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A central goal of ecology is to understand how environmental variation affects populations. Long-term studies of marked individuals can quantify the effects of environmental variation on key life-history traits. We monitored the survival and growth of 336 individually marked juvenile eastern grey kangaroos (Macropus giganteus), a large herbivore living in a seasonal but unpredictable environment. During our 12-year study, the population experienced substantial variation in rainfall, forage biomass, and density. We used structural equation modeling to determine how variation in temperature and rainfall affected juvenile survival and growth through its effect on forage biomass and population density. Independently of population density, forage biomass had strong positive effects on survival from 10 to 21 months. At low population density, forage biomass also had a positive effect on skeletal growth to 26 months. Increasing maternal body condition improved rearing success for daughters but not for sons. High population density reduced skeletal growth to 26 months for both sexes. Rainfall had an increasingly positive effect on forage biomass at high temperatures, indicating a seasonal effect on food availability. Our study reveals interacting effects of environmental variation on juvenile survival and growth for a large mammal with a conservative reproductive strategy that experiences substantial stochasticity in food availability.
White-nose syndrome (WNS) is caused by the fungus Pseudogymnoascus destructans and has led to the deaths of millions of North American bats since it was first documented in New York in 2006. Since the first cases were recorded, WNS has spread rapidly across North America and is now confirmed or suspected in 40 US states and seven Canadian provinces. Often, the presence of P. destructans is detected in a cave or hibernaculum before signs of WNS manifest in the resident bat population, making presence of the fungus a more reliable assessment of potential epidemic spread than expansion of manifested WNS. An analysis of 43 cave internal climates across the state of Texas revealed a pattern of thermal suitability for P. destructans that correlated significantly with landscape (elevation, lithology) and external climate (mean surface temperature and precipitation). We generated a predictive model to assess the potential spread of P. destructans through Texas karst systems based on external features that correlate with suitable internal climates for fungal growth. Applications of this model to external climatic variables from 2019 showed seasonally varying patterns of suitability for fungal growth in select regions of Texas karst systems. Results from these surveys and models showed that internal climates of Texas caves are likely able to sustain the growth of P. destructans and could cause disease and resulting declines in Texas bats, and act as stepping-stones for the fungus, allowing it to travel southward into Mexican and Central American cave systems. The resulting work will inform researchers and natural resource managers of areas of significant concern to monitor for the spread of WNS.
El síndrome de la nariz blanca (SNB) es causado por el hongo Pseudogymnoascus destructans y, desde que se documentó por primera vez en Nueva York en el 2006, ha provocado la muerte de millones de murciélagos norteamericanos. A partir de sus primeros descubrimientos, el SNB se ha difundido rápidamente a lo largo de Norteamérica, siendo su presencia actualmente confirmada o sospechada en 40 estados de EE. UU. y siete provincias canadienses. A menudo, la presencia de P. destructans se detecta en una cueva o sitio de hibernación antes de que los síntomas del SNB se manifiesten en la población residente de murciélagos, lo que hace de la presencia del hongo un método de evaluación más confiable de la difusión potencial de la epidemia en comparación con la expansión de casos con SNB manifestado. Un análisis de las condiciones climáticas internas de 43 cuevas en el estado de Texas reveló un patrón de idoneidad térmica para P. destructans significativamente correlacionado con el paisaje (elevación, litología) y las variables climáticas externas (temperatura media superficial y precipitación). En este estudio generamos un modelo predictivo para evaluar la difusión potencial de P. destructans a través de los sistemas kársticos de Texas basado en características externas correlacionadas con condiciones climáticas internas adecuadas para el crecimiento del hongo. Las aplicaciones de este modelo a variables climáticas externas del 2019 mostraron patrones de idoneidad para el crecimiento del hongo estacionalmente variables en regiones seleccionadas de los sistemas kársticos de Texas. Los resultados de este estudio y modelos indican que las condiciones climáticas internas de las cuevas en Texas pueden probablemente sostener el crecimiento de P. destructans y causar la enfermedad, con las consecuentes disminuciones de las poblaciones de murciélagos texanos, así como también actuar como stepping-stones para el hongo, permitiéndole desplazarse hacia el sur en los sistemas de cuevas mexicanos y de América Central. El trabajo resultante informará a los investigadores y administradores de recursos naturales sobre áreas de prioridad elevada para el monitoreo de la difusión del SNB.
Despite increasing awareness of the ecological roles and ecosystem services that bats provide, spatiotemporal patterns in bat abundance and community assembly remain poorly understood outside of select sites in the tropics. We conducted systematic full-spectrum acoustic surveys of bats over the course of a year at eight permanent sites spanning nearly 50 km along Putah Creek, a stream in California's Central Valley that has been subject to restoration efforts and changes to its in-stream flow regime over the past two decades. We surveyed all sites for 1 week each month. In 158 sampling nights over 11 months, we recorded 157,762 identifiable calls, thereby documenting a rich bat assemblage comprising 15 species from eight genera and two families. Seven species appeared to occur here year-round, whereas six others evidently migrated seasonally, and two were incidental visitors. Species richness and activity diversity were effectively invariant across this 50-km gradient, but assemblage composition varied both spatially and temporally. Spatial patterns suggest species-specific distributions that presumably reflect individualistic habitat preferences and responses to extrinsic factors. Species also varied temporally, with bat activity generally declining in winter, with an unexpected dip in richness and activity in late spring. For the three most commonly detected species, generalized linear models further highlighted the species-specific and individualistic nature of spatiotemporal activity patterns. When integrated with available data from other temperate sites, our results suggest that local species richness is high in temperate riparian systems. Additionally, our observations suggest that species responses to environmental variation are individualistic (e.g., “Gleasonian”) in nature and that local composition varies greatly over spatiotemporal gradients, but that emergent assemblage characteristics do not. The generality of these observations, and the underlying mechanism(s) leading to invariance in emergent characters, warrant further investigation. Similarly, the extent to which greater bat species richness provides complementary ecosystem services (hence, ecological insurance) is of both ecological and economic interest.
