Australian Deserts by Unknown

Author:Unknown
Language: eng
Format: epub
ISBN: 9781486306015
Publisher: CSIRO Publishing
Published: 2021-11-24T00:00:00+00:00

Sand goannas occur in almost every habitat throughout arid Australia.

Goannas lay their eggs at the end of summer, if conditions have allowed the female to harvest enough energy; most females probably lay only every second year. The eggs of large goannas hatch at the beginning of the next summer, 8 months or so later. The need to protect eggs for such an extended period has led to extraordinary nesting burrows, as revealed by studies of sand goannas and ­yellow-spotted goannas in the Pilbara (Fig. 7.1). Each species nests in communal warrens, at sites chosen, presumably, for the suitability of soil. The warrens appear to be used for many years, for excavation has revealed old nesting chambers with hatched eggshells, as many as 100 burrows coiling downwards side by side, of which perhaps 30 are active at a time. The nesting burrow begins with a straight sloping section, followed by a helix of about seven tight turns that terminates in an egg chamber. The chambers of sand goannas are found at astonishing depths of 3 metres, and those of yellow-spotted goannas at 2.5 metres. Mothers excavate most of the burrow without removing the soil, and ‘swim’ back out of it after laying six or so eggs. The hatchlings emerge months later, apparently ignoring their mother’s helix and digging their own linear emergence burrows.31

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