Sibynophis collaris, the gentle Common Blackhead

blackhead

A common blackhead from Umphang district, Tak.

Genus Sibynophis (blackheads)

The snakes of this genus are also known as many-toothed snakes, as their maxilla bear many tiny teeth (35-50 in each), which are closely set and almost equal in size.

There are other peculiarities in the dentition, while modifications of the jaws may have some special significance in aiding the snake to engulf their food.

As they largely subsist upon skinks, it may be that independent movements of the toothed bones permit the snake to grasp these smooth, rounded and tough-skinned animals in a viselike manner at any one moment with three of its four dentaries while the fourth is moved forward to a new position, an explanation first offered by Karl Patterson Schmidt. (1)
Three species occur in Thailand, but only the Common Blackhead is known from northern Thailand.

blackhead Nam Pat

Dorsal view of the anterior part of a Common Blackhead from Nam Pat district, Uttaradit.

Common blackhead (Sibynophis collaris)

Thai name: ngu kho khwan hua dam – งูคอขวั้นหัวดำ

This handsome, little to medium-sized snake lives in evergreen forests at elevations over 700 meter a.s.l., where it is usually hidden in the litter or undergrowth. It reaches a length of 75 cm, the tail being long, about 35 percent of the total length.

The slender body is cylindrical, the head is hardly differentiated from the neck. The back is olive brown anteriorly, slightly more reddish brown in the central part of the body, whereas posteriorly, including the tail, it is a dark greyish brown.

A very faint, rather broad lateral band may run from the neck to the tail, just a shade lighter than the basic colour. A line of tiny black dots runs over the vertebral ridge, while there may be a rather inconspicuous lateral line of tiny light spots.
The dorsal scales are smooth.

head blackhead

Details of the head of a specimen from Umphang district, Tak.

The belly is light yellow with two rows of black dots on the edges of the ventral scales.
Anteriorly these are small and rounded.
Posteriorly they are large and rectangular and almost continuous with the brown colour of the dorsum.

The throat is white, but in many specimens it can be orange — in the latter case it is continuous with the orange border of the collar.

The subcaudals are paired.

The head is dark grey with usually two black crossbars.

Behind the head is a black nape with an orange border on the backside.

The supralabials (scales of the upper lip) are white, except for the edges, forming a white band.

The relative large, dark eye has a round pupil with a narrow orange edge.
The tongue is dark grey.

hemipenis

Hemipenis of a specimen from Umphang district, Tak; it bears a few large spines and numerous small ones.

hemipenis and throat

View of belly, vent and hemipenis (above) and the throat (below) of another, more colourful specimen.

The hemipenis has 5-6 large spines and numerous small spines.

The dark colour of the head probably improves camouflage, or may help to absorb heat from the sun rays in order to warm up the brain and to propel the animal into activity.

This snake is predominantly terrestrial and diurnal.

Skinks seem to be the principal food it takes, but it is also known to prey upon other snakes (2), frogs and insects.
Females are known to produce up to six eggs. (3)

It occurs widely and is rather common, and one can come across it  in virtually all evergreen forests at elevations of over 700 meter a.s.l.

It has also been recorded from forested areas adjacent to the North, such as in Kanchanaburi province and parts of the Northeast-Thailand (4), and from the South.
Beside Thailand, it is known from peninsular Malaysia (5), Indochina, Myanmar, Bangladesh, northern India and Nepal. (6)

©SJON HAUSER: text, pictures and map.


map

Black dots: places where I came across the common blackhead.

montane forest

Montane forest with tree-ferns in Umphang district, Tak, where this species thrives.

Notes:

1. Alan E. Leviton, 1963. Contributions to a review of Philippine snakes, II. The snakes of the genera Liopeltis and Sibynophis. The Philippine Journal of Science 92 (4): 367-381. (p.374-376)

2. As was reported by F. Wall early in the 20th century for an Indian specimen. In: R. C. Sharma, 2003. Handbook Indian Snakes. Zoological Survey of India, Kolkata: 130.

3. Merel J. Cox, Peter Paul van Dijk, Jarujin Nabhitabhata, and Kumthorn Thirakhupt,1998. A Photographic Guide to Snakes and other Reptiles of Thailand and South-East Asia. Asia Books, Bangkok: 57; Indraneil Das, 2002. A Photographic Guide to Snakes and other Reptiles of India. New Holland Publishers, London: 45.

4. Merel J. Cox, 1991. The Snakes of Thailand and their Husbandry. Krieger, Malabar, Florida: 278-79.

5. M. W. F. Tweedie, 1953: The Snakes of Malaya. Government Printing Office, Singapore: 64.

6. Cox, 1991, ibid.: 279; Indraneil Das, 2010. A Field Guide to the Reptiles of Thailand and South-East Asia. Asia Books, Bangkok: 301.