A pesar de la creciente conciencia de los roles ecológicos y los servicios ecosistémicos que proporcionan los murciélagos, los patrones espacio-temporales en la abundancia y el ensamble de la comunidad de murciélagos siguen siendo poco entendidos fuera de sitios selectos en los trópicos. Realizamos estudios acústicos sistemáticos del espectro completo de murciélagos en el transcurso de un año en ocho sitios permanentes que abarcan aproximadamente 50 km a lo largo de Putah Creek, un arroyo en el Valle Central de California que ha sido objeto de esfuerzos de restauración y cambios en su régimen de flujo en la corriente en las últimas dos décadas. Se realizó trabajo de campo en todos los sitios durante una semana cada mes. En 158 noches de muestreo durante 11 meses registramos 157,762 llamados identificables, documentando así un rico ensamble de murciélagos que comprende 15 especies de ocho géneros y dos familias. Siete especies parecían ser residentes todo el año, mientras que otras seis evidentemente migraron estacionalmente y dos fueron visitantes incidentales. La riqueza de especies y la diversidad de actividades fueron efectivamente invariantes a través de este gradiente de 50 km, pero la composición del ensamblaje varió tanto espacial como temporalmente. Los patrones espaciales sugieren distribuciones específicas de la especie que presumiblemente reflejan las preferencias individualistas del hábitat y las respuestas a factores extrínsecos. Las especies también variaron temporalmente, con la actividad de los murciélagos generalmente disminuyendo en invierno, con una caída inesperada en la riqueza y la actividad a fines de la primavera. Para las tres especies detectadas más frecuentemente, los modelos lineales generalizados destacaron aún más la naturaleza especie-específica e individualista de los patrones de actividad espacio-temporal. Cuando se integran con los datos disponibles de otros sitios templados, nuestros resultados sugieren que la riqueza de especies locales es alta en los sistemas ribereños templados. Adicionalmente, nuestras observaciones sugieren que las respuestas de las especies a la variación ambiental son individualistas (es decir, “Gleasonianas”) en la naturaleza y que la composición local varía mucho sobre los gradientes espacio-temporales, mientras que las características emergentes de ensamblajes no lo hacen. La generalidad de estas observaciones y los mecanismos subyacentes que conducen a la invariancia en los caracteres emergentes, justifican una mayor investigación. Asimismo, la medida en que una mayor riqueza de especies de murciélagos proporciona servicios ecosistémicos complementarios (por lo tanto, un seguro ecológico) es de interés tanto ecológico como económico.
Consisting of over 1,400 species, bats are the second most diverse group of mammals. Many species are currently threatened, while another ∼244 species are currently listed as Data Deficient by International Union for Conservation Science (IUCN) Global Red List. IUCN assessments can be vital for early conservation intervention and would be aided by a rapid preliminary tool to determine priority for further research and full IUCN Red List assessments. While some tools currently exist to generate extinction risk predictions for bats, they generally require difficult to obtain data, such as phylogenies and trait data. New approaches exist that utilize machine learning algorithms, such as random forest and neural networks, and can accomplish the same task using easier to obtain occurrence-derived data. Here, I fit models that can predict a species' potential IUCN Red List category using prior assignments (critically endangered, endangered, vulnerable, near threatened, and least concern) grouped into binary categories of “Not Threatened” and “Threatened” as training data and applied the best approach to some Data Deficient bat species. These classifications can be used to prioritize investments in conservation for these species. Methods used included index-based approaches (ConR and rCat) and machine learning (IUC-NN and random forest). The best performing model used a random forest algorithm and could accurately predict IUCN binary categories (“Threatened” and “Not Threatened”) 86.9% of the time. While the overall accuracy is similar to the other approaches used here, it vastly outperforms when looking at other metrics like false-negative rate (incorrectly listing a “Threatened” species as “Not threatened”). As a result, this approach could be used as a first step to predict possible IUCN categories for bats that could be used to prioritize conservation research and is not a replacement for full IUCN Global Red List assessment into extinction risk categories.
The genus Myotis comprises a diverse group of vespertilionid bats with worldwide distribution. Twenty-eight Neotropical species are currently recognized. In this study, we evaluate molecular and morphological variation in the M. keaysi complex, a high elevation clade of Neotropical myotine bats characterized by complex taxonomy and high morphological variation. A phylogeny inferred with cytochrome-b sequences recovered two clades composed of samples traditionally assigned to M. keaysi, with 9% of genetic divergence between them. These clades were also suggested as putative distinct species by molecular species delimitation methods. Qualitative and quantitative morphological analyses indicated a phenotypic discontinuity between specimens from central Andes (including the holotype of M. keaysi) and western lowlands of Ecuador, showing strong congruence between molecular and morphological approaches. We therefore describe a new species for the Tumbes-Choco-Magdalena region, documenting their external and cranial diagnostic characters by comparing them with other Neotropical species. In addition, we provide an emended diagnosis for our new concept of M. keaysi.
