SURVIVAL STRATEGIES OF THE ECHIDNA TACHYGLOSSUS-ACULEATUS SHAW 1792 (MONOTREMATA, TACHYGLOSSIDAE)

The area occupied by the Western Australian wheatbelt has experienced extensive land clearing for agriculture between 1900 and 1970. In many areas > 90% of the original vegetation has been cleared, and exotic predators (fox and cat) are common. Of the 56 mammal species recorded for the region since agricultural settlement, 25% have become extinct and a further 21% have declined in range. Yet not all species have been equally affected. The echidna Tachyglossus aculeatus acanthion, a termite- and ant-eating specialist, remains ubiquitous and its populations are stable. It is successful because (a) it is not restricted by habitat; (b) it specializes on an abundant and reliable food source for which there is no apparent competition; (c) it is metabolically capable of tolerating low energy conditions, such as drought- or fire-induced food shortages; (d) its shelter requirements are independent of vegetation; (e) predation on adult animals is minimal; and (f) it can survive outside nature reserves, and is capable of dispersing to distant remnants. Morphological and physiological adaptations to myrmecophagy (termite- and ant-eating) now enable Tachyglossus to cope with exotic predators and the loss of fragmentation of habitat. These adaptations are likely to benefit other mammalian myrmecophages living in similar environments. The native numbat Myrmecobius fasciatus is an exception. It has declined to < 10% of its former range because it lacks an effective defence against exotic predators, and is today restricted to habitats where log shelters provide a measure of protection from fox and feral cat.