Because there are not many natural predators, populations can sometimes grow too large for their environments and deer can starve to death. In rural areas, hunters help control deer populations but in suburban and urban areas hunting is often not allowed and deer populations can grow out of control. Other things can change deer populations. Disease and parasites like lice, mites, and roundworms can weaken or kill deer. Young deer and old deer often get sick and die, especially in the winter.
Winter is a dangerous time for deer.
Their long narrow legs and pointed hooves make it hard for them to move around in the snow and ice and it is easier for predators like dogs to catch them. Deer and people are living closer to each other because of human development and growth in deer and human populations. Because humans and deer often share a habitat, there can be problems for both of them. When a deer's habitat becomes smaller because of human development, deer will often eat food from peoples gardens. Deer need to cross roads to look for food and water and are sometimes struck by cars.