Known for its conservation efforts, the San Diego Zoo maintains several endangered species exhibits and works with conservation groups worldwide to encourage protection of threatened wildlife. The enormous reserve has rambling scenic walkways and narrated bus tours. ‘Monkey Trails’ at the heart of the zoo includes Asian and African forests with more than 30 species of exotic birds, mammals, reptiles, and amphibians. At ‘Tiger River’, misty trails wind amid waterfalls in a tropical forest of more than 5,000 types of exotic plants and tigers, Burmese pythons and Malaysian tapirs. The most popular exhibit is the Pacific Bell Giant Panda Research Station, where several endangered pandas have given birth. The baby pandas are a big hit and long lines often form at the enclosure. The zoo hosts several "after dark "events, including live music performances and up-close animal encounters.