Crocodylus porosus Schneider, 1801

Figueroa, Alex, Low, Martyn E. Y. & Lim, Kelvin K. P., 2023, Singapore’s herpetofauna: updated and annotated checklist, history, conservation, and distribution, Zootaxa 5287 (1), pp. 1-378 : 63-66

Crocodylus porosus Schneider, 1801 — Native.

Crocodilus porosus Schneider, 1801: 159–160 . Lectotype: ZMB 278, designated by Wermuth (1954: 485); paralectotypes (2): ZFMK 40955–56, according to B̂hme (2010: 107); type material as “cited by Schneider (1801) included this specimen [lectotype] from the Bloch collection, three specimens from the Ĝttingen Museum [the two paralectotypes], and specimens figured by Seba (1734: pl. 104, fig. 12) and Knorr (1766: vol. 2: pl. 5, fig. 4)” according to Bauer & Ģnther (2006: 245). Type locality: None stated/traced; later designated as “the East Indies” by Deraniyagala (1939: 278); later restricted to “ India ” via lectotype designation; later restricted to “Mainland of Hither India ” by Wermuth (1960: 26); later restricted to “ Ceylon ” (= Sri Lanka) by Mertens (1960: 271).

Estuarine Crocodile

( Figure 7G )

Singapore records.

Crocodilus porosus — Cantor, 1847a: 622.— Cantor, 1847c: 1067.— Boulenger, 1889a: 285.— Flower, 1896: 862 (Pandan River; Serangoon).— Hanitsch, 1898: 9.— Flower, 1899: 623, 625 (Tanjong Pagar Wharf [= Tanjong Pagar Terminal]).—Ridley, 1899: 189.—Hanitsch, 1908: 40.— Hanitsch, 1912b: 14.— de Rooij, 1915: 337–338.—D.S. Johnson, 1964: 25 (Jurong-Pandan Area).— Chuang, 1973: 3.— Harrison & Tham, 1973: 253.—L.M. Chou et al., 1980: 71.—L.M. Chou & T.J. Lam, 1989: 92.—D.S. Johnson, 1992: 34.

“Alligators”—Oxley, 1849: 596.

“[A]lligators”— Crawfurd, 1856: 398.

Crocodilus biporcatus —M̧ller, 1878: 749.

“Crocodile”— Knight, 1887: 99 (“Ponggol-river” [= Sungei Punggol]).— Moulton, 1922: 567 (Pandan River).—K. Lim, 1989h: 40.—M.E.Y. Low & Pocklington, 2019: 20.

