导读：美国政府发出悬赏，谁要是找到一只旅鸽，可以得到奖金1500美元。然而，直到今天，没有一个人得到这笔赏钱。
对应考题：2010.01.15北美托福阅读题
Passenger Pigeon 旅鸽
Passenger pigeons became extinct in the early 20th century
North American passenger pigeons were once known as one of the spectacles of the continent. They flew in flocks that were billions strong, clouding the skies like locusts during their migration season. But massive killing campaigns wiped out the birds quickly; in a few centuries, the pigeon population that once numbered about five billion was completely destroyed.
Early flocks of passenger pigeons were sometimes more than a mile wide, taking hours to pass overhead. They were a huge threat to farmers, and their agricultural impact is part of what prompted the frenzied extermination of the species. Another reason they were killed in droves was for their cheap meat, which was sold to servants and slaves, two birds for a penny. Thousands of birds were killed at one time using poison, fire, and guns. The last flock of passenger pigeons, which numbered about 250,000 birds, was killed off in a matter of a few days in 1896; the killers had the distinct purpose of bringing the species to extinction. A few remaining birds were sighted through the early 20th century, but the species had entirely died out by 1910.
One good thing did come of the slaughter of passenger pigeons; their extinction led to an interest in the conservation movement. In part because of the passenger pigeon’s extinction, new legislation has helped other species survive in the United States.
中文背景：
旅鸽,顾名思义,是一种特别喜欢旅行的鸽子。是一种拥有修长尾羽的小型蓝色鸽鸠类。17世纪的北美拥有超大型的旅鸽种群。据估计，当时有多达五十亿只的旅鸽生活在如今隶属美国的广大区域内，而这仅仅是其种群总数的三分之一左右。早期的探险者曾被它们遮天蔽日的迁徙群体所震撼，而这种震撼要经过三四个小时才慢慢消失在天际。但是，由于欧洲移民的过量捕食，这种拥有庞大家族的美丽鸟类，在繁衍生息了25万年后，于20世纪初从这个星球上彻底的消失了。
