From Tropical Topics newsletter, No. 80,
January 2004, produced by Stella Martin at the Queensland
Environmental Protection Agency. Download the PDF to read the whole
issue.
Colubrids are also known as the ‘harmless’ snakes,
although some of them do produce venom. However, this is delivered
through fangs in the rear of the mouth and is not of a strength
considered dangerous to humans. Most of the snakes in this group
live either in water or in trees. Although this family dominates
most parts of the world, in Australia colubrid snakes are
well-outnumbered by the elapids.
The common tree snake (Dendrelaphis punctulata) is
a slender, agile snake living in tropical and temperate forests,
and in vegetation close to water, along eastern Australia and
across the north.
Although it is often known as the green tree snake, this species
can vary in colour from black, brown or grey to bright green,
yellow and turquoise. It is fond of frogs but also eats small
reptiles, fish and tadpoles. It hunts on the ground and in the
trees, where it climbs and moves rapidly.
The northern tree snake, which is very similar in appearance,
apart from a dark stripe along the side of its head, inhabits the
east coast of Queensland, north from Townsville.
The brown tree snake (Boiga irregularis) does not
belong to the same genus as the other tree snakes. It is similar in
its tree-dwelling habits but possesses venom glands associated with
fangs at the back of its mouth. This is a nocturnal hunter and has
remarkably large eyes, to help its vision at night. It eats
lizards, small mammals and birds, including eggs and nestlings.
Since its accidental introduction into the Pacific island of Guam,
in the 1940s, the population of this snake has exploded and is
blamed for the extinction of 12 bird species. This is a very feisty
snake which, if confronted, reacts in a frighteningly aggressive
manner. Although it is not considered harmful to people, many small
children in Guam have been treated for bites. Brown tree snakes are
found across northern Australia and in the east, north of about
Sydney. Those west of the Gulf of Carpentaria, tend to be strongly
banded, whereas those in the east have much less distinctive
markings and are considered, by some, to be a different
species.
The white-bellied mangrove snake (Fordonia
leucobalia) inhabits the coastal fringe of Australia, living in
crab-holes in the mangrove mud. It crawls around the mud at night
feeding largely on crustaceans. Mangrove snakes are the only snakes
known to dismember prey before eating. When catching a crab, this
snake leaps over it and presses it down against the mud, or a
harder surface. It bites its prey, using venom from the fangs in
the rear of its mouth to immobilise it and then, keeping its victim
pinned down, tears off its legs. Small crabs are swallowed whole.
This snake is very variable in colour ranging from black and white
to red, yellow and brown, even at the same location.
The slatey-grey snake (Stegonotus cucullatus) is
rather unusual for a colubrid in that it is most often found on the
ground, where it searches for frogs and small mammals. It is a
plain dark grey or brown above with a pale white or yellow belly.
Particularly active after rain, it is found near water and often
near houses, moving around at night. This snake is not
venomous.
