If the climates are similar there is a much higher risk. If a species has a history of becoming a widespread pest in another country, then the risks are high for it becoming a pest in Australia. These factors that contribute to the establishment success all need further confirmation by rigorous scientific studies. There will always be uncertainty. Development of new behaviour patterns are hard to predict.
Exotic mammals are more often pests than exotic birds.
Some animal families pose a particularly high risk because they contain many species that are agricultural or environmental pests. Particular caution is required when considering the import of new species from these families. Commonwealth of Australia 2000 .