Lions are the only big cats that form prides, or groups, to hunt and defend their territory. Lions typically prey on baboons, water buffalo, rodents, zebras, and antelopes. As human populations increase and encroach on lion habitats, conflicts between humans and lions arise because they are forced to compete for food and space. In certain areas, lions regularly hunt and kill livestock. Livestock owners often retaliate by killing the lion or members of its pride. Researchers are trying to learn about lion behavior by using radio collars to track lions and monitor their locations and the health of the populations. In order to attach the radio collars, the lions need to be tranquilized. When the lions are sedated, scientists are able to perform a physical examination. The physicals provide information about the growth rates, ages, and general health of the lions. This information can then be used to better understand and manage lion populations, especially those that come into contact with humans and livestock.