The wildlife of Singapore is surprisingly diverse despite its rapid urbanisation. The majority of fauna that still remains on the island exists in various nature reserves such as the Bukit Timah Nature Reserve and the Sungei Buloh Wetland Reserve.^[1]

In 1819, Singapore was mostly covered in rainforests. During that time, it still contained flora shared with the Malay Peninsula, but even then, the biodiversity of fauna was relatively low. Following the establishment of the British trading post, rapid deforestation began due to crop cultivation, and was largely completed by the 20th century. By some estimates, there has been a loss of 95% of the natural habitats of Singapore over the course of the past 183 years.^[2] Due to the deforestation, over twenty species of freshwater fish, 100 species of bird, and a number of mammals became locally extinct.^[3] A 2003 estimate puts the amount of extinct species as over 28%.^[4]

In modern times, over half of the naturally occurring fauna and flora in Singapore is present only in nature reserves, which comprise only 0.25% of Singapore's land area.^[2] Estimates made in 2003 have said that the rapid habitat destruction will culminate in a loss of 13-42% of populations in all of Southeast Asia. ^[5] To combat these problems, the Singaporean government has made the Singapore Green Plan in 1992 and the new Singapore Green Plan in 2012 to continue it. The plan aims to keep tabs on the unstable populations of fauna and flora, to place new nature parks, and to connect existing parks. In addition, there were plans to set up a "National Biodiversity Reference Centre" (now known as the National Biodiversity Centre).^[6] The last goal was reached in 2006 when the centre was founded (it also accomplished the establishment of two new nature reserves in 2002^[7]). Since its foundation it has been formulating various specific initiatives including attempts to conserve the hornbill and the rare dragonfly Indothemis limbata.^[8]

Singapore currently contains 1358 known species of native vascular plants, of which approximately 759 are critically endangered.^[16]

Singapore's land area is dominated by urban development that is interspaced by natural reserves, waterways, parks and a large interlinked network of over 300km of park connectors (PCN).^[17] The indigenous wildlife that has adapted to the urban environment includes the following fauna:

1. Smooth coated otter (Lutrogale perspicllata) - in 2022, the local otter population has expanded to 17 families "fishing for tilapia in waterways and sleeping under bridges". There were reports of people who had their prized koi collection decimated by hungry otters.^[18]

2. Long tailed macaques (Macaca fascicularis) numbered more than 2,000 according to a 2015 census. There were reports of macaques scaling HDB buildings and invading homes.^[19]

3.The Oriental Pied Hornbill (Anthracoceros albirostris) is native to Singapore and the species had declined to the point of local extinction during the 19^th century.^[20] However, these birds made a comeback, they were known to have established a thriving population on Pulau Ubin and on occasion, could be sighted at various locations throughout Singapore.^[21]

4. Wild boars (sus scrofa) are native to Singapore with some weighing up to 100kg and could be sighted in urban areas close to the forested areas. There were reports of wild boar attacking people who strayed into their territory.^[22]

Other wildlife sightings include the following:

1. Critically endangered Sunda pangolin (Manis Javanica)^[23][24][25]

2. Sambar deer (Rusa unicolor) which re-colonised the Central Catchment Reserve after escaping from the Zoo in the 1970s.^[26] In 2023, there was a report of road kill along the Bukit Timah expressway.^[27]

• Environmental issues in Singapore