El género Myotis comprende un grupo diverso de murciélagos vespertiliónidos de distribución mundial. Actualmente se reconocen veintiocho especies neotropicales. En este estudio evaluamos la variación molecular y morfológica del complejo M. keaysi, un clado de alta elevación topográfica?de murciélagos neotropicales caracterizados por una taxonomía compleja y una alta variación morfológica. La filogenia inferida a partir de secuencias de citocromo-b recuperó dos clados en base a muestras tradicionalmente asignadas a M. keaysi, con un 9% de divergencia genética entre sí. Ambos clados también se sugieren como especies putativas distintas mediante métodos de delimitación de especies moleculares. Los análisis morfológicos cualitativos y cuantitativos indicaron una discontinuidad fenotípica entre especímenes de los Andes centrales (incluido el holotipo de M. keaysi) y las tierras bajas occidentales de Ecuador, mostrando una marcada congruencia entre perspectivas moleculares y morfológicas. Por lo tanto, describimos una nueva especie para la región Tumbes-Choco-Magdalena, documentando caracteres diagnósticos externos y craneales por medio de comparaciones con otras especies neotropicales. Además, proporcionamos un diagnóstico modificado para el nuevo concepto de M. keaysi que proponemos
Knowledge of population biological parameters can contribute to assessing the resilience of a population in the face of increasing anthropogenic pressures. Southern Hemisphere long-finned pilot whales (Globicephala melas edwardii) are susceptible to high rates of live stranding-related mortality. However, the biological parameters of this population largely are unknown. In this study, age, growth, allometry, and sexual dimorphism are described using teeth and external body measurements obtained from 515 male, 776 female, and 229 individuals of unknown sex, stranded on the New Zealand coastline between 1948 and 2017. Maximum ages of 31 and 38 years were estimated for males (n = 163) and females (n = 239), respectively. Females ranged in length from 160 to 500 cm (modal size class 400–449 cm) and males from 165 to 622 cm (modal size class 500–549 cm). Length-at-birth for both sexes was estimated at 170 cm using a logistic regression model. Growth models for both sexes indicated a preliminary rapid growth phase followed by a second phase of slower growth. For males, a two-phase growth model also indicated a moderate growth spurt around the average age at attainment of sexual maturity (ca.12–13 years). Asymptotic lengths were estimated at 570 and 438 cm for males and females, respectively. We found strong evidence of sexual size dimorphism, with males significantly larger than females for 13 of 14 external measurements. We also found sexual dimorphism with respect to shape, with males having proportionally longer pectoral fins, wider tail flukes, and taller dorsal fins, than females. Estimates of length-at-birth, maximum ages, and sexual shape dimorphism for G. m. edwardii differed from those previously reported for the North Atlantic subspecies (G. m. melas), which may indicate subspecies or population-level differences in morphology, longevity, and sociality.
For humpback whales, the mother–calf pair is the only stable social unit with calves following their mother after birth and staying in close proximity. This following strategy ensures the maintenance of such close proximity between the mother and her calf, with calves benefiting from maternal protection and care. Using multi-sensor tags, we recorded the diving behavior of calves at three different age-classes (C1, C2, C3) to assess how calves developed in their natural environment at an early stage of their life. From 29 deployments on calves, we extracted the diving metrics from two C1 neonate calves, eight C2 calves, and 19 C3 calves, and we found that some diving metrics (dive duration, time at bottom, maximal depth, or maximal dive duration) differed among calves' age-classes. On 23 tagged mothers, we analyzed if their diving profiles also varied depending on calf's age-class. We showed that only two dive metrics of mothers varied with the age of their own calves (time spent at the bottom, and time interval between dives), but all others were not reliant on the calf's age. Simultaneous deployments on seven mother–calf pairs in 2016 and 2017 revealed highly synchronized dives, with mothers leading the diving pattern. This work represents an extensive study investigating the diving behavior in humpback whale mother–calf pairs on their breeding ground.
Rapid range expansion of boreal forest predators onto the tundra may disrupt local ecological processes, notably through competition with ecologically similar species. Red foxes (Vulpes vulpes) have expanded their range northwards throughout the Canadian Arctic, inducing competition with endemic Arctic foxes (V. lagopus). We studied competition between Arctic and red foxes, with a focus on interference competition, and winter movements of red foxes using satellite telemetry and den occupancy data from both species. We worked at Bylot Island (Nunavut) and Herschel Island (northern Yukon), two sites at the northern limit of the red fox's range. As expected, red fox home ranges were 56% larger on average than Arctic fox home ranges. However, red foxes did not exclude Arctic foxes regionally nor did they prevent them from breeding successfully in their vicinity. On Bylot Island, Arctic foxes did not spatially avoid red foxes more than their conspecifics, as evidenced by similar intra- and interspecific home-range overlaps. On Herschel Island, the red fox pair's home range extensively overlapped the home range of their Arctic fox neighbors. While red foxes tracked on Bylot Island survived several winters without expanding or leaving their home ranges, those on Herschel Island moved onto the sea ice and died. Overall, our results demonstrate low levels of interference competition between the two species in the High Canadian Arctic. When red fox density is low, as in our study areas where land protection prevents predator subsidization by anthropogenic food sources, Arctic and red foxes may be able to co-exist with limited antagonistic interactions. Our sample sizes were limited by the naturally low density of red foxes at their northernmost edge. Replication therefore is needed to fully understand winter space use and intraguild interactions in this species at its northern range limit.
