It is simple biology and ecology. The fact of the matter is that deer are a prey species and, as such, predators (single-celled, 2-legged, or 4-pawed) have always and will always kill them. It's the very definition of prey — an organism that is killed and eaten by another organism (i.e. predator).

Predation is defined as the ecological process through which one animal (or creature) kills and feeds on another animal (or an organism). A "predator" is an animal that kills another animal to feed on. Examples are wolves hunting deer or moose, owls hunting mice, and lions hunting other animals.

Predation Examples in the Mammal World A pride of lions attacking a larger animal, such as an elephant or wildebeest. Dolphins chasing and eating fish. Orca whales hunting seals, sharks, and penguins. House cats killing mice, birds, and other small animals. A pack of coyotes chasing and killing rabbits.

The balance of nature, as a theory, has been largely discredited by scientists working in ecology, as it has been found that constant disturbances leading to chaotic and dynamic changes are the norm in nature. During the later half of the 20th century, it was superseded by catastrophe theory and chaos theory.

Death by predators is the preferred method over death by starvation. When a population is starving, the members of that population will become malnourished and weak. This will lead to an unhealthy population that is more susceptible to disease.

Predation and Deer Population. Predators kill white-tailed deer. Field studies from across the United States, including Pennsylvania, show that predators - notably coyotes, bears, and bobcats - prey on white-tailed deer. Predation is a natural form of mortality for white-tailed deer.

Examples include: Locust insects harm the seed crop by predating on it. Lion(predator) eating a deer(prey). Snake(predator) killing rat(prey).