Bali Island EcologyBali lies just to the west of the Wallace Line, and thus has a fauna that is Asian in character, with very little Australasian influence, and has more in common with Java than with Lombok. An exception is the Yellow-crested Cockatoo, a member of a primarily Australasian family.

There are around 280 species of birds, including the critically endangered Bali Starling, which is endemic. Others Include Barn Swallow, Black-naped Oriole, Black Racket-tailed Treepie, Crested Serpent-eagle, Crested Treeswift, Dollarbird, Java Sparrow, Lesser Adjutant, Long-tailed Shrike, Milky Stork, Pacific Swallow, Red-rumped Swallow, Sacred Kingfisher, Sea Eagle, Woodswallow, Savanna Nightjar, Stork-billed Kingfisher, Yellow-vented Bulbul, White Heron, Great Egret.

Until the early 20th century, Bali was home to several large mammals: the wild Banteng, leopard and the endemic Bali tiger. The Banteng still occurs in its domestic form, whereas leopards are found only in neighbouring Java, and the Bali tiger is extinct. The last definite record of a tiger on Bali dates from 1937, when one was shot, though the subspecies may have survived until the 1940s or 1950s. The relatively small size of the island, conflict with humans, poaching and habitat reduction drove the Bali tiger to extinction. This was the smallest and rarest of all tiger subspecies and was never caught on film or displayed in zoos, whereas few skins or bones remain in museums around the world. Today, the largest mammals are the Javan Rusa deer and the Wild Boar.[citation needed] A second, smaller species of deer, the Indian Muntjac, also occurs. Saltwater crocodiles were once present on the island, but became locally extinct sometime during the last century.

Squirrels are quite commonly encountered, less often is the Asian Palm Civet, which is also kept in coffee farms to produce Kopi Luwak. Bats are well represented, perhaps the most famous place to encounter them remaining the Goa Lawah (Temple of the Bats) where they are worshipped by the locals and also constitute a tourist attraction. They also occur in other cave temples, for instance at Gangga Beach.

Two species of monkey occur. The Crab-eating Macaque, known locally as "kera", is quite common around human settlements and temples, where it becomes accustomed to being fed by humans, particularly in any of the three "monkey forest" temples, such as the popular one in the Ubud area. They are also quite often kept as pets by locals.

The second monkey, endemic to Java and some surrounding islands such as Bali, is far rarer and more elusive is the Javan Langur, locally known as "lutung". They occur in few places apart from the Bali Barat National Park. They are born an orange colour, though by their first year they would have already changed to a more blackish colouration.

In Java however, there is more of a tendency for this species to retain its juvenile orange colour into adulthood, and so you can see a mixture of black and orange monkeys together as a family. Other rarer mammals include the Leopard Cat, Sunda Pangolin and Black Giant Squirrel.

Snakes include the King Cobra and Reticulated Python. The Water Monitor can grow to at least 1.5 m (4.9 ft) in length and 50 kg (110 lb) and can move quickly. The rich coral reefs around the coast, particularly around popular diving spots such as Tulamben, Amed, Menjangan or neighbouring Nusa Penida, host a wide range of marine life, for instance Hawksbill Turtle, Giant Sunfish, Giant Manta Ray, Giant Moray Eel, Bumphead Parrotfish, Hammerhead Shark, Reef Shark, barracuda, and sea snakes. Dolphins are commonly encountered on the north coast near Singaraja and Lovina.

A team of scientists conducted a survey from 29 April 2011 to 11 May 2011 at 33 sea sites around Bali. They discovered 952 species of reef fish of which 8 were new discoveries at Pemuteran, Gilimanuk, Nusa Dua, Tulamben and Candidasa, and 393 coral species, including two new ones at Padangbai and between Padangbai and Amed. The average coverage level of healthy coral was 36% (better than in Raja Ampat and Halmahera by 29% or in Fakfak and Kaimana by 25%) with the highest coverage found in Gili Selang and Gili Mimpang in Candidasa, Karangasem regency.

Many plants have been introduced by humans within the last centuries, particularly since the 20th century, making it sometimes hard to distinguish what plants are really native. Among the larger trees the most common are: Banyan trees, Jackfruit, coconuts, bamboo species, acacia trees and also endless rows of coconuts and banana species.

Numerous flowers can be seen: hibiscus, frangipani, bougainvillea, poinsettia, oleander, jasmine, water lily, lotus, roses, begonias, orchids and hydrangeas exist.

On higher grounds that receive more moisture, for instance around Kintamani, certain species of fern trees, mushrooms and even pine trees thrive well. Rice comes in many varieties. Other plants with agricultural value include: salak, mangosteen, corn, Kintamani orange, coffee and water spinach.