Lucas & Frost 1903
Spencer's goanna, plain goanna
Spencer's goanna is the least known of the large Auscralian
monitor lizards. It appears to live only in grass lands on the
clay plains of eastern Northern Territory and north-western
Queensland (Cogger 1993). They usually reach lengths of
100cm TL (Schmida 1985) with a maximum of about
125cm TL. The tail is only slightly longer than the head and
body (103-107% of SVL). This is a heavily built species that often has a very thick tail base
and attains weights of over 2.25kg (Mertens 1958; Bustard 1970). Hatchlings measure about
22cm TL, 13cm SVL (Peters 1986). The short toeS are equipped with long powerful claws
which enable these lizards to burrow through clay. They are said to be most active between
August and October (Schmida 1985). Pengilley (1981) found large numbers of females
looking for nest sites among piles of red soil dumped at the side of a road in late September
and early October. A wild caught female laid eggs at the beginning of November. Clutch size
is large, with up to 31 eggs. each measuring about 5 × 3.5cm, recorded from large females
Spencer's· goannas usually shelter in burrows or large cracks in the clay and often inhabit
areas devoid of trees (Stammer 1970; Swanson 1976). In captivity they are able to climb
quite well (McKeown pers comm.) and so may explore trees where they are present. The
adult females examined by Pengilley (1981) had eaten mammals, large snakes. agamids.
mammals and insects (mainly orthopterans) . A specimen examined by Stammer (1970)
contained large numbers of beetles. The stout bodies suggest that they are inactive
throughout the winter, but there are no direct observations to substantiate this. Bipedal ritual
combat in this species was first recorded by Waite ( 1929), who mistook them for perenties .
(Horn 1981). A burrow, probably intended as a nest is depicted by Pengilley (1981).
There are few references to the care of this species in captivity (e.g. Peters 1969a,c, 1970a,
1971, 1986). They require a spacious terrarium which provides plenty of opportunities to dig
and would probably benefit from a seasonal reduction in activity. Eggs laid by a wild caught
female hatched after 133-140 days at 29°C (Peters 1986). juveniles are much more colourful
than the adults, with bright yellow bands over a glossy brown back. They double in size
within six weeks. In captivity, Spencer's goannas are said to be somewhat nervous but
tolerant They can live for at least 15 years (Snider & Bowler 1992).