Crocodylus porosus —Sharma, 1973: 233.—F.L.K. Lim, 1984: 18.— Gremli, 1988: 62.—K. Lim & F. Lim, 1988c: 75 (Woodlands).—K. Lim, 1989e: 39 (Sungei Seletar Reservoir).—K. Lim, 1990a: 11 (Sungei Buloh Bird Sanctuary [= SBWR]).—K.K.P. Lim & L.M. Chou, 1990: 56.—K.K.P. Lim, 1991a: 4 (Sungei Seminei [Pulau Tekong]).—K.K.P. Lim & F.L.K. Lim, 1992: 123–124, 151.— K.K.P. Lim & Subharaj, 1992: 9 (Kranji Reservoir; Marina East).—P.K.L. Ng, 1992a: 143.—P.K.L. Ng, 1992b: 143.—L.M. Chou et al., 1994: 105.—K.K.P. Lim, 1994b: 224, 331.—J.K.Y. Low et al., 1994: 158.—K. Lim, 1995: 19 (Johor Straits [Woodlands]; Pulau Seletar; Punggol Estuary).— P.K.L. Ng et al., 1995: 124.—R. Subaraj, 1995: 33, 36 (Pulau Ubin).—R.C.H. Teo & Rajathurai, 1997: 392 (MacRitchie Reservoir; Upper Seletar Reservoir).—Sharma, 1998: 149.—Chan-ard et al., 1999: 41.—P.K.L. Ng & Sivasothi, 1999: 147.—K.P. Lim & F.L.K. Lim, 2002: 151.— Anonymous, 2003: 32, 93 (Sungei Buloh Wetland Reserve).—E.K. Chua, 2007b: 165.—K.K.P. Lim et al., 2008: 173, 266 (Kallang River Estuary; Kranji Reservoir; Pulau Tekong; Singapore River Estuary; Seletar Reservoir; Sungei Buloh Wetland Reserve).—N. Baker & K.P. Lim, 2008: 121, 159.— Das, 2010: 166.—P.K.L. Ng et al., 2008: 170.—T.H. Ng & K.K.P. Lim, 2010: 119 (Lower Seletar Reservoir; Sarimbun Reservoir).—H.T.W. Tan et al., 2010: 1117.—Webb et al., 2010: 99.—L.M. Chou, 2011: 75.—M.A.H. Chua, 2011: 278 (Semakau Landfill [PS]).—P.K.L. Ng et al., 2011: 281.—N. Baker & K.P. Lim, 2012: 121, 159.— Davison et al., 2012: 88.— Jaafar et al., 2012: 82.—M.F.C. Ng, 2012: 146.—M. Ng & Mendyk, 2012: 34–37 (Sungei Buloh Wetland Reserve).—The Straits Times, 2014 (East Coast Park; “Strait of Johor off Admiralty Road”; Sungei Buloh [= SBWR]; Sungei Seletar Reservoir [= LS]; Tampines River canal [= Sungei Tampines]).— Chan-ard et al., 2015: 296.—T. Lim, 2015: 36 (Sungei Buloh Wetland Reserve).—K.K.P. Lim, 2016: 176 (Pulau Tekong).—L. Lam, 2017 (National Sailing Centre [= ECP]).—A. Tan, 2017 (Sungei Tampines).—W. Wong, 2017: 81.— Fukuda et al., 2018: 812.—M.L. Kwak et al., 2019a: 128 (Sungei Buloh Wetland Reserve).—M.E.Y. Low & Pocklington, 2019: 192.—Mumpuni et al., 2019: 85.—Pocklington, 2019: 5–24 (Kallang River; Lim Chu Kang; Potong Pasir; Punggol; “Rochore” River; Sungei Kadut; Whampoa River).— Begum, 2019 (Sungei Kadut).—Z. Tee, 2019b (Lower Seletar Reservoir).—J. Aw & M.E.Y. Low, 2020: 26.—Pocklington, 2021: 46–70 (“14th mile, East Coast” [= Changi]; Anson Road; Arthur Road; Balai Quarry, Pulau Ubin; Berlayer Hill [= LNR]; “Between Fairy Point and Pulo Obin” [= SJ]; Boon Lay Road [= Jalan Boon Lay]; Botanic Gardens Lake [= Swan Lake, SBG]; Bukit Chermin; Bukit Sembawang; “Canal alongside Campong Java Road” [= Sungei Rochor]; Causeway, Johore Straits [= SJ]; Central Beach, Sentosa [= Pulau Blakang Mati]; “Chan Chu-Kang, Selitar” [= Sungei Seletar]; “Changhie” [= Changi]; Changi Beach Park; Changi Ferry [= Changi Point Ferry Terminal]; Changi Road; Chinese Garden Lake [= Jurong Lake]; Chinese Swimming Club [= Tanjong Katong]; Chua Chu Kang; Crescent Road; Dalhousie Pier [= Asian Civilisations Museum Green]; “Diving stage, Swimming Club” [= Tanjong Rhu]; East Coast beach [= ECP]; Esplanade; Fort Road; Garden Club, Katong [= Tanjong Katong]; Gaylang [= Geylang]; Gaylang River [= Sungei Geylang]; Geylang Swamp, Grove Estate [= Chung Cheng Lake]; Harbour [= Keppel Harbour]; “Harbour, Master Attendant’s pier” [= Collyer Quay]; Impounding Reservoir [= MacRitchie Reservoir]; “In river close to Adamson, Gilfilan and Co’s godown” [= Collyer Quay]; “In sea off the Causeway” [= SJ]; Jalan Teck Whye; Johor Strait [= SJ]; “Johore Straits near Kranji” [= SJ]; “Johore Straits near Senoko Way” [= SJ]; Jurong; Jurong Lake; Jurong Prawn Ponds [= Sungei Jurong]; Jurong River [= Sungei Jurong]; Jurong Road; Kallang Basin [= Mountbatten Road]; Kallang District [= Kallang]; Kallang River [= Sungei Kallang]; Kampong Java Road; Kampong Pond, Kankar Fishing Village [= Sungei