Thai National Parks

Species of Thailand

Oriental rat snake

Ptyas mucosa

(Carolus Linnaeus, 1758)

In Thai: งูสิงหางลาย, ngu sing hang lai

Ptyas mucosa, commonly known as the Oriental rat snake, dhaman or Indian rat snake, is a common non-venomous species of colubrid snake found in parts of South and Southeast Asia. Dhamans are large snakes. Typical mature total length is around 1.5 to 1.95 m though some exceed 2 m. The record length for this species was 3.7 m, second only to their cousin Ptyas carinata among living colubrid snakes. Despite their large size, oriental ratsnakes are usually quite slender with even a specimen of 2 m commonly measuring 4 to 6 cm only around in diameter. Furthermore, the average weight of ratsnakes caught in Java was around 877 to 940 g, though larger males of over 2.3 m (which average mildly larger of the two sexes in the species) may easily weigh over 2.5 kg. Their color varies from pale browns in dry regions to nearly black in moist forest areas. Rat snakes are diurnal, semi-arboreal, non-venomous, and fast-moving. Rat snakes eat a variety of prey and are frequently found in urban areas where rodents thrive.

Geographic range

Found in Afghanistan, Bangladesh, Myanmar, Cambodia, China (Zhejiang, Hubei, Jiangxi, Fujian, Guangdong, Hainan, Guangxi, Yunnan, Tibet, Hong Kong), Taiwan, India (including Andaman and Nicobar Islands), Sri Lanka, Indonesia (Sumatra, Java, Bali), Iran, Laos, West Malaysia, Nepal, Myanmar, Pakistan (Sindh area), Thailand, Turkmenistan and Vietnam.


Adult rat snakes have no natural predators, although younger specimens are the natural prey of King cobras that overlap them in their range. Juveniles fear birds of prey, larger reptiles, and mid-sized mammals. They are wary, quick to react, and fast-moving.

Rat snakes and related colubrids are aggressively hunted by humans in some areas of their range for skins and meat. Harvesting and trade regulations exist in China and Indonesia, but these regulations are often ignored.


Description from Boulenger's Fauna of British India: Reptilia and Batrachia volume of 1890:

Snout obtuse, slightly projecting; eye large; rostral a little broader than deep, visible from above; suture between the internasals shorter than that between the prefrontals; frontal as long as its distance from the end of the snout, as long as the parietals or slightly shorter; usually three loreals; one large preocular, with a small subocular below; two postoculars; temporals 2+2; 8 Upper labials, fourth and fifth entering the eye; 5 Lower labials in contact with the anterior chin shields, which are shorter than the posterior; the latter in contact anteriorly. Dorsal scales in 17 rows at midbody, more or less strongly keeled on the posterior part of the body. Ventrals 190–208; anal divided; subcaudals 95–135, divided. Brown above, frequently with more or less distinct black crossbands on the posterior part of the body and on the tail; young usually with light crossbands on the front half of the body. Lower surface yellowish; the posterior ventral and the caudal shields may be edged with black.

It is the second largest snake in Sri Lanka, after the Indian rock python.


Rat snakes, though harmless to humans, are fast-moving, excitable snakes. In captivity, they are territorial and may defend their turf aggressively, attempting to startle or strike at passing objects. Rat snakes are diurnal and semi-arboreal. They inhabit forest floors, wetlands, rice paddies, farmland, and suburban areas where they prey upon small reptiles, amphibians, birds, and mammals. Adults, unusually for a colubrid, prefer to subdue their prey by sitting on it rather than by constricting, using body weight to weaken prey.

Rat snakes mate in late spring and early summer, though in tropical areas reproduction may take place year round. Males establish boundaries of territory using a ritualised test of strength in which they intertwine their bodies. The behaviour is sometime misread by observers as a "mating dance" between opposite-sex individuals. Females produce 6–15 eggs per clutch several weeks after mating.

Adult members of this species emit a growling sound and inflate their necks when threatened. This adaptation may represent mimicry of the king cobra or Indian cobra which overlaps this species in range. The resemblance often backfires in human settlements, though, as the harmless animal may be mistaken for a venomous snake and killed.


