As the population grows, the park's grasslands are no longer providing enough food. Female deer are believed to be leaving the park with their young, while male deer, which naturally tend to move away from groups, may encounter them outside the park. Experts believe some deer have established new territories and reproduced beyond the park, creating second- and third-generation populations that have never lived within its grounds. Reports suggest deer living outside the park can be more aggressive than those accustomed to visitors inside it. Nara's deer are designated as a national natural monument, including wild animals outside Nara Park. Prefectural officials and members of deer protection organizations generally respond to reports by approaching herds from behind and driving them back toward the park.