Conservation efforts are normally directed toward large, charismatic mammals. The unfortunate underestimation of small mammals often leads to ineffective conservation programs, where many endangered species are ignored. According to the IUCN (International Union for the Conservation of Nature), small mammals are as threatened as any major group of large mammals. Indeed, three quarters of the recent mammal extinctions have been with small mammals.

These animals suffer from habitat loss, pollution, hunting and competition from invasive species. In fragmented habitats, small isolated populations face additionally from demographic and genetic decline; effects that seem to be accentuated in small mammals due to their naturally higher rates of population oscillations. They are further compromised because of their limited capacity to move between forest fragments.

It is incorrectly believed that high population densities , requirements for smaller areas and the potential for quick population growth protects small mammals from extinction. In fact, these parameters vary greatly and the animals' short generation time tends to make them extremely prone to stochastic habitat perturbations.

Since 2002, the IPÊ "Small Mammals Project" has used animal mark and release protocols to study characteristic of these species and the effects of fragmentation on their populations in an effort to design better conservation strategies.

When an animal is captured, it is marked with a numbered ear-tag and several data are recorded, including: location of capture, type and position of trap, sex and weight, as well as other biometric information. Tissue samples are taken for eventual genetic analyses, faeces for diet studies and ectoparasites are collected for epidemiological work.

The objectives of the "Small Mammals Project" are as follows:

• To research the history of forest fragmentation in the Pontal do Paranapanema and identify areas undergoing regeneration;

• To survey populations of rodents and marsupials in the Morro do Diabo State Park and surrounding forests;

• To identify the effects of landscape structure on the population parameters of these species;

• To identify species of small mammals that are most sensitive to fragmentation and evaluate their potential as habitat indicators;

• To conduct a genetic analysis of these populations.