The International Code for Zoological Nomenclature (ICZN) directs that the grammatical gender of any given species name should follow logically from the gender of its associated genus name. As Ptyas is a feminine word form (from πτυάς, a Greek word for a venom-spitting snake), the proper form of the species name is mucosa (a Late Latin word meaning "slimy"). Reference materials older than 2004 often show the masculine form, mucosus, and the CITES list continues to list the species this way.

This article uses material from Wikipedia released under the Creative Commons Attribution-Share-Alike Licence 3.0. Eventual photos shown in this page may or may not be from Wikipedia, please see the license details for photos in photo by-lines.

Site notes

Alathough found all over the country, P. mucosa is more common in north, found less in South Thailand.

Scientific classification

Ptyas mucosa

Common names

  • German:
    • Gebänderte Rattenschlange
    • Asiatische Rattenschlange
  • English:
    • Common rat snake
    • Oriental rat snake
    • Dhaman
  • Thai:
    • งูสิงหางลาย, ngu sing hang lai
    • งูสิงคาน, ngu sing khan


  • Ptyas mucosa, Van Stanley Bartholomew Wallach et al. (2014)
  • Ptyas mucosus, R. C. Sharma (2004)
  • Ptyas mucosa, Patrick David & Indraneil Das (2004)
  • Ptyas mucosus, Theadora Pinou & Herndon Glenn Dowling (2000)
  • Coluber mucosus, James Draper Lazell (1998)
  • Ptyas mucosus, Merel J. Cox et al. (1998)
  • Ptyas mucosus, Ulrich Manthey & Wolfgang Grossmann (1997)
  • Ptyas mucosus maximus, Paul E. Pieris Deraniyagala (1955)
  • Ptyas mucosus, Malcolm Arthur Smith (1943)
  • Zaocys mucosus, Frank Wal (1921)

Conservation status

Least Concern (IUCN 3.1)

Least Concern (IUCN 3.1)


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Ptyas mucosa - Kaeng Krachan District, Phetchaburi
Ptyas mucosa - Kaeng Krachan District, Phetchaburi
Ptyas mucosa - Kaeng Krachan District, Phetchaburi
Ptyas mucosa