L'expansion rapide de l'aire de répartition des prédateurs de la forêt boréale vers la toundra risque de perturber plusieurs processus écologiques locaux, notamment par le biais d'une compétition accrue entre espèces écologiquement similaires. Le renard roux (Vulpes vulpes) a étendu son aire de répartition vers le nord à travers tout l'Arctique canadien, induisant une compétition avec une espèce endémique, le renard arctique (V. lagopus). Nous avons étudié la compétition entre ces deux espèces, principalement la compétition par interférence, ainsi que les déplacements hivernaux des renards roux, à deux sites situés à la limite nordique de l'aire de répartition du renard roux. Nous avons combiné des données de télémétrie satellitaire et d'occupation des tanières des deux espèces étudiées à l'île Bylot (Nunavut) et à l'île Herschel (nord du Yukon). En accord avec nos prédictions, les domaines vitaux des renards roux étaient en moyenne 56 % plus grands que ceux des renards arctiques. Cependant, les renards roux n'ont pas exclu les renards arctiques des régions utilisées et ne les ont pas empêchés de se reproduire avec succès. À l'île Bylot, un chevauchement similaire des domaines vitaux au sein et entre les espèces indiquait que les renards arctiques n'évitaient pas les renards roux plus que leurs propres congénères. À l'île Herschel, le domaine vital du couple de renards roux chevauchait largement celui des renards arctiques voisins. Alors que les renards roux de l'île Bylot ont survécu plusieurs hivers sans agrandir ou quitter leur domaine vital, ceux de l'île Herschel se sont dispersés sur la banquise et sont morts. Dans l'ensemble, nos résultats démontrent un faible niveau de compétition par interférence entre ces deux espèces dans l'Arctique canadien. Dans nos aires d'étude, la protection du territoire empêche l'apport de nourriture d'origine anthropique qui pourrait soutenir des prédateurs. Lorsque la densité de renards roux est faible, les renards arctiques et roux pourraient coexister sans fortes interactions antagonistes. Nos tailles déchantillons étaient limitées par la faible densité de renards roux à leur limite septentrionale. Il faudra donc répliquer cette étude pour bien comprendre l'utilisation de l'espace en hiver et les interactions intraguildes du renard roux au nord de sa limite de répartition.
Pelt color serves many functions from signaling to crypsis to thermoregulation and its purpose has been a lively source of debate in biology for over a century. Determining the effects of both habitat and human influences on pelt color patterns can be difficult. We made novel use of a multispecies occupancy model by defining “pelt color” as “species.” We then used this model to test predictions and estimate pelt color patterns concurrently for three carnivore species in Idaho, United States. We predicted pelt patterns of all three carnivores would be affected by environmental variables as well as human disturbance. Areas of Idaho where baiting was allowed and preferential harvest possible did not explain pelt patterns in black bears and neither did forest cover. Road density was positively associated with detection probability but negatively associated with occupancy of both black and brown pelt bears, however. Gray pelt wolves were found more often in areas with higher road densities than black wolves. As predicted, black, but not gray, wolves were positively associated with forest cover. Both red and black pelt foxes were positively associated with increasing elevation and road density. Black pelt foxes were negatively associated with forest cover, mirroring the habitat use described for native black pelt foxes. We demonstrate how using noninvasively collected data and extending multispecies occupancy models can allow biologists to study the distribution of different pelt colors in wild populations.
Animals that succeed as non-native species may have highly plastic characteristics. We conducted a radio telemetry survey for introduced masked palm civets (Paguma larvata), which inhabit rural landscapes in almost all of Japan, to clarify their habitat selection and intraspecific variation. We compared two generalized linear mixed models, one that did not consider individual differences and another that did, which indicated the importance of incorporating individual differences for evaluating habitat selection by this species. We obtained results of habitat selectivity for all individuals (i.e., common effect on the species) and for each individual using coefficients of fixed effects or fixed effects with random effects. Masked palm civets significantly selected deciduous broadleaved forests, artificial structures, rice fields, and orchards as a common effect for all individuals. However, these habitats were not necessarily selected as a significant effect for each individual. Deciduous broad-leaved forests and artificial structures were more important than other habitats. The wide range of possible environments and the plasticity of habitat selection shown in this study may partly explain the success of this species in expanding its distribution in Japan.
