In Singapore, otters live within a heavily urbanised environment. Singapore historically had populations of at least Asian small-clawed otters and smooth-coated otters but all otter species became locally extinct in the 20th century. A repopulation of the island state by smooth-coated otters began in 1998, and accelerated in 2013. The growing otter population was seen as a success story for the greening of the city. Otters have become popular with the public, and have been adopted as national symbols. This disappearance of otters in the 20th century was due to a combination of habitat destruction and pollution. The vast majority of Singapore's natural forest had been cleared, and many waterways were too polluted to support wildlife. Government efforts to improve the city's environment began in the late 1960s, and eventually saw many rivers cleaned and returned to a more natural state. Otters crossed the Straits of Johor from the Malay Peninsula to Singapore sporadically, but in 1998 a couple established itself permanently in the northwest. Others followed, settling in various locations on the northern coast. In 2013, otters were recorded migrating south, and they soon spread throughout most of the major waterways of the island. Singapore's otters have become adapted to the urban landscape of the city. Unlike smooth-coated otter populations elsewhere, they are often tolerant of human presence. Otter families often nest in artificial environments, use stairs and ladders to enter and exit waterways, and use human infrastructure to travel both on land and in water. They are opportunistic feeders, eating food that is most common in their territories, and face few natural predators. Otter families are sometimes larger than those recorded elsewhere, and pups are recorded staying with their family longer than they do elsewhere. Multiple families have been observed with more than one simultaneously lactating female. The smooth-coated otters have been found to be hybrids with Asian small-clawed otters, although the origin of this is unknown. Some Asian small-clawed otters may also have returned, although they are restricted to mangroves and smaller islands. Both otter species are protected by Singaporean law. Volunteer groups observe the otters, and the extensive popularity and recording of the otters has enabled the use of citizen science to conduct research. Human–otter conflict is rare, and otters are generally viewed positively by the public. An Otter Working Group (OWG) brings together the government, academics, and civil society organisations to conduct research and promote better human–otter relations. The success of Singapore's otters is viewed as a potential model for the success of urban otters elsewhere.
Geographic background
Singapore consists of one main 728-square-kilometre (281 sq mi) island and 62 surrounding islands of various sizes. The Straits of Johor separate these islands from the mainland Malay Peninsula, and ranges in width from around 500 metres (1,600 ft) to 1,000 metres (3,300 ft). The strait is effectively divided into two by the Johor–Singapore Causeway. Only about 5% of Singapore's original natural environment remains, although about 56% of the country is covered in some form of greenery, including parks. Many of these managed green spaces occur alongside waterways. The island has three main drainage basins: western, central (including the Downtown Core), and eastern (encompassing the northern and eastern coasts). Singapore has no natural lakes or large rivers, although artificial reservoirs have been created. Most large rivers are sealed at their mouths.
History
Historic presence and disappearance Historically, the Asian small-clawed otter was likely the most common species on Singapore. The smooth-coated otter was found in the region, but records from Singapore are limited. It may have mostly been a visitor to the island. Records of the hairy-nosed otter are difficult to confirm due to potential confusion with the smooth-coated otter. While there are Eurasian otters in other parts of Eurasia and to the south in Sumatra, there are no confirmed historical records for its presence in Singapore or the wider Malay Peninsula. Otters are highly vulnerable to habitat destruction stemming from urbanisation. Pollution affects both otters and their prey. Furthermore, the modification of rivers can often create riverbanks unsuitable for otters, as they need to spend time on land. Large-scale deforestation of the island likely began only after the founding of modern Singapore in the early 19th century. An increase in agricultural production saw lowland and mangrove forests cleared for cash crops and aquaculture. By 1900, around 90% of the original forests were lost. Increasing pollution further damaged river ecosystems, and by the 1850s, some rivers were too polluted to support aquatic life. The island's otter population disappeared sometime before the 1960s. At this time, the island's mangroves were estimated to have been reduced to 1% of their former range. By 1990, all otter species were considered locally extinct. Some small-clawed otters were kept in Singapore Zoo.
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