From Tropical Topics newsletter, No. 78 June 2003,
produced by Stella Martin at the Queensland Environmental
Protection Agency. Download the PDF to read the whole issue.
Acknowledgements to Russell Best, Queensland Parks and Wildlife
Service and Tony Griffiths, Key Centre for Tropical Wildlife,
Charles Darwin University.
Geckos in the tropics | Family
Gekkonidae | Diplodactylus genus | Spiny-tailed gecko |
Bynoe’s gecko |
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Knobtail gecko found in north east Queesland in the Charters Towers
area. Photo: Leonie Valentine
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Geckos are among the most familiar of tropical animals, living
in our houses, scuttling around our ceilings, swarming around our
outside lights to pounce on dazzled insects and conducting their
affairs behind our picture frames. Several species of geckos
qualify as ‘house’ geckos, having adopted humans as
co-habiters. Gehyra dubia is found widely in Queensland and
northern New South Wales. Varying in colour from pale pinkish to
brown with darker markings, it can also be found in the wild on
trees and in rock crevices.
Another species, Hemidactylus frenatus , is an import
from Asia which has hitched a lift with travelling humans. It is
now found at the tip of Cape York Peninsula, around Cairns and in
the Northern Territory where it is spreading from Darwin to
settlements along the road south towards Alice Springs. It seems to
be dependent on human habitation. This gecko can change colour,
becoming pale at night and dark during the day. Although similar in
appearance to Gehyra dubia, it can be distinguished by its
slightly spiny tail. It also has a distinctive loud scolding call;
native house geckos make only a soft chattering call.
The nocturnal lifestyle of geckos prevents them from basking in
the sun as most lizards do to raise their body temperatures.
Instead, they choose daytime retreats which are warmed by the sun,
particularly in the afternoon, so that they are full of energy by
sunset. Competition for suitable spots can be fierce, leading to
fights between opponents during which they grasp each others’
tails in their mouths.
There are more than 90 gecko species in Australia, most of them
under 20 cm in total length. These are nocturnal lizards although
they may be active in dark places during the day. They feed only on
prey which moves, such as insects and smaller geckos. A
gecko’s eyes are permanently covered with a transparent
eyelid, perhaps to reduce evaporation. Unable to clean its eyes
with tears, the gecko licks them with its tongue. Some gecko
species are parthenogenic, meaning that the females can produce
offspring without male input.
Over 30 of the gecko species found in Australia belong to the
Diplodactylus genus. The fat-tailed diplodactylus
(Diplodactylus conspicillatus) is found only on the ground
in stony and grassy areas across much of the top of Australia, its
colour varying to match the habitat in which it lives. About 10cm
in total length, it has a bulbous tail which acts as a fat storage
organ, and feeds on termites and other insects. The fat-tailed
diplodactylus spends its days in underground holes, such as
abandoned burrows of trap-door spiders, blocking the entrance with
its fat tail to keep out predators and keep in moisture. It is
sometimes called the burrow-plug gecko. Most adults have lost their
original tails which are replaced with more rounded ones which make
even better burrow-plugs.
The spiny-tailed gecko is found in woodlands and grasslands,
westwards from western Queensland, living in trees or other
vegetation. It is also frequently seen on roads. This is one of 10
‘tail-squirting’ species. It can eject an offensive and
sticky liquid from the spines of its tail. By lifting its tail it
can aim the fluid accurately up to a distance of 30 cm. This gecko
is also particularly good at changing colour from dark to very
pale.
Bynoe's gecko is very common throughout most of the Australian
mainland. Also known as the prickly gecko, because of its bumpy
skin, it thrives in all types of habitat from forests and woodlands
to arid areas. It shelters in crevices, under logs and in rocks,
but at night searches open ground for insects — and other
geckos. These geckos sometimes lay eggs in communal nests which may
contain up to 150 eggs .
