RESUMO

Monitoring the invasive exotic species and their effect on native fauna is fundamental for their effective control. The objective of this research is to evaluate the spatiotemporal distribution and overlap of medium-large-sized fauna in El Palmar National Park, Argentina, to consider potential negative interactions between native and exotic species. Camera traps were distributed in 27 sites between 2017 and 2019. Spatial and temporal overlap was estimated for every pair of exotic-native taxa. With 2673 camera days, two exotic and seven native taxa were recorded. All species were distributed along the extension of the National Park but in different numbers of sites. Exotic axis deer (Axis axis) was recorded in all sites but one, and exotic wild boar (Sus scrofa) occurred at only one-third of the sites surveyed. The occurrence of native mammals ranged between 26% (Geoffroy's cat, Leopardus geoffroyi) and 67% (capybara, Hydrochoerus hydrochaeris). Spatial overlap between native and exotic species was high overall and was higher in winter when species moved over larger areas to look for limited resources. Except for greater rhea (Rhea americana), which was diurnal, all species had crepuscular or nocturnal patterns. Both exotic species had an intermediate/high overlap in their activity pattern with almost all native species, including some species with similar diets, but the hours of their maximum activities did not strictly coincide. However, the existence of differences in the exotic species' activity patterns compared to their patterns in other areas where they inhabit could indicate segregation in daily activity to relax competition.

RESUMO

Abstract Introduction: Resource partitioning by promoting coexistence is essential to determine species richness and composition in natural communities. However, the partitioning of time has been questioned as a mechanism that promotes the coexistence of ecologically similar species. Objective: To determine the importance of the partitioning of time as a mechanism that promotes coexistence, we compared the activity patterns of tropical frugivorous bats. Methods: We captured bats with mist nets from sunset to sunrise in three study sites (tropical dry forest, wet forest, and rainforest) to calculate activity patterns of the species using Kernel density estimation. We used the superposition coefficient (Δ1) to compare activity patterns between (1) bat assemblages of study sites, (2) frugivorous species in the same site, and (3) populations of the same species among different sites. To determine whether the overlap in the activity patterns was related to the ecological similarity of species, we evaluated the association between Δ1 and similarity in abundances and body mass and phylogenetic closeness. Results: We found geographical variations in the overall activity patterns of the assemblages of the three localities. Likewise, we found variations in activity patterns between species at each study site and between populations in different study sites. Overlap in activity patterns tended to decrease as species were phylogenetically more closely related and similar in abundance and body size. Conclusions: Our results provide empirical support for the role of temporal segregation in activity patterns as a mechanism that promotes the coexistence of ecologically similar species in nature.

Resumen Introducción: La partición de recursos es esencial para determinar la riqueza y composición de especies en las comunidades naturales. Sin embargo, la segregacion temporal ha sido cuestionada como un mecanismo que promueve la coexistencia de especies ecológicamente similares. Objetivo: Con el fin de determinar la importancia de la segregación en los patrones de actividad, como mecanismo que promueve la coexistencia; se compararon los patrones de actividad de murciélagos frugívoros neotropicales. Métodos: Se capturaron murciélagos con redes de niebla desde el atardecer hasta el amanecer en tres localidades (bosque seco tropical, bosque muy húmedo y bosque lluvioso submontano) con el fin de calcular los patrones de actividad de las especies empleando la estimación de densidad Kernel. Se utilizó el coeficiente de superposición (Δ) para comparar patrones de actividad entre: (1) ensamblajes de murciélagos de los sitios de estudio, (2) especies frugívoras en el mismo sitio, y (3) poblaciones de la misma especie en diferentes sitios. Resultados: Se encontraron variaciones geográficas en los patrones de actividad de los ensamblajes en las tres localidades. Asimismo, se encontraron variaciones en los patrones de actividad entre especies en cada sitio y entre poblaciones en diferentes sitios. Determinamos que la superposición en los patrones de actividad disminuyó a medida que las especies estaban más relacionadas filogenéticamente, similares en abundancia y tamaño corporal; lo que sugiere una tendencia hacia la segregación temporal de especies ecológicamente similares. Conclusión: Estos resultados proveen apoyo empírico del papel de la segregación temporal en los patrones de actividad como un mecanismo que promueve la coexistencia de especies ecológicamente similares en la naturaleza.

