What could cause a population of deer to decrease?

One thing that would cause the population of deer to decrease is the overpopulation of coyotes, bears, and wolves. Wolves and bears eat small rodents, this means that if there is a lot of rodents wolves and bears would be able to thrive therefore eating deer. Another reason deer populations would decrease is if other consumers eat producers. Deer would have a hard time keeping up as producers would not be able to grow too quickly. The last reason deer populations would decrease would be because of deforestation as humans cut down trees to make paper and other wooden utilities.

I hope I was able to help!