For a species to be considered endangered it must meet a set of criteria. Species are ranked based on how endangered they are.

Ranking	Population Reduction Rate	Population Size
Vulnerable	30-50%	less than 10,000
Endangered	50-70%	less than 500
Critically Endangered	80-90%	less than 250
Extinct	No remaining individuals in species

1. Habitat loss and fragmentation
2. Invasive and non-native species
3. Population growth
4. Pollution
5. Climate change
6. Overexploitation