Module6 Section I Introduction Reading —Pre-reading.ppt

Module 6 Animals in Danger SectionⅠ Introduction Reading —Pre-reading Step 4 Step 3 Step 2 Step 1 ?1.Why would the coal miners take a bright yellow canary down into the mines with them about 100 years ago？ 2.According to the passage， what factors make the habitats (栖息地) for birds smaller and smaller？ About 100 years ago， coal miners would take a bright yellow canary (金丝雀)down into the mines with them. The miners wanted to hear the birds sweet song， but not for the reason you might think. As long as the canary sang， the miners knew the air in the mine was clean and safe. If the canary got sick， they knew it was time to go. The expression“a canary in a coal mine” came to mean a warning device. But with global warming， the canary isnt a canary at all. Its a purple finch. 　　As temperature across the United States has gotten warmer， the purple finch has been spending its winters more than 400 miles farther north than before. A National Audubon Society study published last month found that more than half of 305bird species in North America，including robins， gulls， chickadees and owls， are spending the winter about 35 miles farther north than they did 40 years ago. Birds move for many reasons： They get chased away by more buildings and fewer trees， or they go in search of neighborhoods with backyard feeders. But researchers say the only explanation for why so many birds over such a broad area are wintering in more northern locales is global warming. Over the 40 years covered by the study， the average January temperature in the United States climbed by about five degrees. That warming was most noticeable in northern states， which have already recorded more southern birds. “This is as close as science at this scale gets to proof，”said Greg Butcher， the studys lead scientist. “It is not what each of these individual birds did. It is the wide diversity of birds that suggests it has somet