When a forest, such as a Permanent Preservation Area, is not very well protected, it is very easy for cattle and other domestic animals to enter. This leads to the destruction of the understory, which are the plants that live from the forest floor all the way to below the forest canopy. This problem causes a kind of damage that is invisible from the sky or from satellites. When this happens, populations of Tinamidae, such as the tinamou, disappear. Species become silently and quickly regionally extinct. Understory insectivorous passerines, which often only live in quite small areas, can run a serious risk of extinction. This group of passerines are the most threatened group of birds in the Atlantic Rainforest.