Assuntos

RESUMO

Inbreeding costs can be high in haplodiploid hymenopterans due to their particular mechanism of sex determination (i.e., single-locus complementary sex-determination system, sl-CSD), as it can lead to the production of sterile males. Therefore, mechanisms contributing to reduced inbred matings can be beneficial. In this sense, asynchronous nest departure of sibling drones and gynes could reduce kin encounters in social hymenopterans. Using six observation colonies, we determined under field conditions the nest departure behaviour of sibling reproductives of the social wasp Vespula germanica (Hymenoptera: Vespidae). We determined that sexuals leave the nests definitively and detected asynchronous departure not fixed to a particular caste at a seasonal scale in some colonies, as gynes or drones delayed their departure as a function of the departure of the opposite sex, depending on the colony. At a higher temporal resolution (i.e., within a day), we discovered that drones consistently began to leave nests 1 h before gynes and this difference was driven by those individuals that left on the same day as did the opposite-sex kin. Even though other mechanisms such as polyandry and differential dispersal could also be important at reducing inbred matings in the species, the observed departure patterns (i.e., in some colonies actually leave together with the opposite caste, while in others temporal segregation seems to occur) from nests could be complementary to the former and be important at reducing the negative effects of inbreeding in this invasive species.

Assuntos

RESUMO

Temporal niche shifts can shape predator-prey interactions by enabling predator avoidance, enhancing feeding success, and reducing competition among predators. Using a community-based conservation approach, we investigated temporal niche partitioning of mammalian predators and prey across 12 long-term camera trap surveys in the Pacific slope and Talamanca Cordillera of Costa Rica. Temporal overlap and segregation were investigated between predator-prey and predator-predator pairs using overlap analysis, circular statistics, and relative abundance after accounting for differences in habitat, season, and human impact among sites. We made the assumption that predators select abundant prey and adjust their activity to maximize their temporal overlap, thus we predicted that abundant prey with high overlap would be preferred prey species for that predator. We also predicted that similar-sized pairs of predator species with the greatest potential for competitive interactions would have the highest temporal segregation. Our results supported the existence of temporal niche separation among the eight species of predators-the smaller Leopardus felids (ocelot, margay, oncilla) were primarily nocturnal, the largest felids (jaguar and puma) and coyote were cathemeral, and the smaller jaguarundi and tayra were mostly diurnal. Most prey species (67%) were primarily nocturnal versus diurnal or cathemeral (33%). Hierarchical clustering identified relationships among species with the most similar activity patterns. We discuss the primary prey and competitor species predicted for each of the eight predators. Contrary to our prediction, the activity pattern of similar-sized intraguild competitors overlapped more than dissimilar-sized competitors, suggesting that similar-sized predators are hunting the same prey at the same time. From this we conclude that prey availability is more important than competition in determining circadian activity patterns of Neotropical predators. Our results indicate the presence of a delicate balance of tropical food webs that may be disrupted by overhunting, leading to a depauperate community consisting of ubiquitous generalists and endangered specialists. With Central America a hotspot for hunting-induced "empty forests," community-based conservation approaches may offer the best road to reduce illegal hunting and maintain the biodiversity and community structure of tropical forest systems.