Range Map

Distribution map of Oriental rat snake, Ptyas mucosa in Thailand
  • Bamnet Narong District, Chaiyaphum
  • Ban Chang District, Rayong
  • Ban Dung District, Udon Thani
  • Ban Lat District, Phetchaburi
  • Ban Mo District, Saraburi
  • Ban Na District, Nakhon Nayok
  • Ban Pong District, Ratchaburi
  • Ban Tak District, Tak
  • Bang Bon District, Bangkok
  • Bang Bua Thong District, Nonthaburi
  • Bang Klam District, Songkhla
  • Bang Mun Nak District, Phichit
  • Bang Phli District, Samut Prakan
  • Bang Sao Thong District, Samut Prakan
  • Bang Saphan District, Prachuap Khiri Khan
  • Bang Saphan Noi District, Prachuap Khiri Khan
  • Bang Yai District, Nonthaburi
  • Bangkok Province
  • Cha-Am District, Phetchaburi
  • Chai Badan District, Lopburi
  • Chok Chai District, Nakhon Ratchasima
  • Chom Bueng District, Ratchaburi
  • Chum Phae District, Khon Kaen
  • Chum Ta Bong District, Nakhon Sawan
  • Dan Chang District, Suphan Buri
  • Dan Khun Thot District, Nakhon Ratchasima
  • Doi Saket District, Chiang Mai
  • Don Mueang District, Bangkok
  • Dong Charoen District, Phichit
  • Erawan District, Loei
  • Hat Yai District, Songkhla
  • Hua Hin District, Prachuap Khiri Khan
  • Hua Sai District, Nakhon Si Thammarat
  • Huai Kha Khaeng Wildlife Sanctuary
  • Huai Mek District, Kalasin
  • Kabin Buri District, Prachinburi
  • Kaeng Hang Maeo District, Chanthaburi
  • Kaeng Khoi District, Saraburi
  • Kaeng Khro District, Chaiyaphum
  • Kaeng Krachan District, Phetchaburi
  • Kaeng Krachan National Park
  • Kamphaeng Saen District, Nakhon Pathom
  • Kantharalak District, Sisaket
  • Kantharawichai District, Maha Sarakham
  • Kap Choeng District, Surin
  • Kathu District, Phuket
  • Kham Muang District, Kalasin
  • Khanu Woralaksaburi District, Kamphaeng Phet
  • Khao Khitchakut District, Chanthaburi
  • Khao Laem Ya - Mu Ko Samet National Park
  • Khao Saming District, Trat
  • Khao Yai National Park
  • Khlong Khlung District, Kamphaeng Phet
  • Khlong Luang District, Pathum Thani
  • Khlong Sam Wa District, Bangkok
  • Khlung District, Chanthaburi
  • Khon San District, Chaiyaphum
  • Khon Sawan District, Chaiyaphum
  • Klaeng District, Rayong
  • Ko Samui District, Surat Thani
  • Kumphawapi District, Udon Thani
  • Lam Luk Ka District, Pathum Thani
  • Laplae District, Uttaradit
  • Lat Krabang District, Bangkok
  • Lat Phrao District, Bangkok
  • Lom Kao District, Phetchabun
  • Mae Ai District, Chiang Mai
  • Mae On District, Chiang Mai
  • Mae Poen District, Nakhon Sawan
  • Mae Rim District, Chiang Mai
  • Mae Sot District, Tak
  • Makham District, Chanthaburi
  • Mancha Khiri District, Khon Kaen
  • Manorom District, Chainat
  • Min Buri District, Bangkok
  • Mueang Chachoengsao District, Chachoengsao
  • Mueang Chaiyaphum District, Chaiyaphum
  • Mueang Chanthaburi District, Chanthaburi
  • Mueang Chiang Mai District, Chiang Mai
  • Mueang Chonburi District, Chonburi
  • Mueang Chumphon District, Chumphon
  • Mueang Kalasin District, Kalasin
  • Mueang Kamphaeng Phet District, Kamphaeng Phet
  • Mueang Khon Kaen District, Khon Kaen
  • Mueang Lampang District, Lampang
  • Mueang Lopburi District, Lopburi
  • Mueang Maha Sarakham District, Maha Sarakham
  • Mueang Nakhon Nayok District, Nakhon Nayok
  • Mueang Nakhon Phanom District, Nakhon Phanom
  • Mueang Nakhon Ratchasima District, Nakhon Ratchasima
  • Mueang Nakhon Sawan District, Nakhon Sawan
  • Mueang Nongbua Lamphu District, Nong Bua Lamphu
  • Mueang Nonthaburi District, Nonthaburi
  • Mueang Phatthalung District, Phatthalung
  • Mueang Phetchabun District, Phetchabun
  • Mueang Phetchaburi District, Phetchaburi
  • Mueang Phichit District, Phichit
  • Mueang Phitsanulok District, Phitsanulok
  • Mueang Phuket District, Phuket