Mammalian carnivore diversity within the Reserva Natural del Bosque Mbaracayú in eastern Paraguay is represented by five families (Canidae, Mephitidae, Mustelidae, Procyonidae, and Felidae) and includes large-bodied, apex predators, several omnivores, and numerous mesocarnivores. The competitive exclusion principle argues that sustained spatial and temporal coexistence of two or more species with identical ecological requirements is unsustainable. The Reserve is a mosaic of habitats that has become isolated due to extensive deforestation of the surrounding Upper Paraná Atlantic Forest. Nevertheless, it is remarkable in that 16 mammalian carnivore species are documented as coexisting within the Reserve. We sought to determine the extent to which this diverse community is mitigating competition through the partitioning of available niche space by assessing dietary ecology of mammalian carnivores present, including diet breadths and dietary overlap, and by examining spatial patterns within the reserve. Feces were collected from all 16 mammalian carnivore species from seven areas within the reserve and specific identifications were confirmed by molecular analyses. Diet breadth, , standardized diet breadth, , and Pianka's Index for dietary overlap, Ô, were calculated. A Chi-square goodness-of-fit test was performed to test for randomness of samples associated with survey areas. Diet analyses indicated a spectrum from dietary generalists to specialists. Species segregated into six dietary guilds, defined as groups of species with Ô > 0.5. Four guilds included only one species each (Neotropical otter, crab-eating fox, jaguar, and puma). The low dietary overlap between jaguar and puma contrasts with studies conducted elsewhere. One guild consisted of four highly omnivorous species (maned wolf, Molina's hog-nosed skunk, crab-eating raccoon, and South American coati). The sixth guild included eight species which mostly consumed small vertebrates, primarily mammals as well as birds and reptiles (bush dog, two mustelines, five small felids). The mustelines (tayra and lesser grison) had extremely high dietary overlap. Although they did not segregate spatially, they are known to occupy distinct niches in vertically stratified forests. The five small felids also showed extremely high dietary overlap. Three of them were found to segregate spatially within the Reserve and two did not, although one (jaguarundi) is known to segregate temporally, being more active diurnally. The exceptionally rich community of mammalian carnivore species at the Reserva Natural del Bosque Mbaracayú appeared to avoid unsustainable competition by a variety of mechanisms, some utilizing different food items, or, in the case of high dietary overlap, utilizing spatial or temporal resources differently.
La diversidad de mamíferos carnívoros dentro de la Reserva Natural del Bosque Mbaracayú, en el este de Paraguay, está representada por cinco familias (Canidae, Mephitidae, Mustelidae, Procyonidae y Felidae) e incluye depredadores tope de gran tamaño, varios omnívoros y numerosos mesocarnívoros. El principio de exclusión competitiva propone que es insostenible la coexistencia de dos o más especies con requerimientos ecológicos idénticos. La Reserva Natural del Bosque Mbaracayú está compuesta por un mosaico de hábitats que han quedado aislados debido a la extensa deforestación del Bosque Atlántico del Alto Paraná circundante. A pesar de eso, es notable que esté documentada la coexistencia de 16 especies de mamíferos carnívoros dentro de la reserva. Buscamos determinar hasta qué punto esta comunidad diversa está mitigando la competencia a través de la división del espacio de nicho disponible mediante la evaluación de la ecología trófica de los mamíferos carnívoros presentes, incluyendo la amplitud y la superposición de las dietas y examinando los patrones espaciales dentro de la reserva. Se recolectaron heces de las 16 especies de mamíferos carnívoros en siete áreas dentro de la reserva y las identificaciones específicas se confirmaron mediante análisis moleculares. Se calcularon la amplitud de la dieta, ; la amplitud de la dieta estandarizada, ; y, el índice de Pianka para la superposición de la dieta, Ô. Se realizó una prueba de bondad de ajuste de Chi-cuadrado para probar la aleatoriedad de las muestras asociadas con las áreas de muestreo. Los análisis de la dieta indican un espectro que va desde generalistas hasta especialistas. Las especies están segregadas en seis gremios tróficos, definidos como grupos de especies con Ô > 0.5. Cuatro gremios incluyeron solo una especie (nutria neotropical, zorro cangrejero, jaguar y puma). La baja superposición de la dieta entre el jaguar y el puma contrasta con estudios realizados en otros lugares. Un gremio consistió en cuatro especies altamente omnívoras (aguar aguazú, zorrino chileno, mayuato y coatí rojo). El sexto gremio incluyó ocho especies que mayormente consumieron pequeños vertebrados, principalmente mamíferos así como aves y reptiles (zorro vinagre, dos mustélidos y cinco pequeños felinos). Los mustélidos (taira y grisón chico) tuvieron una alta superposición de la dieta. Aunque no se separaron espacialmente, estas especies son conocidas por ocupar diferentes nichos en bosques estratificados. Los cinco felinos pequeños también mostraron alta superposición de la dieta. Se encontró que tres de ellas se segregaron espacialmente dentro de la reserva y dos no, aunque una (yaguarundi) es conocida por segregarse temporalmente, siendo más activa durante el día. La excepcionalmente rica comunidad de especies de mamíferos carnívoros de la Reserva Natural del Bosque Mbaracayú parecen evitar una competencia insostenible con una variedad de mecanismos, algunos utilizando los alimentos de manera diferente o, en el caso de una gran superposición de la dieta, utilizando los recursos espaciales y temporales de manera diferente.
