Guilherme Mourão

Distribuição e quantificação de classes de vegetação do Pantanal através de levantamento aéreo

An aerial survey was adapted and used for the first time to elaborate maps of distribution and quantification of vegetation classes in the Pantanal wetland, per sub-region. Sixteen vegetation classes where identified based on phytophysiognomic aspects, the most important being grassland (31.1%), cerradao woodland (22.1%), cerrado (14.3%), marshes (7.4 %), semideciduous forest (4.0%), gallery forest (2.4%) and floating mats (2.4%). These informations can support decisions in the conservation or selection of preserved areas, as well as to help to monitor vegetation over a vast and remote region.

Aerial surveys of caiman, marsh deer and pampas deer in the Pantanal Wetland of Brazil

The yacare caiman (Caiman c. yacare) was illegally hunted in the Pantanal during the 1970s and 1980s at levels that may have reached one million skins per year. The possibility that yacare caiman had been over-exploited generated pressure for a monitoring programme for caiman populations. The marsh deer (Blastocerus dichotomus) and pampas deer (Ozotocerus bezoarticus) are listed as endangered in Brazil and need the protection of effective management programmes. Ground surveys are difficult for the extensive and inaccessible Pantanal Wetland, south-western Brazil, but aerial surveys provided information that allowed re-evaluation of conservation priorities. Caiman and marsh deer have larger populations than was believed. Preliminary data indicates that the pampas deer density decreased at a rate of about 30% per year from 1991 to 1993. This indicates the need for detailed ground-level studies for the pampas deer population in the Pantanal. We recommend a long term monitoring program using standardized counting procedures for wildlife populations in the Pantanal.

Trypanosoma cruzi Infection in Neotropical Wild Carnivores (Mammalia: Carnivora): At the Top of the T. cruzi Transmission Chain

Little is known on the role played by Neotropical wild carnivores in the Trypanosoma cruzi transmission cycles. We investigated T. cruzi infection in wild carnivores from three sites in Brazil through parasitological and serological tests. The seven carnivore species examined were infected by T. cruzi, but high parasitemias detectable by hemoculture were found only in two Procyonidae species. Genotyping by Mini-exon gene, PCR-RFLP (1f8/Akw21I) and kDNA genomic targets revealed that the raccoon (Procyon cancrivorus) harbored TcI and the coatis (Nasua nasua) harbored TcI, TcII, TcIII-IV and Trypanosoma rangeli, in single and mixed infections, besides four T. cruzi isolates that displayed odd band patterns in the Mini-exon assay. These findings corroborate the coati can be a bioaccumulator of T. cruzi Discrete Typing Units (DTU) and may act as a transmission hub, a connection point joining sylvatic transmission cycles within terrestrial and arboreal mammals and vectors. Also, the odd band patterns observed in coatis’ isolates reinforce that T. cruzi diversity might be much higher than currently acknowledged. Additionally, we assembled our data with T. cruzi infection on Neotropical carnivores’ literature records to provide a comprehensive analysis of the infection patterns among distinct carnivore species, especially considering their ecological traits and phylogeny. Altogether, fifteen Neotropical carnivore species were found naturally infected by T. cruzi. Species diet was associated with T. cruzi infection rates, supporting the hypothesis that predator-prey links are important mechanisms for T. cruzi maintenance and dispersion in the wild. Distinct T. cruzi infection patterns across carnivore species and study sites were notable. Musteloidea species consistently exhibit high parasitemias in different studies which indicate their high infectivity potential. Mesocarnivores that feed on both invertebrates and mammals, including the coati, a host that can be bioaccumulator of T. cruzi DTU’s, seem to take place at the top of the T. cruzi transmission chain.

Home range of giant anteaters (Myrmecophaga tridactyla) in the Pantanal wetland, Brazil

To obtain data on home range, movements, activity and habitat use by giant anteaters Myrmecophaga tridactyla , seven animals were captured, radio-collared and monitored from March to December 2001 in a 104-km 2 study area in the Pantanal wetland, Brazil. Four of five males used areas that covered 4.0–7.5 km 2 (5.7±1.7 km 2 ), and one of two females monitored occupied a larger area (11.9 km 2 ) than the males, but none of the curves of cumulative area unequivocally reached the asymptote. Generally, there was considerable overlap among individual areas used. The home-range estimates were calculated using the 100% minimum convex polygon, and 95% adaptive kernel methods. The areas used by the giant anteaters in the Pantanal wetland were larger than home ranges of giant anteaters in the Serra da Canastra National Park, Brazil. The habitat types were generally used in the same order as they occurred in each home range. Two giant anteaters previously monitored with VHF radio-telemetry were subsequently tracked with a modified global positioning (GPS) system in different periods. The modified GPS acquired data on activity and habitat use for c . 9 days. Giant anteaters did not show a similar pattern of habitat use during the period of study using the modified GPS unit, but their activity patterns were similar. One of the ranges recorded over 9 days with this method was larger than the range obtained over 252 days by standard VHF radio-telemetry.