Los cambios temporales de nicho pueden amoldar las interacciones predador-presa al permitir a la presa evadir los predadores, mejorar la eficacia de la alimentación y reducir la competición entre predadores. Mediante muestreos con cámaras trampa en 12 sitios de la pendiente del Pacífico y la Cordillera de Talamanca de Costa Rica, investigamos la división temporal de los nichos de mamíferos predadores y presas usando un enfoque de conservación basado en la comunidad. Investigamos la superposición y segregación temporal entre pares predador-presa y predador-predador utilizando análisis de superposición, estadísticas circulares y abundancia relativa, teniendo en cuenta diferencias de hábitat, estacionales y de impacto humano entre los sitios. Asumimos que los predadores seleccionan presas abundantes y ajustan su actividad para maximizar su superposición temporal con éstas; por lo tanto, predijimos que una presa abundante con alta superposición sería una especie de presa preferida para ese predador. También predijimos que pares de especies de predadores de tamaño similar con el mayor potencial para interacciones competitivas tendrían la mayor segregación temporal. Nuestros resultados respaldaron la existencia de una separación temporal de nicho entre las ocho especies de predadores­determinamos que los felinos más pequeños del género Leopardus (manigordo, caucel, tigrillo) son principalmente nocturnos, los felinos más grandes (jaguar y puma) y el coyote son catemerales, y los jaguarundi y tayra más pequeños son principalmente diurnos. La mayoría de las especies de presas (67%) son principalmente nocturnas versus diurnas o catemerales (33%). Mediante análisis de agrupación jerárquica, identificamos relaciones entre especies con los patrones de actividad más similares. Para cada uno de los predadores discutimos las presas primarias predichas y las especies competidoras. Contrario a nuestra predicción, el patrón de actividad de los predadores intragremios de tamaño similar se superpone más que el de los competidores de distinto tamaño, lo que indica que los predadores de tamaño similar están cazando la misma presa y están activos al mismo tiempo. De esto concluimos que la disponibilidad de presas es más importante que la competición en cuanto a determinar los patrones de actividad circadiana de los predadores neotropicales. Nuestros resultados revelan que el delicado equilibrio de las redes tróficas tropicales puede ser interferido por la caza excesiva, lo que lleva a una comunidad depauperada compuesta por generalistas ubicuos y especialistas en peligro de extinción. Con América Central como un centro de "bosques vacíos" inducidos por la caza, los enfoques de conservación basados en la comunidad pueden ofrecer el mejor camino para reducir la caza ilegal, y mantener la biodiversidad y estructura ecológica comunitaria de los sistemas forestales tropicales.

RESUMO

Camera traps were used to study the daily activity patterns of medium and large mammals (> 1 kg) in an area of Mixed Rain Forest (High Altitude Atlantic Forest) in the South of Brazil. These mammals are adapted to humid forest environments and exhibit seasonal behavior that is different to that of neotropical mammals living in tropical environments. Camera traps without bait were active day and night and through all seasons during the period from March 1999 to December 2010, with a sampling effort of 11,431 trap-days. Species that exhibited diurnal tendencies were Dasyprocta azarae, Eira barbara, Nasua nasua and Puma yagouaroundi. The nocturnal species observed were Dasypus novemcinctus, Tamandua tetradactyla and Procyon cancrivorus. Didelphis aurita, Leopardus pardalis and L. wiedii exhibited nocturnal tendencies. Cerdocyon thous tended to be more crepuscular than nocturnal. Puma concolor exhibited a tendency to nocturnal and crepuscular activity, but diurnal activity was also observed. Finally, the species Mazama gouazoubira and Leopardus tigrinus were defined as cathemeral. While many species exhibited a tendency for the majority of their activity to be concentrated at certain times, there was no time during which medium and large mammal activity entirely ceased, demonstrating a balanced daily distribution of activity in a Mixed Rain Forest. There were differences in activity patterns between different seasons, especially between summer and winter, with nocturnal species exhibiting a tendency to more intense activity during the first half of the night during the winter and diurnal species tending to be more active at the end of the day during the same season.(AU)