Serangoon]; Katong [= Tanjong Katong]; Katong Lake [= Chung Cheng Lake]; “Katong, near the Swimming Club” [= Tanjong Katong]; Katong Park; Keppel Harbour; Khatib Bongsu [= KBNP]; Kranji; Kranji Dam; “Kranji extension” (Sungei Buloh WR) [= KCNP]; Kranji Nature Trail [= KCNP]; Kranji Reservoir; Kranji River [= Sungei Kranji]; “Kranji River to Bukit Timah” [= Sungei Pang Sua]; Kranji Sports Fishing Ground [= KR]; Kranji Way; Kuala Johore [= SJ]; Lim Chu Kang; Lim Chu Kang Fish Farm; Lim Chu Kang Jetty; Lorong Chuntum [= Lor Lada Hitam]; Lorong Gambas; Lorong Halus; MacRitchie Reservoir; Marina East; Marina Reservoir ; McPherson Road; “Mouth of small river between Changie and Pasir Ris” [= Sungei Selarang]; “Mr Lim Koh Eng’s bungalow, 6¾ mile, Pasir Panjang” [= WCP]; “Muddy creek running past Ice Works at Sirangoon, 3rd milestone” [= Sungei Rochor]; “Nearby river of Jalan Gemala off Lim Chu Kang” [= Sungei Simpang Mak Wai]; Pandan River [= Sungei Pandan]; Park Road; “Pasa Labar” [= Pasir Laba]; Pasir Panjang; Pasir Panjang Beach; Pasir Panjang Road; Pasir Ris Beach; Pasir Ris Park; Ponggol [= Punggol]; Pongol [= Punggol]; Pongol Beach [= Punggol Beach]; Pongol River [= Sungei Ponggol]; Pongol Road [= Punggol Road]; Powder Magazine [= Alkaff Quay]; Pulau Buloh; Pulau Retan Laut [= Pasir Panjang Terminal]; Pulau Saigon [= Sungei Singapore]; Pulau Seletar; Pulau Tekong, Sungei Seminei [= PT]; Pulau Tekong Besar; Pulo Obin quarry [= Pekan Quarry]; Pulau Ubin Jetty; Pulo Sirimbun [= Pulau Sarimbun]; Pulo Tekong [= PT]; Punggol Estuary; Raffles Country Club; “River off Lim Chu Kang” [= Sungei Kangkar]; River Valley Road; Robertson Quay; Robinson Road; Rochore Canal [= Sungei Rochor]; Rochore River [= Sungei Rochor]; Sarimbun Reservoir; “Seabeach opposite old Fort near Swimming Club, Katong” [= Tanjong Katong]; Sea View Hotel [= Tanjong Katong]; Seletar; Seletar Reservoir; Semakau Landfill [= PS]; “Sembawang waters” [= Sembawang Park Fishing Pier]; Serangong [= Serangoon]; Serangoon River [= Sungei Serangoon]; Serangoon Swamp (near Lavender Street) [= Bendemeer]; “Side of Grove Road” [= Tanjong Rhu]; “Side of the river in Pongol” [= Sungei Serangoon]; Siglap; Singapore River [= Sungei Singapore]; Sirangoon [= Serangoon]; Sirangoon River [= Sungei Serangoon]; “Small lake in the plantation at McPherson Road” [= Potong Pasir]; “Southeastern coast line” [= Singapore Strait]; St John’s Island [= Pulau Sekijang Bendera]; Straits of Johore [= SJ]; Straits of Singapura [= SJ]; Sungei Battu Belyhar [= Berlayer Creek]; Sungei Buloh [= SBWR]; Sungei Buloh Besar; Sungei Buloh Bird’s Sanctuary [= SBWR]; Sungei Buloh Wetland Reserve; Sungei Jurong; Sungei Jurong Road [= Jurong Canal Drive]; Sungei Kadut; Sungei Kechil, Serangoon Road [= Sungei Whampoa]; Sungei Kranji; Sungei Pandan; Sungei Seletar Reservoir [= Lower Seletar Reservoir]; Sungei Sembawang; Sungei Tampines; “Swamp near 6th milestone, Swimming Club” [= Tanjong Katong]; Tampines; Tampines farm; Tampines River Canal [= Sungei Tampines]; Tanglin Barracks; Thompson Road [= WNP]; Tanjong Balai [= Pulau Ubin]; Tanjong Katong; Tanjong Kling; Tanjong Pagar; Tanjong Pagar Wharf [= Tanjong Pagar Terminal]; Tanjong Rhoo [= Tanjong Rhu]; Tanjong Rhu; Telok Mata Ikan [= Changi South Ave 3]; Tengah Reservoir; Tengah Reservoir Golf Course [= Raffles Country Club]; “Thompson Road Stream” [= TRF]; Thomson Road; “Trafalgar Estate, cocoa-nut plantation” [= Buangkok]; Tuas; Tuas River [= Tengah Reservoir]; Tuas Shipyard; Ulu Pandan River [= Sungei Pandan]; Ulu Sungei Pongol [= Sungei Punggol]; Upper Seletar Reservoir; Vaughan Road; Victoria Dry Dock [= Tanjong Pagar Terminal]; West Coast Rise; West Coast Road; Whampoa River [= Sungei Whampoa]; Wilkinson Road; Woodlands Causeway; Woodlands Town Garden [= Marsiling Park]; Woodlands Town Park [= Woodlands Town Park East]; Woodlands Waterfront Park).—E.K. Chua, 2022: 57 (Sungei Buloh Wetland Reserve).— Kurniawan et al., 2022: 108.—M.L. Kwak & A. Ng, 2022: 929.

