VOA慢速英语 美国发现两种最古老的珊瑚新品种

　　VOICE ONE:

　　In addition to loss of habitat, birds face many other man-made threats. The report says up to one billion birds die each year from flying into objects like power lines, windows and tall buildings.

　　Environmentalists are studying ways to reduce this number, but these efforts are only beginning.

　　Climate change is one of the least understood threats to birds. The report says temperatures are estimated to increase by several degrees Celsius in the next one hundred years. And sea levels could rise by one half meter.

　　Already, rising temperatures have had an effect on migratory birds. Studies show that some American Robins are appearing in their nesting areas two weeks earlier than thirty years ago. Other birds, like the red-winged blackbirds and eastern bluebirds, are laying eggs earlier because of warmer temperatures. The fear is that, as birds move to nesting areas earlier, they will arrive before food is available.

　　VOICE TWO:

　　Birds native to one state are of special concern to wildlife experts. More than one third of all threatened or endangered bird species in America live on the Hawaiian Islands. Each island is home to a rich collection of animal and plant life. One hundred thirteen bird species are found nowhere else.