Mamíferos de médio e grande porte (> 1 kg) foram estudados para detecção de padrões de atividade diária em área de Floresta Ombrófila Mista (Floresta Atlântica de altitude) no sul do Brasil. Estes mamíferos adaptados a ambiente de floresta úmida em clima subtropical possuem comportamentos sazonais diferenciados de mamíferos neotropicais vivendo em ambientes tropicais. Armadilhas fotográficas permaneceram em atividade sem utilização de iscas, durante dia e noite ao longo de todas as estações do ano no intervalo entre março de 1999 e dezembro de 2010 com esforço amostral de 11.431 armadilhas-dia. As espécies com tendência diurna foram Dasyprocta azarae, Eira barbara, Nasua nasua e Puma yagouaroundi. As espécies noturnas foram Dasypus novemcinctus, Tamandua tetradactyla e Procyon cancrivorus. As espécies com tendência noturna foram Didelphis aurita, Leopardus pardalis e L. wiedii. Cerdocyon thous apresentou tendência mais crepuscular do que noturna. Puma concolor mostrou tendência noturna a crepuscular e com ocorrência de atividades diurnas. As espécies Mazama gouazoubira e Leopardus tigrinus foram consideradas catemerais. Apesar de as diversas espécies, em sua maioria, apresentarem tendência de concentração de atividade em determinados horários, não houve nenhum horário sem atividade de mamíferos de médio e grande porte, demonstrando equilíbrio de distribuição de atividade ao longo do dia em Floresta Ombrófila Mista. Houve diferenças nos padrões de atividade entre diferentes estações, especialmente entre verão e inverno, com espécies noturnas mostrando tendência a maior atividade durante a primeira metade da noite durante o inverno, enquanto espécies diurnas tenderam a ser mais ativas no final do dia durante esta estação.(AU)

Assuntos

RESUMO

Camera traps were used to study the daily activity patterns of medium and large mammals (> 1 kg) in an area of Mixed Rain Forest (High Altitude Atlantic Forest) in the South of Brazil. These mammals are adapted to humid forest environments and exhibit seasonal behavior that is different to that of neotropical mammals living in tropical environments. Camera traps without bait were active day and night and through all seasons during the period from March 1999 to December 2010, with a sampling effort of 11,431 trap-days. Species that exhibited diurnal tendencies were Dasyprocta azarae, Eira barbara, Nasua nasua and Puma yagouaroundi. The nocturnal species observed were Dasypus novemcinctus, Tamandua tetradactyla and Procyon cancrivorus. Didelphis aurita, Leopardus pardalis and L. wiedii exhibited nocturnal tendencies. Cerdocyon thous tended to be more crepuscular than nocturnal. Puma concolor exhibited a tendency to nocturnal and crepuscular activity, but diurnal activity was also observed. Finally, the species Mazama gouazoubira and Leopardus tigrinus were defined as cathemeral. While many species exhibited a tendency for the majority of their activity to be concentrated at certain times, there was no time during which medium and large mammal activity entirely ceased, demonstrating a balanced daily distribution of activity in a Mixed Rain Forest. There were differences in activity patterns between different seasons, especially between summer and winter, with nocturnal species exhibiting a tendency to more intense activity during the first half of the night during the winter and diurnal species tending to be more active at the end of the day during the same season.