“Estuarine crocodile”—Qing, 2021 (East Coast Park).— Lean, 2022a (“Lim Chu Kang waters between S’pore & M’sia”).—Zheng, 2022a (“Choa Chu Kang canal”).

Remarks. Recently, there were two books published on crocodiles in Singapore. The first is Buayapura (Pocklington 2019), a short historical and philosophical examination of C. porosus that imparts that the first mention of crocodiles from Singapore comes from the book, Hikayat Hang Tuah, which was written between 1641 and 1739. In there, the author declared that “…the Straits of Singapura was infested with man-eating crocodiles…” (Pocklington 2019). This represents the earliest reference of any herpetofauna from Singapore, and although no specimen was collected and no description was provided, we can be assured that the identity of the species was C. porosus since it is the only native crocodilian to Singapore. The second book, Beast, Guardian, Island: The Saltwater Crocodile ( Crocodylus porosus Schneider, 1801 ) in Singapore, 1819–2017, explored human interactions with crocodiles in Singapore, and collated newspaper records between 1819 and 2017 providing the most comprehensive historical distribution and analysis for any herpetofauna species in Singapore (Pocklington 2021). Prior to the first report of C. porosus from Singapore in the scientific literature ( Cantor 1847a), Pocklington (2021) listed two additional earlier records. The first is from sometime between 1819 and 1823 and involves a crocodile Farquhar hung from a fig tree along the Rochor River that ate his dog. The second was of a crocodile that ate someone along the Rochor Canal in March 1842.

