Birds occupy every available niche; thus, of the world's approximately 10,000 species of birds, around 4,500 are found in the Americas with many discovered each year. While the majority of species are found in the tropics, the enormous diversity of birds in the Americas includes species adapted to the driest deserts, highest sierras and even the cold regimes of Patagonia.
Though American birds adapt to these different circumstances, threats are definitely reality. American birds are threatened by air pollution and human activities such as traveling and hunting.