People feel that hunting should be illegal because the more you hunt, the more you can actually make an animal endangered, or even extinct (as in the case of the Tasmanian tiger). Another disadvantage is that it can hurt the ecosystem of the area where you are hunting by removing an animal form it, thus permanently affect that area.
People also feel hunting is cruel if you are doing it for sport. Killing life forms for the enjoyment of it seems a bit morbid.
People that are sensitive to animal rights are usually the ones that state that hunting should be illegal. Many people may be against hunting, but they usually think that hunting should be regulated instead of being illegal.
First: animals that become extinct do so because of a lack of regulations regarding hunting. Contrary to popular believe, legal hunting does not drive animals into extinction. In fact, there are many restrictions that limit how hunters may chase game. Illegal hunting, such as driving deer, or baiting leads to excessive amounts of dead animals. Hunting is allowed in today's society because it keeps the animal populations from becoming too large. If there were no whitetail deer hunters, then the amount of whitetail deer would skyrocket. What's the big deal then? Well, deer interfere too much with civilization. More deer would get killed in traffic accidents, leading to more human deaths. They would begin to invade other areas where humans previously held residence. Basically, they would become a nuisance"like the red squirrel. The difference between a red squirrel and a whitetail deer is their size. Having many red squirrels really does not effect us because they are so small and occupy such little territory. Deer on the other hand, do not have such an inconsequential effect. Besides that, deer would suffer more without hunters. The amount of food available for deer would decrease as the deer population grew. What does that mean? That means that instead of dying by gun, a deer might starve to death over throughout a long and cold winter. Population control is all that deer hunting is.
Second: The majority of hunters do not hunt for the joy of taking life. Personally, I hunt because of the thrill of being in nature. Hunters are more environmentally conscience than non hunters, and we actually care more about wildlife than most people. Hunters aren't killers. To say so is to make an uneducated statement. We hunters hold a deep respect for the animals we hunt. When most hunters make a kill, they do so cleanly, and try to put as little pain upon the animal as possible. We would much rather see a one shot kill than a deer get hit and bleed to death after it runs 6 miles. Watching a deer suffer is the last thing anyone wants, and for that reason, most hunters only take shots they know they can make (of course there are always exceptions). One of the first things that a hunter learns in hunters safety is never to take a shot at a running deer. Taking a shot at one would be unethical and most likely result in suffering on the deer's part.