The sudden removal of ANY species from an established ecosystem causes an instability which affects the whole food chain. Native eagles, for instance, are now dependent on the non-native rabbit as a major source of food. Now that Calisivirus has killed millions of rabbits, both the Wedgetailed and the Little Eagle are threatened, because this important food source has suddenly disappeared.

Botanist Tim Lowe, in his paper Attack of the Savage Honey-Eaters, showed that the loss of species of native birds in Brisbane suburbs has been caused by gardeners destroying vast tracts of the introduced 'pest' Lantana, unaware that native birds now prefer Lantana as a habitat. Moreover the native banksias with which gardeners replaced the Lantana, attracted noisy mynas - a native bird - but a large and aggressive one and this bird chased away the remnants of the little birds and they were seen no more.