The ocelot (Leopardus pardalis) is a widely distributed, medium-sized felid in the Americas with declining population size. We estimated ocelot densities and home ranges in one agricultural area in the Magdalena River valley in Colombia, a private reserve and cattle ranch in the Colombian Llanos, and a private reserve in the Serra do Amolar in the Brazilian Pantanal. We used camera trapping (39–52 stations) and spatially explicit capture-recapture (SECR) models. Density estimates (individuals/100 km2) were 11.0 ± 2.7 (SE) in the Magdalena River valley; 13.2 ± 3.2 (SE) in the Llanos, and 10.3 ± 2.9 (SE) in the Serra do Amolar. Overall, despite an impact of agriculture and human disturbance, our results highlight the importance of unprotected areas and privately protected ranching areas for ocelot conservation. As agriculture continues to expand across the tropics causing habitat loss, and negatively affecting ocelot densities, we recommend land use planning and best agricultural practices to maintain natural habitats, thereby limiting human impacts on ocelot conservation.
El ocelote (Leopardus pardalis) es un felino de tamaño mediano ampliamente distribuido en las Américas con un tamaño de población descendente. Estimamos las densidades del ocelote y sus áreas de acción en una zona agrícola en el valle del río Magdalena en Colombia, una reserva privada y rancho ganadero en los Llanos colombianos, y una reserva privada en la Serra do Amolar en el Pantanal brasileño. Usamos cámaras trampa (39–52 estaciones) y modelos de captura-recaptura espacialmente explícitos (SECR). Las densidades estimadas (individuos/100 km2) fueron de 11.0 ± 2.7 (SE) en el valle del río Magdalena, 13.2 ± 3.2 (SE) en los Llanos, y 10.3 ± 2.9 (SE) en la Serra do Amolar. En general, a pesar del impacto de la agricultura y la perturbación humana, nuestros resultados destacan la importancia de las áreas no protegidas y las áreas ganaderas privadas protegidas en la conservación del ocelote. A medida que la agricultura continúa expandiéndose en los trópicos causando pérdida de hábitat y afectando negativamente las densidades de ocelotes, recomendamos la planificación del uso de la tierra y mejores prácticas agrícolas para mantener los hábitats naturales en dichas áreas, limitando el impacto antrópico sobre la conservación del ocelote.
Rodents of the family Echimyidae present a wide variety of life histories and ecomorphological adaptations. This study evaluated morphological integration patterns, modularity, and evolutionary flexibility in six Echimyid genera representing ecomorphological extremes within the family. The relationships between traits were evaluated by comparing estimated covariance and correlations matrices of populations. The presence of modules was investigated by comparing the patterns of integration between traits and using hypothetical matrices based on shared development/function and masticatory stress. The results point to a common covariance and correlation pattern among the six echimyid genera, suggesting a conserved pattern of covariation (associations among traits) throughout the evolution of this group. The overall magnitude of integration, however, varied greatly. We also found a high degree of modularity in all six echimyid genera. Finally, we observed a clear association between flexibility, i.e., the ability of a species to respond to the direction of selection, with the overall magnitude of integration and degree of modularization. The results of this study provide hypotheses concerning the underlying effects of the association among traits, which may have facilitated or constrained the evolution of morphological variation in the diverse family Echimyidae.
Os roedores da família Echimyidae apresentam uma ampla variedade de histórias de vida e adaptações ecomorfológicas. O objetivo deste estudo foi investigar a variação craniana nesta família, fundamentandose na genética quantitativa e integração morfológica. Nós avaliamos os padrões de integração morfológica, modularidade e flexibilidade em seis táxons de Equimídeos representando extremos ecomorfológicos dentro da família. As relações entre os traços foram avaliadas comparando matrizes de covariância e correlação estimadas para as populações. A presença dos módulos foi investigada comparando os padrões de integração entre os traços e utilizando matrizes hipotéticas baseadas no desenvolvimento/função compartilhado e estresse mastigatório. Os resultados apontam para um padrão de covariância e correlação comum entre os equimídeos, sugerindo um padrão de covariação (associação entre traços) conservado ao longo da evolução desse grupo. A magnitude de integração geral, por outro lado, variou significantemente. Além disso, nós demonstramos que o crânio dos equimídeos é amplamente modular. Finalmente, observamos uma clara associação entre flexibilidade, ou seja, a capacidade de uma espécie em responder na direção da seleção, com a magnitude de integração e o grau de modularização. Os dados obtidos nesse estudo fornecem hipóteses relativas aos efeitos subjacentes da associação entre as características que podem facilitar ou restringir a evolução da variação morfológica na diversa família Echimyidae.
Skeletal injuries, especially broken bones, diminish physical mobility of animals, and they may affect an individual's ability to obtain food and to evade predators. We quantified and compared healed fractures in two sympatric species of tree squirrels (Sciurus nigerLinnaeus, 1758 and S. carolinensisGmelin, 1788) that differ in body size (mass) and locomotor mode. We assessed the number and location of healed fractures in two urban populations of S. carolinensis and in individuals of both species from one rural location. We found a higher-than-expected proportion of healed fractures in older animals of both species. However, we detected no deviations from expected in the number of healed fractures between the two species or between sexes within a species. Urban populations of S. carolinensis exhibited significantly higher-than-expected proportions of healed fractures, and they were approximately 4.5 times more likely to have a healed injury as compared to rural S. carolinensis. Our findings suggest that S. carolinensis in urban populations experience a higher rate of injury and/or a higher rate of survival after injury than those in rural populations.
