In the late April 2014, a violent storm swept through the southern Unite States, 【小题1】 (destroy) more than $1billion in property and killing 35 people. But a group of migratory birds in eastern Tennessee sensed the oncoming mess and left long before the first clouds arrived. A year earlier, the team had tagged golden-winged warblers(莺) with leg trackers 【小题2】 (study ) their annual migrations to South America. Two days before the storms 【小题3】 (strike), five golden-winged warblers sipped away traveling nearly 700 kilometers south to the Florida coast.

It is the first time that the birds which normally migrate with the seasons 【小题4】 ( observe） to slip away when a big storm hits. The researchers suspect this 【小题5】 (behave ) occurs only when the threat of injury outweighs the energy costs of a long trip. But nobody knows 【小题6】the birds guessed the storm's severity and left so soon. 【小题7】 (Puzzle)by it, the scientists initially reasoned that delicate changes in weather-atmospheric pressure, temperature, wind speed, cloud cover, or rainfall signaled the upcoming disaster. Yet when they checked weather records, none of these factors waved 【小题8】 (significant) before the storm. Instead, the team assumes that the approaching storms created 【小题9】disorder of infrasounds --- low-frequency sound waves that bird can hear 【小题10】humans can't.