What about animals that came across on land bridges or colonised millions of years ago but arrived by drifting on ocean currents etc, and have become an integral part of our ecosystems. I give the native Boab, Adansonia gregorii as an example, as it is sufficiently different from any of the Madagascar species or the African species. It has also evolved to suit our conditions (the shells of the pods are much more fragile as there are no native monkeys, like those which crack the hard cases of African species to reach the pith). These are unquestionably native. A native plant is any species which has not been introduced by man. Thus the peregrine falcon is native to both America and Australia, but the tamarind, introduced by Macassan fishermen to the top end before the arrival of white man, is not.