con la temperatura promedio en julio, pero no con la temperatura promedio en enero. Al contrario de lo esperado, cuando se controló el efecto de la temperatura, el largo de los apéndices aumentó con la latitud. Sorprendentemente, la longitud tuvo un fuerte impacto, de manera que los roedores capturados más hacia el oeste tenían apéndices más largos. Cuando el área se dividió por ecorregiones, los ratones ciervos de bosque mostraro respuestas morfológicas a las diferencias en clima, ubicación y año de captura que los de pradera y desirto. Los resultados muestran que P. sonoriensis muestra notable variación en cráneo y apéndices asociada al clima y a la geografía.

Illegal killing (poaching) of wildlife is a problem that warrants legitimate and objective investigation. Treves et al. (2017) use data from reported wolf mortalities in Wisconsin to estimate unreported and unobserved mortality and poaching rates of unmonitored wolves. This publication is frequently cited and often used to advocate for various policy recommendations despite nontrivial problems in analysis resulting in incorrect inference. We provide a constructive examination of this work and we identify significant methodological and analytical flaws that lead to consequential but faulty conclusions about levels of annual mortality that wolf populations can sustain. We also contrast the conclusions of Treves et al. (2017) with established literature on wolf demographics and observed changes in the Wisconsin wolf population and conclude that the observed population growth would not have been possible with mortality rates estimated by their publication.

Human-caused mortality has been the major cause of death among wolves worldwide. In 2017, we summarized a 33-year data set of >933 Gray Wolf deaths from Wisconsin, United States, and estimated that poaching was the major source of mortality. Roberts et al. (2024; hereafter, just Roberts et al. unless using a direct quote from that paper) challenge our reinterpretation of data on causes of death and disappearances and urge us to use standard known-fates survival models rather than the combined time-to-event and total accounting methods that we used. They do not cite subsequent time-to-event and competing risk and incidence models that we published, raising an issue of selective citation of only their own work. Regarding reinterpretations, Roberts et al. neither present evidence for their claims nor revisit records of cause of death to argue their claims. Regarding traditional known-fate survival models, we review the violation of a critical assumption of such models. Namely, causes of death were not independent of censoring among Wisconsin collared wolves. Rates of disappearance approximating 42% of all collared animals are incompatible with the assumption that unknown-fate collared wolves died of the same causes as known-fate animals. We demonstrate that Roberts et al. made an erroneous claim that wolves frequently outlive the operational lives of their VHF collars. We present evidence of undisclosed competing interests among Roberts et al.'s coauthors. In scientific debates, the most transparent assumptions, methods, and data prevail because outside reviewers can judge for themselves. We stand by the conclusions of our combined analyses from 2017 to 2023.