List 4 contributing factors that affect population?

Some environmental factors affecting population growth include:

1) Bacteria and disease For Ex. West Nile

2) Natural disasters For ex. Tsunamis

3) Unbalanced Predator/Prey relationship For Ex. a decline in the fox population will cause in increase in the hare population

Some non-environmental factors affecting population growth:

1) Death

2) Birth

3) Emigration

4) Immigration