A satellite image of northwestern Singapore reveals comparatively more green than the rest of the island, the density and scale of green only matched by the reservoirs found in Singapore’s more central regions. This northwestern area, comprising Kranji, Lim Chu Kang, and the Sungei Buloh Wetland Reserve, is one of the homes of the non-native Günther’s frog (Sylvirana guentheri),¹ a slippery and elusive immigrant. Tracing the environmental history of this region reveals insights about the introduction and establishment of these understudied frogs in Singapore, and in this story are layered stories about land use, habitat change, and Singapore’s modernization.

The Günther’s frog is a medium to large brown frog, typically about 7-10 cm in length, with prominent dorsolateral folds on both of its sides. It feeds on smaller frogs and insects, and is known to be able to secrete a toxic fluid that can kill other species ² and chemically defend the organism from microbial infection.³ The fluid is rather special: chemical biologists are interested in the peptides that make up the species’ skin secretions for their antimicrobial properties and their potential pharmacological applications. The authors of one early study on the skin secretions of the Günther’s frog attribute the strength and significance of their peptides to a fact of evolutionary biology: “Amphibians being the first group of organisms forming a connecting link between land and water are forced to adapt and survive in a variety of conditions laden with pathogenic microbes.”⁴ Some of the first to cross onto land from sea in evolutionary history, the species developed systems of defense to explore new frontiers and new habitats.

With regards to their taxonomic history, the species was first described in 1882 in Xiamen, southeastern China, although the species is distributed throughout the subtropical regions of East and Southeast Asia, including Hong Kong, Taiwan, southern China, and Vietnam. The species is known to prefer swampy habitats, but has also been found to adapt well to cleared lands, such as agricultural fields.⁵ In Singapore, the species is one of the few non-native anuran species⁶ that has adapted itself to disturbed, decorated, and regrown habitats around the island.⁷ It is described as “widespread but uncommon” by a review of non-indigenous frogs of Singapore,⁸ although a majority of the species’ accounts in Singapore are from either the northwest (Kranji, Lim Chu Kang, Sungei Buloh) or the southwest (primarily, the Jurong Bird Park).⁹ It is unknown whether the two groups are related, or were introduced to Singapore through completely different pathways. Some postulate that the Sungei Lanchar canal may serve as a connecting bridge for the movement of the species in Singapore, but this cannot yet be confirmed without further studies.¹⁰

This points to the elusive nature of the species’ presence in Singapore. Accounts of the species are sparse to begin with: the first sighting of the species only occurred in 2008, although various accounts note hearing the frogs’ distinctive croaking as early as 1997, at the Jurong Bird Park.¹¹ In other words, the presence of the species was confirmed visually over ten years after it was first heard—this time in an “artificial pond at the entrance of the Southeast Asian Aviary” at the Sungei Buloh Nature Reserve.¹²

How was the frog introduced to Singapore, and why is it found in these locations? A compelling hypothesis regarding the frog’s introduction pathway sheds some light: it is thought that the species were introduced through ornamental plants, these plants making up a significant part of the ecologies of both the Jurong Bird Park and Sungei Buloh (and the northwestern region of Singapore, in general). An ecological characteristic of both northwestern and southwestern Singapore are their “human-made natures”—hybrid ecologies composed of imported ornamental plants and conserved local flora. In fact, in Cultural Heritage and Peripheral Spaces in Singapore, urban historian T.W. Lim argues that the ecologies of northern Singapore are meticulously constructed to appear natural: “[...] the sensitive recreation of a wild environment based on local ecology reflects Lefebvre’s concept of a tokonoma (a created man-made alcove with stylised flower arrangement but carried out to reflect nature as closely as possible).”¹³ This seems significant given international accounts of the Günther’s frog detailing its ability to flourish in man-made environments,¹⁴ and more recent accounts of the Günther’s frog in Yishun¹⁵ and the Singapore Botanic Gardens¹⁶ all seem to support this hypothesis. This is further supported by the story of the species’ introduction to Guam, where its introduction pathway is understood to have been through the importation of fish food and ornamental aquatic plants.¹⁷ The importation of ornamental plants provided a pathway for the frog to be introduced to Singapore, and the human-engineered environments in which these ornamental plants are cultivated in turn have provided a habitat for the frogs to thrive.