Pocket gophers provide vital ecosystem services; however, species like the southeastern pocket gopher (Geomys pinetis), endemic to the southeastern United States, are declining. Long-term conservation of this species requires greater understanding of its habitat characteristics. Our objective here was to determine habitat features associated with southeastern pocket gopher occurrence at the local (100 ha) and home-range (0.09 ha) scales. We assessed occurrence and carried out vegetation surveys at 177 sites across the species' range during the growing season (March–September) 2016–2017. At the local scale, we found a negative relationship between occurrence and groundcover height and a quadratic relationship with canopy closure. At the home-range scale, occurrence was positively related to grass groundcover and had a quadratic relationship with canopy closure. Restoration of southeastern pocket gopher habitat should focus on creating or maintaining areas with intermediate canopy (∼45–55%) and an understory dominated by grasses and forbs.
In seasonal environments, the winter months can drive the structure and dynamics of vertebrate communities. Most ecological studies have focused on species above the snow, overlooking those within the subnivium (below-snow environment). The Great Lakes region of North America is characterized by seasonal snow cover and a diverse assemblage of small mammals, both of which are changing rapidly in response to a changing climate. To study the seasonal dynamics of small mammals, we sampled communities in three forest types (hardwood, hemlock-cedar, and spruce bog) in summer and winter over 2 years. We hypothesized that seasonal differences in communities would be moderated by forest structure in summer and snow in winter. We assessed community dominance via species diversity and the abundances of deer mice (Peromyscus maniculatus), white-footed mice (P. leucopus), and southern red-backed voles (Myodes gapperi). We estimated a Community Temperature Index (CTI; a metric of the balance between warm- and cold-adapted species in a community) and tested seasonal drivers of CTI. Species diversity was highest in spruce bogs in winter due to increased species evenness, but diversity was consistent year-round in hardwood and hemlock-cedar forests due to unchanging species dominance. Spruce bogs supported the coldest CTI in summer, but CTIs converged across forest types in winter. In summer, forest structure drove CTI; in winter, colder CTIs were associated with deeper snow and a warmer subnivium. Our work reveals that snow is a critical habitat and filter for cold-adapted species that ultimately structures small mammal communities. Given rapid changes in snow conditions due to climate change, we predict continued range contractions for subnivium-adapted species.
KEYWORDS: Camera trap, capture–recapture, density estimation, detection rate index, fecal pellet count index, Lepus americanus, random encounter model, random encounter and staying time, snowshoe hare, time-to-event
Boreal ecosystems are experiencing extensive changes because of anthropogenic stressors such as climate change. Information on density of species at multiple sites is vital to understand and manage the impact of these changing conditions on boreal forest communities. Yet, for most boreal forest species, including the vast majority of mammals, obtaining reliable estimates of density is exceedingly difficult. Recently developed methods for the estimation of densities of unmarked animals from camera-trapping data could help to overcome this hurdle, but have not yet been empirically validated in many ecosystems. Here, we assess the ability of camera traps to estimate density of snowshoe hare (Lepus americanus) using three different models: the random encounter model (REM), the random encounter and staying time (REST) model, and the time-to-event (TTE) model. We additionally evaluate the relationship between hare density and two simple indices based on camera detection rate and pellet counts. Across 13 sites in North Central Washington, United States, we compared live-trapping spatially explicit capture–recapture (SECR) estimates of density to the three camera-based density models and the two indices. We found that the camera-based models, in particular the REM and REST models, performed well in estimating densities consistent with the live-trapping data, with an average difference in density from SECR-based estimates of only 0.12 and 0.13 hares/ha, respectively. Both indices also had strong predictive relationships with hare density. Our results show that, owing to their noninvasive nature and relative ease of application, camera-based methods could be used to obtain hare density estimates at much larger spatiotemporal scales than have been applied to date. Given the keystone role of hare in boreal ecosystems, and emerging evidence of hare range retraction, the ability to estimate densities across many sites is a key tool for hare conservation and management. Moreover, our results are highly encouraging for the application of camera-based methods to obtain density estimates on a wide variety of boreal forest species, though additional validation will be necessary.
Globally, many wild deer populations are actively studied or managed for conservation, hunting, or damage mitigation purposes. These studies require reliable estimates of population state parameters, such as density or abundance, with a level of precision that is fit for purpose. Such estimates can be difficult to attain for many populations that occur in situations that are poorly suited to common survey methods. We evaluated the utility of combining camera trap survey data, in which a small proportion of the sample is individually recognizable using natural markings, with spatial mark–resight (SMR) models to estimate deer density in a variety of situations. We surveyed 13 deer populations comprising four deer species (Cervus unicolor, C. timorensis, C. elaphus, Dama dama) at nine widely separated sites, and used Bayesian SMR models to estimate population densities and abundances. Twelve surveys provided sufficient data for analysis and seven produced density estimates with coefficients of variation (CVs) ≤ 0.25. Estimated densities ranged from 0.3 to 24.6 deer km–2. Camera trap surveys and SMR models provided a powerful and flexible approach for estimating deer densities in populations in which many detections were not individually identifiable, and they should provide useful density estimates under a wide range of conditions that are not amenable to more widely used methods. In the absence of specific local information on deer detectability and movement patterns, we recommend that at least 30 cameras be spaced at 500–1,000 m and set for 90 days. This approach could also be applied to large mammals other than deer.
