This species of deer actually

The tools still said "old fox cat", but it turns out that old deer also become . elves.

As one of the largest species in the deer family, North American deer have almost no natural competitors. Their most dangerous enemies to date are humans.

People with weapons and tactics have become the top creatures of the food chain, even threatening the existence of many other organisms. However, according to a new study, North American deer - more specifically the female deer - live longer, they will almost not fear any threat from humans.

The older the deer, the better.

Outside nature, if you see an old deer, it is more likely to be a female deer, because the male deer rarely live for more than 5 years because the hunted person takes the horn. And the deer, the longer they live, the more they know how to hide and distinguish each weapon that hunters use. And if you live for 10 years, it can be said that human hunters don't dream to touch them.

The researchers said they wanted to understand why many deer could live for so long. There are two hypotheses given: hunters' selection - mainly hunting strong deer and deer; or due to adaptability after many years of being hunted.

After a few years of observing a herd of deer in Canada, they came to a conclusion. In it, along with the continuous hunting pressure from hunters, they also learned the appropriate moves to avoid danger.

Suddenly, the hunter shadow is far away, they will be gone.

The longer they live, the more deer will realize that the less they move, the more likely they are to be attacked and discovered. They also form some habits that match the risk of each area they have traveled.

Remarkably, they even distinguish the human weapon used - including guns and bows. For example, at the time when hunters often use bows - weapons that require hunters to come close, the deer will tend to be around the rugged terrain. As for guns, they will avoid highways, hide in remote areas, are difficult to access.

But not only based on time, experts say they also rely on hunter's behavior to guess the weapon they use. For example, when using a gun, the hunter tends to slow down on the road to observe, and it seems the deer have learned it.

The study is published in the scientific journal PLOS ONE.