Deer are preyed upon by a variety of predators, including wolves, coyotes, bears, mountain lions, and bobcats. Hunting by humans is also a significant cause of deer mortality.
Disease
Deer are susceptible to a variety of diseases, including chronic wasting disease (CWD), epizootic hemorrhagic disease (EHD), and blue tongue disease. These diseases can cause high levels of mortality in deer populations.
Accidents
Deer are often killed in accidents, such as collisions with vehicles or trains. They may also drown in bodies of water or become trapped in fences or other structures.
Winterkill
During severe winters, deer may die from starvation or exposure. This is especially true for deer that are in poor condition or that have not been able to store up enough body fat for the winter.
Starvation: During harsh winter months, when food is scarce, deer may struggle to find enough to eat. This can lead to malnutrition and eventually starvation.
Old age: Like all living creatures, deer have a natural lifespan. The average lifespan of a white-tailed deer is around 10-12 years, although some individuals can live for longer. As deer age, their bodies become less efficient at functioning, and they may become more susceptible to disease and injury.