Tamanho corporal e aspectos reprodutivos das populações de pequenos mamíferos não voadores na Floresta Nacional de Carajás-PA.

Abstract

The National Forest of Carajás, southeastern Pará, Brazil, consists of a conservation unit, which presents two striking, well the physiognomies dense Ombrophilous forest and Savana Metalófila landscapes (Canga), highlights, by predominance, great richness and diversity of species, the other by its uniqueness, recognised endemism and economic potential, arising out of its mining activities. The objectives of this study were to study the population variation and reproductive information such as sex ratio, age structure, reproductive period, in addition to studying the occurrence of sexual dimorphism, as well as the effect of two physiognomies (Canga and forest) on the body size of non-volant small mammals. The present study was carried out during the years 2010 and 2011, including during this period five climatic stations in both physiognomies. Were sampled six parallel lines, in each area, and installed 60 traps, for six consecutivo nights. And pitfall traps, with 15 buckets on each track, just in the areas of forest. For every individual captured, taxonomic Identification was made, were noted sex, reproductive condition and age as specific description for each group, including the body measurements of each individual. 1230 specimens were distributed in 22 species. As for the sex ratio, most species of marsupials and rodents did not suffer significant deviation of the ratio 1: 1 in the course of the seasons and in different physiognomies. One of the marsupials studied, only M. murina in it to cover up and in rainy seasons showed deviation in sex ratio for females, and M. pinheiroi showed deviation in sex ratio in favor of males in the forest and in the wet season. Among rodents, only the species N. lasiurus differed in sex ratio, in favour of males in the dry season. About the distribution of the age brackets in the yoke, the marsupials have a seasonal pattern, often reflecting the reproductive period with young and subadults in rainy seasons. For rodents N. lasiurus and O. amazonicus, young individuais were observed in ali seasons. In the forest the marsupials did not present differences of age brackets between stations. For ali rodents, there was an increased recruitment of juveniles in rainy seasons, in some cases as E. emmonsae and P. roberti, the amount of young people was greater than that of adults. The reproductive signs observed in the cover up by the marsupials were seasonal. O. amazonicus and rodents to N. lasiurus, reproductive signs were observed more frequently in dry times. In it, some forest species, such as M. murina, M. demerarae and M., sp. D, showed no seasonality in the reproductive signs, lactating females in both seasons. Rodents A aff. cursor and P. roberti also showed a seasonal pattern of reproduction. In the study of body size, were studied only adult individuais of the most abundant species of marsupials (M. glirina, M. murina, M. sp. D, M. pinheiroi and M. demerarae) and rodents (O. amazonicus, N. lasiurus, A aff. cursor, Neacomys sp. n., P. roberti, E. emmonsae and specimens of the genus Oecomys). For marsupials, the sexual dimorphism was evident for most species in different physiognomies, with body measurements of larger males compared to females. In rodents, the sexual dimorphism was not so obvious, showing similarity between the sexes. With the exception of N. sp. nova, which had significantly larger females compared to males. The effect of it was seen mainly in males, and males were bigger forest in relation to males captured in the yoke. The results of this study showed the importance of these two physiognomies to the ecology, diversity and maintenance of the group. And may contribute to more accurate studies about the same, such as habitat and adaptation, which are important to decision making for the proper management of natural areas.