Many species of bats are declining world-wide, mainly as a result of human activity. Habitat loss is a factor everywhere, and especially critical in the tropical rainforests. Diseases, such as the White-nose Syndrome in North America, and wind turbines, which are taking a huge toll on bats globally, are other challenges. These flying mammals are very useful, being critical for pollination and insect pest control and their guano is a rich natural fertilizer. As with everything in the natural world, bats are a necessary part of a healthy ecosystem.