Dieta e Frugivoria por Marsupiais Didelfideos em uma floresta estacional semidecidual no Parque Nacional Do Iguaçu, Paraná, Brasil

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

This study has the aim to analyse the diet of didelphid marsupials, namely the black-eared opossum Didelphis aurita, the woolly mouse opossum Micoureus paraguayanus and the western woolly opossum Caluromys lanatus, besides the effects of resource partitioning among these sympatric species, in a seasonal forest of southern Brazil. For this purpose, 100 live traps were set in the forest canopy (20 m apart; above 10 m in height) and other 50 (40 m apart) on the ground from August 2004 to July 2005. Species of opossums captured were identified and separated by sex, age and by their reproductive condition in order to compare diets among these classes. Their faeces were collected on the trap floor and analyzed after being washed with a 1 mm mesh. After 8,500 trap-nights, 41 faecal samples of D. aurita, eight of M. paraguayanus and two of C. lanatus were sampled. The three species of opossum studied were heterogeneous in relation to thein diet composition, being significantly different from each other. When compared, individuals of D. aurita trapped in the canopy vs. those trapped in the floor level, or even regarding age and sex classes, did not differ in diet composition. Nevertheless, all individuals of D. aurita trapped at the canopy were young, which corroborates an observed trend to young have a larger dietary niche not a young canopy was captured while the ones on the floor were captured as young individuals as adult individuals. All species presented insects in their diets, but with a to consume fruits (both species) or vertebrates (D. aurita). Hence, D. aurita was more omnivorous, and M. paraguayanus, regarding its little faecal samples, revealed several fruit species in their diet, such as Cecropia pachystachia and Piper sp. The role of these marsupials as opportunistic consumers as well as the role of body size and habitat differences determining trends in diet are discussed.Seasonal forests have marked periods of rains and drought, and animals living there are thought to be adapted to this condition. This study aims to obtain information about relationships between availability of food resources (fruits) and biotic parameters of didelphid marsupials, such as reproduction level and fruit consumption, in a seasonal semideciduous forest of southern Brazil. This study was developed with Micoureus paraguayanus and Didelphis aurita, focusing mainly the similarities in the rhythms of consumption rather than their main differences in foraging. For this purpose, 100 live traps were set in the forest canopy (20 m apart; above 10 m in height) and other 50 (40 m apart) on the ground from August 2004 to July 2005. Their faeces were collected on a trap floor and seeds from them were identified and counted. The fruit availability in the area was quantified monthly through the collection of flesh fruits and flowers available on the ground, at 10 transect lines of 1 m in width. Because fruits of Piper do not detach usually from stems, this shrub species was sampled by counting fruiting individuals in the same 10 transect lines. Results were analyzed based on 33 faecal samples of D. aurita and eight of M. paraguayanus. Regarding fruits, diversity indexes of Shannon observed for the environment and for the marsupials species usually matched, being higher during the rainy months (November to March). Hence, rhythms of fructification of Piper sp. correlated to their consumption by marsupials (rs = 1.00, P = 0.04, for D. aurita and rs = 0.40, P = 0.60, for M. paraguayanus). There were trends to the major proportion of independent young and lactant females of D. aurita correlate to the peaks of fruit availability in the environment, mainly in November and January. Thus, the availability of resources had an important role in the reproduction and foraging behavior of the marsupial species. Marsupials are also adapted to reproduce and release young during favourable times, which matched with the warmer and rainy season at the seasonal semideciduous forest of southern Brazil.

ASSUNTO(S)

micoureus paraguayanus didelphis aurita didelphis marsupialis caluromys lanatus ecologia gambá

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