Intraspecific, interspecific, and seasonal differences in the diet of three mid-sized carnivores in a large neotropical wetland

The diet and partitioning of food resources among mid-sized mammalian carnivores is poorly known, especially in the tropics. We evaluated the resource partitioning between Leopardus pardalis (ocelot), Cerdocyon thous (crab-eating fox), and Nasua nasua (brown-nosed coati) in the Pantanal of Brazil. Between December 2005 and February 2008, we collected data necessary to better understand interspecific, intraspecific, and seasonal variability in diet. Food habits were assessed by analysis of feces (n = 293) collected from known individuals (n = 128), and differences in dietary composition were evaluated through nonmetric dimensional scaling using the Jaccard similarity index. The main diet differences were observed between the specialist ocelot and the more generalist crab-eating fox and brown-nosed coati. Crab-eating foxes and brown-nosed coatis preyed on arthropods, fruits, and vertebrates whereas ocelots preyed almost entirely on vertebrates, mainly rodents and snakes. Ocelots’ consumption of snakes was the highest ever recorded, as was the extent of carnivory by brown-nosed coatis. For the crab-eating fox and the brown-nosed coati, there were large differences between the use of fruits and animal foods in the wet and dry season. Yet for both species there were no significant differences in the diets of males and females. Despite the conspicuous sexual dimorphism and spatial segregation that are typical of brown-nosed coatis, the results do not support the hypothesis that size dimorphism is primarily an adaptation to reduce intersexual competition for food. Rather, dimorphisms and patterns of space use may be more related to competition among males for access to females.

Survey of broad-snouted caiman Caiman latirostris, marsh deer Blastocerus dichotomus and capybara Hydrochaeris hydrochaeris in the area to be inundated by Porto Primavera Dam, Brazil

We surveyed broad-snouted caiman Caiman latirostris, marsh deer Blastocerus dichotomus and capybara Hydrochaeris hydrochaeris along the Parana River of southeastern Brazil in the area to be flooded by the Porto Primavera Dam. We conducted night-light counts along 124 km of the Parana River and its tributaries. The mean observed density was 0·12 caiman per km surveyed. We counted caiman nests, marsh deer, and capybara groups over 957 km2 of habitat representing 43% of the area to be flooded, by means of aerial survey. The mean estimated density was 0·49 caiman nest/km2, 0·51 deer/km2, and 0·16 capybara groups/km2. Extending these results to the 1280 km2 of floodplains in the area, we estimated 630 caiman nests per year, 650 marsh deer, and 200 groups of capybara to occur in the area. We recommend the creation of a protected area to guarantee the survival of the broad-snouted caiman and marsh deer in this region.

Marsh Deer (Blastocerus dichotomus) Distribution as a Function of Floods in the Pantanal Wetland, Brazil

The marsh deer (Blastocerus dichotomus, Cervidae) inhabits floodplains and marshlands of South America and is threatened with extinction. We conducted two aerial surveys in the central southern region of the Pantanal to evaluate population distribution at the end of the dry season and the peak of the flooding season. Our results show an aggregated distribution during the dry season and a relatively diffused distribution in the flooding season. Population density estimates are 0.382 ± 0.362 deer/km2 in the dry season, and 0.395 ± 0.144 deer/km2 in the flooding season. Population size remained essentially unchanged between the seasons. In the study area, the marsh deer moved up to 20 km between the dry and flooding seasons. The design of protected areas should consider migration distances to offer enough area to protect marsh deer populations throughout the year.

Estimating age of carnivores from the Pantanal region of Brazil

Abstract Conservation and management of animal populations often require knowledge about the age structure, but this information is usually difficult to discern. We propose a method to estimate the age of carnivores based on dental condition and body size measurements, and we apply the method to populations of brown-nosed coatis Nasua nasua and crab-eating foxes Cerdocyon thous in the Brazilian Pantanal. We sexed, weighed and measured 31 coatis and 45 foxes of known-age, and characterized and quantified their pattern of dental eruption and wear for the construction of a teeth condition index. Scores of the first factors of a principal component analysis including data on six body size measurements and the teeth condition index of the individuals were then used in a discriminant analysis to generate functions that can be used for estimating age of animals of unknown age. Models were validated using subsets of individuals of known age through a 3-fold cross validation process. The first functions accounted for over 90% of the discriminatory power for both species. Whereas in coatis, the first function was mainly explained by the body size measurements, in crab-eating foxes it was represented mainly by the teeth condition index. During model validation, individuals were on average classified with 88 and 80% average confidence for coatis and foxes, respectively. Our method is as accurate as other methods that are commonly applied to assess age, but less subjective. While it requires animal capturing, it is less invasive than methods requiring tissue removal such as analyses of teeth cementum annuli. The method we outlined can be used for age estimation of other populations, as long as the models are validated with a subset of animals from the region studied. It could also be useful as a model for estimating age of other carnivore species.

