VANISHING VOICES:As the continent's grasslands disappear, the songs of the birds that depend on them are also fading away

摘要

Casey, Northern Rockies coordinator for the American Bird Conservancy. "And that extraordinary habitat loss has taken its toll on birds." At the time of European settlement, approximately 360 million acres of shortgrass, tallgrass and mixed-grass prairie cloaked the mid-continent from Canada to Mexico, stretching green and gold from the foot of the Rockies to the great deciduous forests of the East. Today, these native grasslands have been plowed and paved and drained into a mere shadow of their former selves: Only about 70 million acres are left. In Iowa, a meager 30,000 acres of native prairie remains of the 23 million acres found in the state in 1780. Half the native prairie in North and South Dakota has vanished. All told, only 3 percent of thenation's original 167 million acres of tallgrass prairie remain intact.