Odocoileus virginianus (white-tailed deer) and O. hemionus (mule deer) are sympatric across much of North America. Molecular evidence suggests that up to 24% of individuals in some populations are a product of hybrid ancestry. Several studies have alluded to ancient and recent introgression between Odocoileus spp.; however, no divergence dates were proposed. Herein, phylogenetic analyses of DNA sequences obtained from the mitochondrial Cytochrome b gene in 690 individuals identified three clades corresponding to black-tailed deer, white-tailed deer, or a unique combination of both white-tailed deer and mule deer. White-tailed deer and mule deer diverged from a common ancestor of approximately 3.13 mya followed by an ancient hybridization event of approximately 1.32 mya, in which the white-tailed deer mitochondrial genome was “captured” by mule deer. This hybridization event produced a novel haplogroup for white-tailed deer and mule deer located west of the Appalachian Mountains and east of the Cascade Range, south to Veracruz, Mexico, and north to the Yukon Territory, Canada. The ancestral mule deer-like mitochondrial genome appears to be restricted to black-tailed deer distributed along the western portion of the Cascade and Sierra Nevada Ranges of the United States and Canada, whereas the ancestral white-tailed deer-like mitochondrial genome is restricted to the eastern United States and portions of Latin America and Caribbean regions. The “captured mitochondrial genome” has continued on an independent evolutionary trajectory and represents a unique and broadly distributed haplogroup that is 7.25% and 2.84% different from the ancestral mule deer and ancestral white-tailed deer haplogroups, respectively.
Odocoileus virginianus (ciervo de cola blanca) y O. hemionus (cievo mulo) son simpátricos a lo largo de Norte América. Evidencia molecular sugiere que en algunas poblaciones un 24% de individuos son el producto de linajes híbridos. Varios estudios aluden introgresiones antiguas y recientes entre Odocoileus spp. sin embargo, no proponen fecha de tal divergencia. En este estudio, los análisis filogenéticos de secuencias de ADN obtenidas del gen mitocondrial citocromo-b de 690 individuos, identificaron tres clados que corresponden al ciervo de cola negra, ciervo de cola blanca, o una combinación única de ciervo de cola blanca y ciervo mulo. El ciervo de cola blanca y el ciervo mulo divergieron de un ancestro común hace aproximadamente 2.65 Ma, seguido de un evento antiguo de hibridación hace aproximadamente 1.12 Ma en donde el genoma mitocondrial del ciervo de cola blanca fue “capturado” por el ciervo mulo. Este evento de hibridación produjo un nuevo haplogrupo en el ciervo de cola blanca y en el ciervo mulo localizados al Oeste de las Montañas Apalaches, al Este de las Cordilleras de Cascadas, al Sur de Veracruz, México, y al Norte del Territorio Yukón en Canadá. El genoma mitocondrial y ancestral semejante al ciervo mulo parece estar restringido al ciervo de cola negra que se distribuye a lo largo de la porción Oeste de las Cordilleras Sierras Nevadas y de la Cordillera de Cascadas de los EE. UU. y Canadá; mientras que, el genoma mitocondrial y ancestral semejante al ciervo de cola blanca se restringe al Este de los EE. UU. y partes de las regiones de Latinoamérica y el Caribe. El “genoma mitocondrial capturado” continuó una trayectoria evolutiva independiente y representa un único haplogrupo distribuido ampliamente siendo 7.25% y 2.84% diferente del haplogrupo del ancestro del ciervo mulo y del ancestro del ciervo de cola blanca respectivamente.
Management of rangelands requires knowledge of forage species that are preferred or avoided by wildlife and livestock. A recent expansion of woody vegetation into previously open grasslands in African savanna ecosystems negatively impacts many mammalian grazers. Nevertheless, the ecological role of bush encroacher plant species as food may present a benefit for browsing species. We quantified diet selection by Masai giraffes (Giraffa camelopardalis tippelskirchi) through foraging observations and vegetation sampling in the Tarangire Ecosystem of Tanzania, which includes large areas of a native shrub that livestock managers have classified as an encroacher species (Dichrostachys cinerea). We compared woody plant species used by giraffes for foraging with availability at two different spatial scales during the wet and dry seasons. Giraffes selected some woody plants such as Vachellia species while significantly avoiding others, both at the local and landscape scales. Giraffes preferred foraging on D. cinerea at both spatial scales and in both the wet and dry seasons. Management that has focused on benefiting grazing livestock by removal of encroaching species (e.g., D. cinerea) may have unintended consequences for wildlife, especially for browsing species like giraffes that feed extensively on the expanding bush species.
Beatriz Lopes, John F. McEvoy, Ronaldo Gonçalves Morato, Hermes R. Luz, Francisco B. Costa, Hector Ribeiro Benatti, Thiago da Costa Dias, Vlamir José Rocha, Vanessa do Nascimento Ramos, Ubiratan Piovezan, Patricia Ferreira Monticelli, Ana Maria Nievas, Richard Campos Pacheco, Maria Estela Gaglianone Moro, Jardel Brasil, Peter Leimgruber, Marcelo B. Labruna, Katia Maria Paschoaletto Micchi de Barros Ferraz
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