To begin with, human activity destroys the wilderness areas and significantly reduce biodiversity of the planet. Constantly growing population makes people look for new places to grow crops or ranch cattle; unfortunately, this often means that people sacrifice wilderness areas in order to satisfy their growing needs. Preparing the land for farming, people cut trees and destroy vegetation; as a result, natural habitat of animals is affected. Many species of birds and mammals face extinction because of people's encroachment, not to mention hunting activities. Thus, the development of wilderness areas results in decrease in biodiversity of birds, mammals, and fish.