I'll help you understand. Hunting is actually a key part of animal conservation efforts. Hunting licenses are issued primarily for population control. An overpopulation of prey animals is horrible for the environment, its effects rippling out to the local ecosystem affecting hundreds of species. When prey animals over populate the majority of them die painful deaths to starvation. If you care about the environment, you should see nothing wrong with killing prey animals like deer. Their population has to be kept in check for the ecosystem to thrive. Near urban areas there are not enough predators to properly reach balance with these prey animals so humans have to step in.