RESUMO

We studied communities of small mammals and their ticks in endemic (E) and non-endemic (NE) areas for Brazilian spotted fever (BSF), aiming to infer if diversity parameters of parasites and hosts could be related to occurrence and prevalence of rickettsial infection, especially Rickettsia rickettsii. We compared E and NE areas in human-modified landscapes (HMLs) and natural areas (BIO) with no report of BSF cases. Composition and equitability were important components of diversity explaining differences among areas. The marsupial Didelphis albiventris was dominant in HMLs, but not in natural areas, and this opossum was the main host for the tick Amblyomma sculptum, principal vector of R. rickettsii, especially in E areas. Communities of ticks were dominated by A. sculptum, followed by Amblyomma dubitatum in E areas. In NE areas, this dominance was inverted, with more A. dubitatum than A. sculptum infesting small mammals, but the numbers of ticks were much lower than in E areas. Composition and abundance of ticks in natural areas were very dissimilar from HMLs, with the lowest tick burdens. Didelphis albiventris in E areas presented higher seroprevalence and endpoint titres against R. rickettsii than in other areas. At least three Rickettsia species, non-pathogenic to humans, were detected in natural areas (Rickettsia bellii, Rickettsia amblyommatis and 'Candidatus Rickettsia andeanae'), and only one non-pathogenic species in HMLs (R. bellii). Our results suggest that higher diversity of ticks, hosts and rickettsiae could be relevant factors in buffering the effect in BSF occurrence. Particularly for D. albiventris, its importance has to be quantified in further studies considering the epidemiological scenario of BSF.

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RESUMO

Ecological niche is the multidimensional space comprising the resources used by an organism. Intraspecific variation in resource exploitation is common in reptile populations to maximize coexistence of individuals. The use of stable isotope analysis is an effective tool when there are variations in resource exploitation, since it can provide quantitative information about food consumption and habitat use. Mesoclemmys vanderhaegei (Bour, 1973) is a medium-sized turtle with a limited distribution in south central Brazil and Paraguay. In spite of that, little is known about its ecology. In this study we used stable isotope analysis to understand the intraspecific trophic niche variation in M. vanderhaegei at Serra das Araras Ecological Station, state of Mato Grosso, Brazil. The isotopic ratios of δ15N and δ13C were determined in claw samples collected from 14 males and 14 females. Isotopic niche width values were not statistically different between the sexes, there was a high degree of overlap between sexual niches and there were no relationships between isotopic compositions and body size. These results suggest that individuals of both sexes and throughout their ontogenetic development exploit food resources with the same isotopic baseline.(AU)

Assuntos

RESUMO

Ecological niche is the multidimensional space comprising the resources used by an organism. Intraspecific variation in resource exploitation is common in reptile populations to maximize coexistence of individuals. The use of stable isotope analysis is an effective tool when there are variations in resource exploitation, since it can provide quantitative information about food consumption and habitat use. Mesoclemmys vanderhaegei (Bour, 1973) is a medium-sized turtle with a limited distribution in south central Brazil and Paraguay. In spite of that, little is known about its ecology. In this study we used stable isotope analysis to understand the intraspecific trophic niche variation in M. vanderhaegei at Serra das Araras Ecological Station, state of Mato Grosso, Brazil. The isotopic ratios of δ15N and δ13C were determined in claw samples collected from 14 males and 14 females. Isotopic niche width values were not statistically different between the sexes, there was a high degree of overlap between sexual niches and there were no relationships between isotopic compositions and body size. These results suggest that individuals of both sexes and throughout their ontogenetic development exploit food resources with the same isotopic baseline.

Assuntos

RESUMO

The White-naped Jay Cyanocorax cyanopogon (Wied, 1821) is an omnivorous and opportunistic species, with a multifarious diet. In view of the scarcity of available data in the literature, the aim was to investigate and describe the bird's diet, location of food items, foraging tactics, actual feeding behavior and intraspecific interactions, as a means of defining the items consumed. The study was carried out in a Cerrado area in the Araguaia Campus of the Federal University of Mato Grosso – UFMT, in Pontal do Araguaia, Mato Grosso State, Brazil, from August to December, 2006, and from April to October, 2010. All the feeding events were recorded through 136 hours of animal focal sampling, whereby it was shown that these birds predominantly consume animal nutrients, replenished by vegetable items and human food-waste. Arthropods were predominant in the diet, with ants as the most abundant and frequent item. The fruits, flowers and seeds of eleven plant species were also consumed. Food-waste, representing about 1/10 of the total, was constantly consumed even when other food sources were available. Although active among the various strata, foraging is mainly on the ground. In the event of food-scarcity, the strategy employed is the hierarchical deployment of the members of various-sized groups, with the avoidance of direct competition. This versatility during all seasons, confirms total adaptation to the anthropic environment surrounded by native habitats that characterized the study site.