Thus, the environmental changes that have affected northwestern Singapore over the years are important in understanding not only how the Günther’s frog arrived in Singapore, but further what the presence of the Günther’s frog means in terms of how land is treated, and the symptoms and effects of this treatment. To explore this question, let us consider the history of northwestern Singapore and the major shifts in land use and development that have occurred over the past century.

The regions of Kranji, Lim Chu Kang, and Sungei Buloh remember a long history of radical changes. In 1890, this region was set aside as a forest reserve and purposefully isolated from development.¹⁸ However, with the construction of the Singapore-Kranji Railway in 1903, Kranji became a transport hub and economic activity gradually increased until 1938, when the region lost its reserve status.¹⁹ The following decades saw an increase in timber and construction industries,²⁰ and by the mid-1970s the ecology of the region was largely degraded as it became both an industrial hub and an advantageous location for the expansion of agricultural and aquacultural farms, namely the rearing of prawn and fish.²¹

However, the following decade saw an important intervention in the increasing industrialization of the region, sparked by citizens and nature groups in Singapore who saw the ecological value of preserving the region. In 1986, the Singapore Branch of the Malayan Nature Society called on the government to preserve what was left of the reserve, and an appreciation for Sungei Buloh in particular shot into the public imagination. After a long campaign to restore and preserve the important biodiversity of the region while providing recreational naturespace to citizens, the Singapore government began the development of the Sungei Buloh Nature Park in 1990.²² The construction of the park took three years, and was inaugurated by the then-prime minister Goh Chok Tong in late 1993.²³ By 2002, the park’s popularity and apparent ecological importance led to its expansion from 87 to a whopping 130 hectares, becoming Singapore’s first wetlands reserve. The newly renamed Sungei Buloh Wetland Reserve attempted to restore the parts of the region that were disturbed through the strategic replanting of local species,²⁴ and by 2003 became listed as an ASEAN Heritage Park.²⁵ The Sungei Buloh Wetland Reserve boasts a commitment to “the conservation of the wetland through conservation, research, education, and recreation,”²⁶ and continues to attract numerous visitors to this day.

Discursively, the area can be understood as a site of contention regarding how land should be used in Singapore—countless arguments, debates, and letters by citizens and government agencies alike over the decades have put forth their own ideas towards how Singapore should balance nature and urban development in this particular site, perhaps precisely because this site has undergone so many changes in the past few decades. Northwestern Singapore seems to continue to pose the question: what exactly does it mean to be a Garden City? The spirit of change continues to affect the region even today, with the most recent announcement that farms in Lim Chu Kang and Kranji will be shut down in order to gazette more land to the Singapore military.²⁷ From railways to urban development, from local farms to military zones, the region can almost be thought of as a national sandbox—a kind of experimental site that sits at the whims of policy and change. These changes to the region have made it a prime location for the introduction of new species. While this kind of land reserve is useful for Singapore’s national development, ecological perspectives point towards the kinds of life—like this unobtrusive frog—that exist at the edges.

Changed landscapes thus figure into the story of the Günther’s frog in rather important ways. Not only is there a story about ornamentation—about fashionable botany and stylish greenery—but also about histories of land-use change. It seems to me no coincidence that the name ‘Sungei Buloh’, meaning ‘river of bamboo’ in Malay, is rather ironic, since the site hosts neither a river nor an established bamboo species. A nature education group based in Kranji notes that “there is a possibility of presence of bamboo in the area in the past but not now.”²⁸ While the site aims to preserve a kind of ecological heritage of Singapore, it is also clear that the region itself has been changed in indelible ways over the course of its many changes throughout the years. The notion of what constitutes a ‘natural habitat’ is thus complicated, and the quiet presence of the Günther’s frog is a testament to the multi-layered processes that make, unmake, and remake landscapes and habitats.