2.1. Existing Mitigation Options

Over time, a variety of measures have been proposed and implemented, either individually or in combination, to minimize the impacts of roads on wildlife. Their main purposes are to restore some degree of connectivity, thereby reducing the barrier effect, and to prevent wildlife–vehicle collisions at particularly susceptible locations. Most measures, however, still lack studies evaluating their effectiveness, especially when considering the different responses of species or communities with distinct geographic distributions and ecological structures. Monitoring undertaken as part of the environmental licensing process can therefore provide valuable data for evaluating the different alternatives under Brazilian conditions.

Several classification systems have been proposed to group mitigation measures according to these objectives. One of the most widely adopted is that proposed byIUELL (2003), which groups measures according to whether the emphasis is on restoring connectivity or reducing wildlife–vehicle collisions. The first group includes wildlife crossing structures, either underpasses or overpasses, whereas the second includes fencing and measures related to wildlife management and driver behavior. Because a single measure often serves both purposes to varying degrees, this classification system has a considerable degree of artificiality and subjectivity. This Guide therefore classifies mitigation measures according to how they are implemented: structural interventions or management actions. Management actions are further subdivided into measures directed at driver/traffic behavior and measures directed at wildlife behavior.

Regardless of the classification method, it is important to understand the available options so that the most appropriate measure can be selected for each situation. Table 4 summarizes known mitigation measures and evaluates their effectiveness in minimizing impacts on the major wildlife groups. The characteristics of each measure are presented in greater detail in the following sections.

Translation note: This English version was preliminarily translated using ChatGPT and has not yet undergone human review.