Early in history, C. porosus was considered quite abundant ( Flower 1899), but due to coastal development and a government initiative to rid Singapore of crocodiles (Sharma 1973; Pocklington 2021), this species became quite rare and was even considered extinct (Chuang 1964; Lim 1984; Webb et al. 2010). Correspondingly, the IUCN-SSC Crocodile Specialist Group assigned C. porosus as regionally extinct in Singapore in 1996 (Pocklington 2021). In the scientific literature, after Moulton (1921) reported an “ 11 ft. ” specimen that was killed in the Pandan River and donated by Choo Seng Yen, C. porosus was not reported from Singapore until 43 years later ( Table 2 ) by Johnson (1964) who described it as rare, but noted that some individuals were occasionally seen in the Jurong-Pandan area. Shortly thereafter is when Chuang (1973) classified C. porosus as extinct. Thereupon, wild individuals from the early 1990s were believed to be a mixture of escaped individuals from breeding farms and abandoned pets (Teo & Rajathurai 1997; Ng & Lim 2010). Sharma (1973) remarks that the Singapore population may have been sustained by individuals swimming over from Johor Bahru, Malaysia. However, Pocklington (2021) discloses a conflicting reality, one where C. porosus was still frequently encountered. Thus, there appears to be no credible evidence that C. porosus was ever truly extinct in Singapore (Pocklington 2021).

Although, C. porosus once occupied much of Singapore (Pocklington 2021), today the only resident population persists in SBWR. Yet, the first record from SBWR is only from November 1990 ( Lim 1990a; Pocklington 2021). On occasion, some individuals will stray away from SBWR to explore new areas such as one sighted at LS in July 1989, one seen at ECP in December 1992, one seen swimming in the Straits of Johor off Admiralty Road in June 1995, one seen at Sungei Tampines in August 2008 (The Straits Times 2014), one photographed basking along Sungei Tampines on 1 August 2017 (Tan 2017), likely the same individual seen in a drain adjacent to the National Sailing Centre at ECP on 8 November 2017, one seen at LSR on 23 February 2019 (Tee 2019b), one found in Sungei Kadut drain on 21 June 2019 ( Begum 2019), one filmed at ECP near Fort Road on 5 October 2021 (Qing 2021), and one floating in Choa Chu Kang canal on 16 May 2022 (Zheng 2022a). Given the extent of reclamation, urban development, and barriers such as dams, sluice gates, litter traps, and float booms restricting access inland along waterways, it seems unlikely that C. porosus will establish populations elsewhere in Singapore.

Occurrence. Restricted to a few confined locations. Uncommon. SBWR represents the stronghold.

Singapore conservation status. Critically Endangered.

Conservation priority. Highest.

IUCN conservation status. Least Concern [2021].

LKCNHM & NHMUK Museum specimens. Singapore (no locality) : BMNH 1883.11.28.3–12 (no date), ZRC.2.304– ZRC. 2.306 (8-22-1897); Sungei Seletar Reservoir [ USR] : ZRC.2.2556 (1988); Sungei Buloh Wetland Reserve : ZRC.2.6841– ZRC.2.6843, ZRC.2.6848 (8-Apr-2009) .

Additional Singapore museum specimens. Singapore (no locality): NMW, RBINS, ROM, SAMA, ZMB.

