Answer:
Space, Food, Water, Breeding Mates
Step-by-step explanation:
Animals need space to grow and raise their young ones, and they are losing their land to people.
They limited to food as some species and plants die off, or decrease.
All animals need water and they sometimes can't aways have it because of possible droughts.
As animal species decrease, their are less mates for Breeding, which would cause the population to decrease.