Mamíferos de médio e grande porte (> 1 kg) foram estudados para detecção de padrões de atividade diária em área de Floresta Ombrófila Mista (Floresta Atlântica de altitude) no sul do Brasil. Estes mamíferos adaptados a ambiente de floresta úmida em clima subtropical possuem comportamentos sazonais diferenciados de mamíferos neotropicais vivendo em ambientes tropicais. Armadilhas fotográficas permaneceram em atividade sem utilização de iscas, durante dia e noite ao longo de todas as estações do ano no intervalo entre março de 1999 e dezembro de 2010 com esforço amostral de 11.431 armadilhas-dia. As espécies com tendência diurna foram Dasyprocta azarae, Eira barbara, Nasua nasua e Puma yagouaroundi. As espécies noturnas foram Dasypus novemcinctus, Tamandua tetradactyla e Procyon cancrivorus. As espécies com tendência noturna foram Didelphis aurita, Leopardus pardalis e L. wiedii. Cerdocyon thous apresentou tendência mais crepuscular do que noturna. Puma concolor mostrou tendência noturna a crepuscular e com ocorrência de atividades diurnas. As espécies Mazama gouazoubira e Leopardus tigrinus foram consideradas catemerais. Apesar de as diversas espécies, em sua maioria, apresentarem tendência de concentração de atividade em determinados horários, não houve nenhum horário sem atividade de mamíferos de médio e grande porte, demonstrando equilíbrio de distribuição de atividade ao longo do dia em Floresta Ombrófila Mista. Houve diferenças nos padrões de atividade entre diferentes estações, especialmente entre verão e inverno, com espécies noturnas mostrando tendência a maior atividade durante a primeira metade da noite durante o inverno, enquanto espécies diurnas tenderam a ser mais ativas no final do dia durante esta estação.

Assuntos

RESUMO

The communities of anuran amphibians, especially in tropical regions, are directly influenced by environmental conditions, whfich play an important role in structuring and regulating communities. This study aimed to determine the diversity of reproductive modes, season of vocalization and to test correlation among climatic variables and richness, abundance of adult frogs and tadpoles, and activity of vocalization of males in 12 water bodies located in and around the Emas National Park, southwestern state of Goiás, Brazil. Sixteen samples were carried out between December 2005 and March 2008. A total of 25 species from five families were recorded: Bufonidae (one species), Hylidae (nine species), Leptodactylidae (eight species), Leiuperidae (six species) and Microhylidae (one species). Four patterns of reproductive activity were recognized among the species: continuous, intermediate, long and explosive. The richness of adult frogs, the abundance and activity of the calling males were positively related to air temperature, humidity and precipitation. The richness of tadpoles was positively related to precipitation and water temperature, but there was no relationship between the abundance of tadpoles with no descriptors of climate. Six reproductive modes were recorded, 56% of species had widespread aquatic reproductive modes (mode 1 and 4) and 44% deposit eggs in nests of foam (modes 11, 13, 30 and 32). The species recorded in this study showed a predominance of reproductive modes and general reproductive pattern typically associated with the warm and rainy period, as expected for tropical and seasonal regions. However, the temporal segregation between groups of species within the rainy season seems to facilitate the coexistence of generalist species typical of open and/or anthropogenic areas.

As comunidades de anfíbios anuros, principalmente de regiões tropicais, são influenciadas diretamente pelas condições ambientais, as quais desempenham um papel importante na estruturação e regulação das comunidades. Esse estudo teve como objetivo determinar a diversidade de modos reprodutivos, a temporada de vocalização e testar a correlação das variáveis climáticas sobre a riqueza, a abundância dos anuros adultos e dos girinos e sobre a atividade de vocalização dos machos em 12 corpos d'água localizados no interior e entorno do Parque Nacional das Emas, sudoeste do estado de Goiás, Brasil. Foram realizadas 16 amostragens entre dezembro de 2005 e março de 2008. Um total de 25 espécies de cinco famílias foram registradas: Bufonidae (uma espécie), Hylidae (nove espécies), Leptodactylidae (oito espécies), Leiuperidae (seis espécies) e Microhylidae (uma espécie). Quatro padrões de atividade reprodutiva foram reconhecidos entre as espécies: contínuo, intermediário, prolongado e explosivo. A riqueza de anuros adultos, a abundância e atividade de vocalização dos machos foram positivamente relacionadas com a temperatura do ar, umidade e precipitação. A riqueza de girinos foi positivamente relacionada com a precipitação e com a temperatura da água, mas não houve relação da abundância de girinos com nenhum dos descritores climáticos. Foram registrados seis modos reprodutivos: 56% das espécies apresentaram modos reprodutivos aquáticos generalizados (modo 1 e 4), e 44% depositam os ovos em ninhos de espuma (modos 11, 13, 30 e 32). As espécies registradas no presente estudo apresentaram predominância de modos reprodutivos generalizados e padrão reprodutivo tipicamente associado ao período quente e chuvoso, como esperado para regiões tropicais sazonais. Entretanto, a segregação temporal entre grupos de espécies dentro do período chuvoso parece facilitar a coexistência de espécies generalistas típicas de áreas abertas e/ou antrópicas.