Singapore localities. Alkaff Quay*—Anson Road*—Arthur Road*—Asian Civilisations Museum Green*— Berlayer Creek*—Bendemeer*—Buangkok*—Bukit Chermin*—Bukit Sembawang*—Changi*— Changi Beach Park*—Changi Point Ferry Terminal*—Changi Road*—Changi South Ave 3*—Choa Chu Kang*—Chung Cheng Lake*—Collyer Quay*—Crescent Road*—East Coast Park*—Esplanade*—Fort Road*—Geylang*—Jalan Boon Lay*—Jalan Teck Whye*—Jurong*—Jurong Canal Drive*—Jurong Lake*—Jurong-Pandan Area*—Jurong Road*—Kallang*—Kampong Java Road*—Katong Park*— Keppel Harbour*—Khatib Bongsu Nature Park—Kranji—Kranji Coastal Nature Park—Kranji Dam— Kranji Reservoir*—Kranji Way—Labrador Nature Reserve*—Lim Chu Kang—Lim Chu Kang Fish Farm*—Lim Chu Kang Jetty—Lor Lada Hitam*—Lorong Gambas*—Lorong Halus*—Lower Seletar Reservoir*—MacRitchie Reservoir*—Marina East*— Marina Reservoir *—Marsiling Park*—McPherson Road*—Mountbatten Road*—Park Road*—Pasir Laba*—Pasir Panjang*—Pasir Panjang Beach*— Pasir Panjang Road*—Pasir Panjang Terminal*—Pasir Ris Beach*—Pasir Ris Park*—Pekan Quarry*— Potong Pasir*—Pulau Blakang Mati*—Pulau Buloh—Pulau Sarimbun—Pulau Sekijang Bendera*— Pulau Seletar*—Pulau Semakau*—Pulau Tekong*—Pulau Tekong Besar*—Pulau Ubin*—Pulau Ubin Jetty*—Punggol*—Punggol Beach*—Punggol Estuary*—Punggol Road*—Raffles Country Club*— River Valley Road*—Robertson Quay*—Robinson Road*—Sarimbun Reservoir*—Seletar*—Seletar Reservoir*—Sembawang Park Fishing Pier—Serangoon*—Siglap*—Singapore Botanic Gardens*— Singapore Strait*—Sungei Buloh Besar—Sungei Buloh Wetland Reserve—Sungei Geylang*—Sungei Jurong*—Sungei Kadut*—Sungei Kallang*—Sungei Kangkar*—Sungei Kechil*—Sungei Kranji*— Sungei Pandan*—Sungei Pang Sua*—Sungei Punggol*—Sungei Rochor*—Sungei Selarang*—Sungei Seletar*—Sungei Sembawang*—Sungei Serangoon*—Sungei Simpang Mak Wai*—Sungei Singapore*— Sungei Singapore Estuary*—Sungei Tampines*—Sungei Whampoa*—Straits of Johor—Tampines*— Tanglin Barracks*—Tanjong Katong*—Tanjong Kling*—Tanjong Pagar Terminal*—Tanjong Rhu*— Tengah Reservoir*—Thomson Ridge Forest*—Thomson Road*—Tuas*—Tuas Shipyard*—Upper Seletar Reservoir*—Vaughan Road*—West Coast Park*—West Coast Rise*—West Coast Road*—Wilkinson Road*—Windsor Nature Park*—Woodlands—Woodlands Causeway—Woodlands Town Park East*— Woodlands Waterfront Park*.

Order Testudinata Batsch, 1788 (17 species)

Testudines Batsch, 1788: 437 , footnote.

Family Cheloniidae Oppel, 1811 (4 species)

Chelonii Oppel 1811: 8 (type genus Chelonia Brongniart, 1800 ).

Genus Caretta Rafinesque, 1814 (1 species)

Figures

FIGURE 7. A) Pulchrana laterimaculata, B) Sylvirana guentheri, C) Leptomantis cyanopunctatus, D) Nyctixalus pictus, E) Polypedates leucomystax, F) Theloderma horridum, G) Crocodylus porosus, and H) Caretta caretta. Photographs by: Alex Figueroa [A–B, D–F], Marcus A.H. Chua [C], Jensen G.H. Seah [G], and Kelvin K.P. Lim [H].