Many ornithologists have noticed a disturbing trend in recent years. Namely, many species of birds are disappearing. In fact, over the past two decades, over 100 species of birds have disappeared while another 1,200 are endangered. The evidence points towards humans as the reason why birds are slowly but surely being eradicated.Humans are expanding the urban areas where they mostly live, so they start encroaching on birds- and other creatures - natural habitats. Almost half the worlds population lives in urban centers of some sort, and green areas are low on the priority list in most places. Coupled with this urban centers of some sort, and green areas are low on the priority list in most places. Coupled with this urban sprawal are the increased amounts of pollution being produced in the cities. These factors are combining to take away the birds habitats and to contaminate the places where they live.As Earths population grows, there is an ever- increasing demand for food, so many lands are being cleared to make farmland to produce this food. Large tracts of forested areas are being cleared to grow crops on, and there is little thought given to the fate of the birds who nest in these forests. Approximately 50,000 to 170,000 square kilometres of forest are cut down yearly, which is putting many species of birds at risks.Farmers often rely upon chemical insecticides to eliminate any insect infestations. These chemicals are also killing many birds as well as other animals. This is one reason the insecticide DDT has been banned for almost forty years in the United States. It was simply killing too many birds, particularly the bald eagle. Unfortunately, in the rest of the world, DDT and other powerful chemicals are still being used on farms and are therefore killing large number of birds
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