Space use by giant otter groups in the Brazilian Pantanal

Abstract Giant otters (Pteronura brasiliensis) live in groups that seem to abandon their territories during the flooding season. We studied the spatial ecology of giant otter groups during dry and wet seasons in the Vermelho and Miranda rivers in the Brazilian Pantanal. We monitored visually or by radiotelemetry 10 giant otter groups monthly from June 2009 to June 2011.We estimated home-range size for all groups with the following methods: linear river length, considering the extreme locations of each group, and fixed kernel. For the radiotracked groups, we also used the k-LoCoh method. Spatial fidelity and habitat selection of giant otter groups were analyzed seasonally. On the basis of k-LoCoh (98%) method, home-range sizes during the wet season (3.6–7.9 km2) were 4 to 59 times larger than during the dry season (0.1–2.3 km2). Home-range fidelity between seasons varied among giant otter groups from 0% to 87%, and 2 radiotagged groups shifted to flooded areas during the wet seasons. Giant otter groups were selective in relation to the composition of the landscape available during the dry seasons, when the river was used more intensively than other landscape features. However, they seemed to be less selective in positioning activity ranges during the wet season. During this season, giant otters were frequently observed fishing in the areas adjacent to the river, such as flooded forest, grassland, and swamps. Resumo Ariranhas (Pteronura brasiliensis) vivem em grupos, que parecem abandonar seus territórios durante a estação de inundação. Nós estudamos a ecologia espacial de grupos de ariranhas durante as estações seca e chuvosa nos rios Vermelho e Miranda no Pantanal brasileiro. Nós monitoramos visualmente ou por rádio telemetria 10 grupos de ariranhas mensalmente entre junho de 2009 e junho de 2011. Nós estimamos o tamanho da área de vida de todos os grupos através dos seguintes métodos: 1) comprimento linear do rio, considerando as localizações extremas de cada grupo, e 2) kernel fixo. Para os grupos monitorados com telemetria nós também usamos o método 3) k-LoCoh. Fidelidade espacial e seleção de habitat dos grupos de ariranhas foi analisada sazonalmente. Baseado no método de k-LoCoh (98%), os tamanhos das áreas de vidas durante a estação chuvosa (3.6 −7.9 km2) foram 4 a 59 vezes maiores do que durante as estações secas (0.1–2.3 km2). Fidelidade de área de vida entre estações variou de 0% to 87% entre os grupos de ariranhas e dois grupos monitorados com rádio telemetria dispersaram para áreas inundadas durante as estações chuvosas. Grupos de ariranhas foram seletivos em relação à composição da paisagem durante as estações secas, quando o rio foi mais intensamente utilizado em relação a outras características da paisagem. No entanto, eles pareceram ser menos seletivos no posicionamento de suas atividades durante as estações chuvosas. Durante essa estação, ariranhas foram freqüentemente observadas pescando em áreas adjacentes ao rio, como florestas inundadas, campos e brejos.

Giant otters feeding on caiman: evidence for an expanded trophic niche of recovering populations

As water along dirt roads in the Pantanal floodplains diminishes, aquatic fauna becomes restricted to shallow pools. At the end of the 2009 dry season, we filmed giant otters living in pools predating on yacare caimans. Such predation has not been recorded in giant otters inhabiting the Pantanal. Individual otters captured sub-adult caimans. The otters did not share the prey, but conspecifics stole it after conflicts. Caiman predation could be related to resource scarcity in these marginal environments. Information on diet and interactions of endangered populations may underestimate their trophic niche when they recover from over-hunting and expand into sub-optimal habitat. À medida que as águas ao longo das estradas de terra na planície pantaneira diminuem, a fauna aquática se torna restrita às poças rasas do entorno. No final da estação seca de 2009, nós filmamos ariranhas predando jacarés em baías temporárias. Este tipo de predação não foi descrito antes para ariranhas do Pantanal. As ariranhas capturaram jacarés sub-adultos, individualmente. A presa não foi dividida voluntariamente, mas foi roubada por outros indivíduos do grupo, após conflitos. Esta predação pode estar relacionada com a escassez de alimento nestes ambientes marginais. Informações de dieta e interações em populações ameaçadas talvez subestimem seu nicho trófico quando estas se recuperam, após período sem caça, e expandem para ambientes sub-ótimos.