Extinction is actually a normal process in the course of evolution.
Throughout geological time, many more species have become extinct than exist today. These species slowly disappeared because of climatic changes and the inability to adapt to such conditions as competition and predation. Since the 1600s the process of extinction has accelerated rapidly through the impact of both human population growth and technological advances on natural ecosystems. Today the majority of the world's environments are changing faster than the ability of most species to adapt to such changes through natural selection. The primary cause is the destruction of habitat, drainage of wetlands, conversion of shrub lands to grazing lands, cutting and clearing of forests and urbanization and suburbanization.