At the same time, regions are experiencing declines in prey populations like deer and game birds. The natural instinct is to blame prey declines on the recent increases in predators. In some instances predators may be responsible for the decline, and in other cases it may be environmental change (for example, drought). In some regions, prey species have been overabundant due to the lack of predators and as predators make a comeback, the prey is put in check. To investigate whether predators are impacting prey populations, researchers are conducting research involving predator exclusion or removal. All are trying to answer the question: does predator control benefit game populations, or is it a waste of time and money?