  • Mueang Prachinburi District, Prachinburi
  • Mueang Ratchaburi District, Ratchaburi
  • Mueang Rayong District, Rayong
  • Mueang Roi Et District, Roi Et
  • Mueang Sa Kaeo District, Sa Kaeo
  • Mueang Samut Prakan District, Samut Prakan
  • Mueang Samut Sakhon District, Samut Sakhon
  • Mueang Samut Songkhram District, Samut Songkhram
  • Mueang Saraburi District, Saraburi
  • Mueang Sing Buri District, Sing Buri
  • Mueang Surat Thani District, Surat Thani
  • Mueang Surin District, Surin
  • Mueang Trang District, Trang
  • Mueang Trat District, Trat
  • Mueang Udon Thani District, Udon Thani
  • Na Khu District, Kalasin
  • Na Thom District, Nakhon Phanom
  • Na Yai Am District, Chanthaburi
  • Nakhon Chai Si District, Nakhon Pathom
  • Nam Nao National Park
  • Nam Som District, Udon Thani
  • Noen Maprang District, Phitsanulok
  • Non Daeng District, Nakhon Ratchasima
  • Nong Bua District, Nakhon Sawan
  • Nong Bua Rawe District, Chaiyaphum
  • Nong Chok District, Bangkok
  • Nong Kung Si District, Kalasin
  • Nong Phai District, Phetchabun
  • Nong Ruea District, Khon Kaen
  • Pa Sang District, Lamphun
  • Pak Kret District, Nonthaburi
  • Pak Thong Chai District, Nakhon Ratchasima
  • Pathio District, Chumphon
  • Phak Hai District, Phra Nakhon Si Ayutthaya
  • Phen District, Udon Thani
  • Phimai District, Nakhon Ratchasima
  • Phlapphla Chai District, Buriram
  • Phon District, Khon Kaen
  • Phrai Bueng District, Sisaket
  • Phu Khiao District, Chaiyaphum
  • Phu Luang District, Loei
  • Phu Wua Wildlife Sanctuary
  • Phuket Province
  • Phutthamonthon District, Nakhon Pathom
  • Pla Pak District, Nakhon Phanom
  • Plaeng Yao District, Chachoengsao
  • Pluak Daeng District, Rayong
  • Pran Buri District, Prachuap Khiri Khan
  • Prathai District, Nakhon Ratchasima
  • Prawet District, Bangkok
  • Rattanaburi District, Surin
  • Saba Yoi District, Songkhla
  • Sadao District, Songkhla
  • Sai Mai District, Bangkok
  • Sai Noi District, Nonthaburi
  • Sai Yok District, Kanchanaburi
  • Sam Phran District, Nakhon Pathom
  • Sam Roi Yot District, Prachuap Khiri Khan
  • Sangkha District, Surin
  • Sankhaburi District, Chainat
  • Sao Hai District, Saraburi
  • Saphan Sung District, Bangkok
  • Sapphaya District, Chainat
  • Sathing Phra District, Songkhla
  • Sawang Daen Din District, Sakon Nakhon
  • Sawi District, Chumphon
  • Selaphum District, Roi Et
  • Sena District, Phra Nakhon Si Ayutthaya
  • Si Racha District, Chonburi
  • Si Samrong District, Sukhothai
  • Si Somdet District, Roi Et
  • Si Thep District, Phetchabun
  • Sida District, Nakhon Ratchasima
  • Sikhio District, Nakhon Ratchasima
  • Sing Buri Province
  • Singhanakhon District, Songkhla
  • Song Phi Nong District, Suphan Buri
  • Sop Moei District, Mae Hong Son
  • Suan Luang District, Bangkok
  • Suan Phueng District, Ratchaburi
  • Sung Noen District, Nakhon Ratchasima
  • Tak Fa District, Nakhon Sawan
  • Tha Maka District, Kanchanaburi
  • Tha Sae District, Chumphon
  • Tha Song Yang District, Tak
  • Tha Takiap District, Chachoengsao
  • Tha Wung District, Lopburi
  • Tha Yang District, Phetchaburi
  • Tham Pha Tha Phon Non-Hunting Area
  • Thanyaburi District, Pathum Thani
  • Thawi Watthana District, Bangkok
  • Thong Pha Phum District, Kanchanaburi
  • Thung Yai District, Nakhon Si Thammarat
  • Thung Yai Naresuan Wildlife Sanctuary
  • U Thong District, Suphan Buri
  • Ubolratana District, Khon Kaen
  • Uthai District, Phra Nakhon Si Ayutthaya
  • Wang Hin District, Sisaket
  • Wang Noi District, Phra Nakhon Si Ayutthaya
  • Wang Nuea District, Lampang
  • Wanon Niwat District, Sakon Nakhon
  • Wiang Pa Pao District, Chiang Rai
  • Wihan Daeng District, Saraburi
Range map of Ptyas mucosa in Thailand