RESUMO

The communities of anuran amphibians, especially in tropical regions, are directly influenced by environmental conditions, whfich play an important role in structuring and regulating communities. This study aimed to determine the diversity of reproductive modes, season of vocalization and to test correlation among climatic variables and richness, abundance of adult frogs and tadpoles, and activity of vocalization of males in 12 water bodies located in and around the Emas National Park, southwestern state of Goiás, Brazil. Sixteen samples were carried out between December 2005 and March 2008. A total of 25 species from five families were recorded: Bufonidae (one species), Hylidae (nine species), Leptodactylidae (eight species), Leiuperidae (six species) and Microhylidae (one species). Four patterns of reproductive activity were recognized among the species: continuous, intermediate, long and explosive. The richness of adult frogs, the abundance and activity of the calling males were positively related to air temperature, humidity and precipitation. The richness of tadpoles was positively related to precipitation and water temperature, but there was no relationship between the abundance of tadpoles with no descriptors of climate. Six reproductive modes were recorded, 56% of species had widespread aquatic reproductive modes (mode 1 and 4) and 44% deposit eggs in nests of foam (modes 11, 13, 30 and 32). The species recorded in this study showed a predominance of reproductive modes and general reproductive pattern typically associated with the warm and rainy period, as expected for tropical and seasonal regions. However, the temporal segregation between groups of species within the rainy season seems to facilitate the coexistence of generalist species typical of open and/or anthropogenic areas.

As comunidades de anfíbios anuros, principalmente de regiões tropicais, são influenciadas diretamente pelas condições ambientais, as quais desempenham um papel importante na estruturação e regulação das comunidades. Esse estudo teve como objetivo determinar a diversidade de modos reprodutivos, a temporada de vocalização e testar a correlação das variáveis climáticas sobre a riqueza, a abundância dos anuros adultos e dos girinos e sobre a atividade de vocalização dos machos em 12 corpos d'água localizados no interior e entorno do Parque Nacional das Emas, sudoeste do estado de Goiás, Brasil. Foram realizadas 16 amostragens entre dezembro de 2005 e março de 2008. Um total de 25 espécies de cinco famílias foram registradas: Bufonidae (uma espécie), Hylidae (nove espécies), Leptodactylidae (oito espécies), Leiuperidae (seis espécies) e Microhylidae (uma espécie). Quatro padrões de atividade reprodutiva foram reconhecidos entre as espécies: contínuo, intermediário, prolongado e explosivo. A riqueza de anuros adultos, a abundância e atividade de vocalização dos machos foram positivamente relacionadas com a temperatura do ar, umidade e precipitação. A riqueza de girinos foi positivamente relacionada com a precipitação e com a temperatura da água, mas não houve relação da abundância de girinos com nenhum dos descritores climáticos. Foram registrados seis modos reprodutivos: 56% das espécies apresentaram modos reprodutivos aquáticos generalizados (modo 1 e 4), e 44% depositam os ovos em ninhos de espuma (modos 11, 13, 30 e 32). As espécies registradas no presente estudo apresentaram predominância de modos reprodutivos generalizados e padrão reprodutivo tipicamente associado ao período quente e chuvoso, como esperado para regiões tropicais sazonais. Entretanto, a segregação temporal entre grupos de espécies dentro do período chuvoso parece facilitar a coexistência de espécies generalistas típicas de áreas abertas e/ou antrópicas.