Cyanocorax cyanopogon (Wied, 1821) é uma espécie onívora e oportunista, que se alimenta de diferentes itens alimentares. Como há poucos relatos na literatura sobre sua alimentação, este estudo visou descrever os itens alimentares consumidos, o local de captura do alimento, as táticas de forrageamento, o comportamento alimentar e as interações intraespecíficas de C. cyanopogon. O estudo foi realizado em uma área de Cerrado do Campus Universitário do Araguaia, Universidade Federal de Mato Grosso, em Pontal do Araguaia/MT, de agosto a dezembro de 2006 e de abril a outubro de 2010. Por meio da amostragem animal focal foram registrados todos os eventos alimentares, num total de 136 h de observações. Os resultados demonstraram que C. cyanopogon consome predominantemente alimentos de origem animal, seguidos pelos de origem vegetal e por resíduos alimentares. Os artrópodes foram predominantes em sua dieta e as formigas foram os itens animais mais abundantes e frequentes. Frutos, flores e sementes de onze espécies de plantas também foram consumidos. Resíduos alimentares representaram cerca de um décimo dos itens consumidos, sendo ingeridos mesmo em períodos de disponibilidade de outras fontes alimentares. C. cyanopogon é forrageadora ativa e utiliza diferentes estratos para a captura do alimento, com maior utilização do solo. Forrageia sempre em grupos de tamanhos variados e apresenta um sistema hierárquico para o consumo de itens menos abundantes, sem haver competição direta pelo alimento. Por consumirem diferentes tipos de alimentos e em todas as estações do ano, conclui-se que C. cyanopogon está totalmente adaptada ao ambiente ocupado pelo ser humano, mas circundado por vegetação nativa, característica do local de estudo.

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RESUMO

As capivaras são roedores diurnos, vivendo próximos a cursos d’água e com complexas relações sociais. A expansão das atividades humanas tem avançado sobre áreas de uso de capivaras. A adaptação das capivaras a ambientes antropizados é um novo desafio para a ciência do comportamento e esse estudo visou avaliar o padrão comportamental de um grupo de 22 capivaras livres na cidade de Viçosa-MG. As observações dos comportamentos coletivos e individuais foram por varredura instantânea em períodos diurno e noturno durante 12 meses. Os comportamentos mais observados foram: forrageamento, repouso em terra, paradas após perturbação, deslocamento após perturbação e conflitos. Houve menor atividade durante as horas do dia em contraste com maior atividade durante o período noturno. Os resultados sugerem que capivaras podem trocar o turno das atividades em função das condições locais. O grupo estudado indicou maior atividade noturna, o que difere de outros estudos com animais sem influência antrópica.

The capybara is a diurnal rodent who lives near to streams and has a complex social hierarchy. The expansion of human activities have advanced on areas of use of capybaras. The adaptation of the capybara to anthropized environments is a new challenge to the science of behavior and this study aimed to assess the behavioral pattern of a group of 22 free-living capybaras in the city of Viçosa-MG. The observations of individual and collective behaviors were made by the method of instantaneous scanning in daytime and evening for 12 months. The most common behaviors observed were: foraging, rest on land, stop after disturbance, move after disturbance and conflict. There was less activity during the daytime hours in contrast with most activity during the night. The results suggest that capybaras may change the turn of activities based on local conditions. The studied group showed greater nocturnal activity, which differs from other studies in animals without human influence.

Assuntos

RESUMO

As capivaras são roedores diurnos, vivendo próximos a cursos dágua e com complexas relações sociais. A expansão das atividades humanas tem avançado sobre áreas de uso de capivaras. A adaptação das capivaras a ambientes antropizados é um novo desafio para a ciência do comportamento e esse estudo visou avaliar o padrão comportamental de um grupo de 22 capivaras livres na cidade de Viçosa-MG. As observações dos comportamentos coletivos e individuais foram por varredura instantânea em períodos diurno e noturno durante 12 meses. Os comportamentos mais observados foram: forrageamento, repouso em terra, paradas após perturbação, deslocamento após perturbação e conflitos. Houve menor atividade durante as horas do dia em contraste com maior atividade durante o período noturno. Os resultados sugerem que capivaras podem trocar o turno das atividades em função das condições locais. O grupo estudado indicou maior atividade noturna, o que difere de outros estudos com animais sem influência antrópica.(AU)

The capybara is a diurnal rodent who lives near to streams and has a complex social hierarchy. The expansion of human activities have advanced on areas of use of capybaras. The adaptation of the capybara to anthropized environments is a new challenge to the science of behavior and this study aimed to assess the behavioral pattern of a group of 22 free-living capybaras in the city of Viçosa-MG. The observations of individual and collective behaviors were made by the method of instantaneous scanning in daytime and evening for 12 months. The most common behaviors observed were: foraging, rest on land, stop after disturbance, move after disturbance and conflict. There was less activity during the daytime hours in contrast with most activity during the night. The results suggest that capybaras may change the turn of activities based on local conditions. The studied group showed greater nocturnal activity, which differs from other studies in animals without human influence.(AU)

Assuntos