Os gambás são animais generalistas em termos ecológicos, tendo, em geral, abundância aumentada em fragmentados florestais. Sendo assim, eles são importantes indicadores para o entendimento da dinâmica desses fragmentos. Foi estudada, ao longo de 1 ano, uma população de gambás (Didelphis albiventris) em um fragmento de floresta estacional semidecidual de 7 ha e seu entorno agrícola. Estimaram-se, mensalmente, a abundância populacional, a composição etária e a proporção sexual. Foi possível constatar dois movimentos dos indivíduos entre as áreas estudadas (fragmento e entorno). A flutuação populacional apresentou um padrão anual com um pico populacional na estação seca.

The white-eared-opossums are habitat generalist animals and occur in high abundance in forest fragments. Therefore these animals are important to understand the dynamics of this landscape. The population of Didelphis albiventris in a 7 ha stational semidecidual forest fragment and its agricultural surroundings was studied during one year. The population abundance, age structure and sex ratio were estimated monthly. Two movements between the fragment and the surrounding area were detected. The population dynamics showed an annual pattern with a high peak during the dry season.

The aim of this work was to analyze 17 β estradiol and estrone, natural estrogenic hormones present in domestic effluents and animal excreta, in the public water supply system of Jaboticabal, SP. The results have shown the presence of estrogens in 22% of the samples in concentrations from 6,8 ng L-1 (treated water) to 30,6 ng L-1 (riverhead) for 17 β estradiol and 600 ng L-1 of estrone (stream), respectively. We concluded that animal wastes, discharges from the wastewater treatment station, and discharges of domestic effluent without treatment from rural proprieties were probably the cause of this contamination.