Animals that migrate long distances often do so in search of food, water, or suitable breeding grounds. In flat terrain, these resources may be more spread out, which means that animals may need to travel farther to find them. In contrast, mountainous regions often have more concentrated resources, such as rivers, lakes, and fertile valleys, which can support larger populations of animals. This means that animals living in mountainous regions may not need to travel as far to find the resources they need. Additionally, mountainous regions often have more diverse habitats, which can provide a wider range of resources for animals. Overall, the availability and distribution of resources can play a major role in determining the distances that animals need to migrate, and this can vary depending on the terrain and habitat of the region.