Thai National Parks

Snakes of Thailand

Species of Thailand

Oriental rat snake

In Thai: งูสิงหางลาย, ngu sing hang lai

Binomial name: Ptyas mucosa, Carolus Linnaeus, 1758

Ptyas mucosa, commonly known as the oriental ratsnake, Indian rat snake, or dhaman, is a common species of colubrid snake found in parts of South and Southeast Asia. Dhamans are large snakes, growing to 2 m and occasionally even to 3 m. Their colour varies from pale browns in dry regions to nearly black in moist forest areas. Dhamans are diurnal, semi-arboreal, non-venomous, and fast-moving. Dhamans eat a variety of prey and are frequently found in urban areas where rodents thrive. The species is also known as দেশাল দারাশ সাপ (Deshal darash sap) in Bengali, ගැරඩියා (geradiya) in Sinhala (Sri Lanka) and ngu sing hang lai in Thai (Thailand), in Kannada language ಜೇರೋತನ(Jerothana), Jerri pothu or Joru pothu( in.Telugu language), Sara paambu( in Tamil language).

Geographic range

Afghanistan, Bangladesh, Burma (Myanmar), Cambodia,

China (Zhejiang, Hubei, Jiangxi, Fujian, Guangdong, Hainan, Guangxi, Yunnan, Tibet, Hong Kong), India, Sri Lanka, Indonesia (Sumatra, Java), Iran, Laos, West Malaysia, Nepal, Myanmar, Pakistan (Sindh area), Taiwan, Thailand, Turkmenistan, Vietnam

Type locality: India.


Adult dhamans have few natural enemies other than the king cobras that overlap them in range. Juveniles fear birds of prey, larger reptiles, and mid-sized mammals. They are wary, quick to react, and fast-moving.

Dhamans 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 often go 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 Indian Rock Python.


Dhamans, though harmless to humans, are fast-moving, excitable snakes. In captivity individuals remain highly territorial and may continue to defend their turf aggressively, attempting to startle or strike at passing objects. Dhamans are diurnal and semiarboreal. 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.

Dhamans 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 is then 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, the proper form of the species name is mucosa. 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)
  • Ptyas mucosus, Leonhard Hess Stejneger (1907)
  • Zamenis mucosus, George Albert Boulenger (1893)
  • Zamenis mucosus, George Albert Boulenger (1890)
  • Ptyas mucosus, Albert Charles Lewis Günther (1864)
  • Ptyas mucosus, Edward Drinker Cope (1861)
  • Leptophis trifrenatus, Edward Hallowell (1861)
  • Coryphodon blumenbachii, André Marie Constant Duméril & Gabriel Bibron (1854)
  • Ptyas blumenbachii, Leopold Fitzinger (1843)
  • Coluber dhumna, Theodore Edward Cantor (1839)
  • Coluber blumenbachii, Blasius Merrem (1820)
  • Natrix mucosa, Josephus Nicolaus Laurenti (1768)
  • Coluber mucosus, Carolus Linnaeus (1758)


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 Lat District, Phetchaburi
  • Bang Phli District, Samut Prakan
  • Bangkok Province
  • Cha-Am District, Phetchaburi
  • Chom Bueng District, Ratchaburi
  • Dong Charoen District, Phichit
  • Hat Yai District, Songkhla
  • Hua Hin District, Prachuap Khiri Khan
  • Huai Kha Khaeng Wildlife Sanctuary
  • Kaeng Krachan District, Phetchaburi
  • Kaeng Krachan National Park
  • Kantharalak District, Sisaket
  • Kantharawichai District, Maha Sarakham
  • Kathu District, Phuket
  • Khao Saming District, Trat
  • Khao Yai National Park
  • Khlong Khlung District, Kamphaeng Phet
  • Klaeng District, Rayong
  • Ko Samui District, Surat Thani
  • Lam Luk Ka District, Pathum Thani
  • Lom Kao District, Phetchabun
  • Mae Poen District, Nakhon Sawan
  • Mae Rim District, Chiang Mai
  • Mu Ko Samet National Park
  • Mueang Chiang Mai District, Chiang Mai
  • Mueang Chumphon District, Chumphon
  • Mueang Maha Sarakham District, Maha Sarakham
  • Mueang Nakhon Phanom District, Nakhon Phanom
  • Mueang Nakhon Ratchasima District, Nakhon Ratchasima
  • Mueang Phetchabun District, Phetchabun
  • Mueang Phetchaburi District, Phetchaburi
  • Mueang Phichit District, Phichit
  • Mueang Phuket District, Phuket
  • Mueang Rayong District, Rayong
  • Mueang Roi Et District, Roi Et
  • Mueang Sa Kaeo District, Sa Kaeo
  • Mueang Udon Thani District, Udon Thani
  • Na Khu District, Kalasin
  • Nam Nao National Park
  • Nong Bua District, Nakhon Sawan
  • Nong Bua Rawe District, Chaiyaphum
  • Nong Kung Si District, Kalasin
  • Pak Thong Chai District, Nakhon Ratchasima
  • Pathio District, Chumphon
  • Phimai District, Nakhon Ratchasima
  • Phlapphla Chai District, Buriram
  • Phon District, Khon Kaen
  • Phu Luang District, Loei
  • Phu Wua Wildlife Sanctuary
  • Phuket Province
  • Phutthamonthon District, Nakhon Pathom
  • Rattanaburi District, Surin
  • Sai Yok District, Kanchanaburi
  • Sam Roi Yot District, Prachuap Khiri Khan
  • Sangkha District, Surin
  • Sawang Daen Din District, Sakon Nakhon
  • Sop Moei District, Mae Hong Son
  • Sung Noen District, Nakhon Ratchasima
  • Tha Yang District, Phetchaburi
  • Tham Pha Tha Phon Non-Hunting Area
  • Thanyaburi District, Pathum Thani
  • Ubolratana District, Khon Kaen
  • Wang Nuea District, Lampang
  • Wiang Pa Pao District, Chiang Rai
Range map of Ptyas mucosa in Thailand