We often think of a threatened species as rare, such as the Javan rhinoceros with fewer than 100 individuals left in the world.
However, there are many factors than can influence the risk of extinction of a species and thus its conservation status. These factors include:
- the number of individuals remaining
- overall increase or decrease in the population over time
- breeding success rates
- change in geographic distribution
- known threats.
In the case of the grey-headed flying-fox, its conservation status is based not on the numbers of animals in existence, but on the rapid rate of decline in numbers over a relatively short period.
To demonstrate, imagine that the number of people in Australia suddenly dropped from 23 million in 2015 to just 13 million in 2025. There would still be millions of people in Australia, but the rate of decline would be cause for great concern. Prompt action would be required to halt any further decline.