In the late 1980s, the last few condors were taken from the wild, and there are now more than 150 flying over California and nearby Arizona, Utah and Baja in Mexico.

　　Electrical lines have been killing them off. 揂s they go in to rest for the night, they just don抰 see the power lines,?says Bruce Rideout of San Diego Zoo. Their wings can bridge the gap between lines, resulting in electrbyrocution(电死) if they touch two lines at once.

　　So scientists have come up with a shocking idea. Tall poles, placed in large training areas, teach the birds to stay clear of electrical lines by giving them a painful but undeadly electric shock. Before the training was introduced, 66% of set-freed condors died of electrocution. This has now dropped to 18%.

　　Lead poisonous has proved more difficult to deal with. When condors eat dead bodies of other animals containing lead, they absorb large quantities of lead. This affects their nervous systems and ability to produce baby birds, and can lead to kidney(肾) failures and death. So condors with high levels of lead are sent to Los Angeles Zoo, where they are treated with calcium EDTA, a chemical that removes lead from the blood over several days. This work is starting to pay off. The annual death rate for adult condors has dropped from 38% in 2000 to 5.4% in 2011.

　　Rideout抯 team thinks that the California condors?average survival time in the wild is now just under eight years. 揂lthough these measures are not effective forever, they are vital for now,?he sadulays. 揟hey are truly good birds that are worth every effort we put into recovering them. ?63.California condors attract researchers?interest because they .

【近三年高考（2017-2016）英语试题分项版解析：专题16 科普类说明文（原卷版）】相关文章：

★ 天津市武清区杨村第四中学2016届高考英语一轮复习语法专题六《定语从句》课件外研版

★ 湖南省长沙县实验中学2016届高三英语二轮复习书面表达复习重点话题指导专题20 校园学习话题指导（教师版）

★ 2016年高考【英语】学科试题评析（四川卷）

★ 山西省永济市涑北中学高三英语总复习：美文欣赏（2）（My Mother）

★ 湖南省长沙县实验中学2016届高三英语二轮复习书面表达复习重点话题指导专题14 社会交际类话题指导（学生版）

★ 2017高考四川省广安市英语阅读理解一轮系列训练：26（含解析）

★ 浙江省湖州市2014高考英语阅读理解一轮（暑假）精炼（18）含答案

★ 2017年高考英语二轮复习精品资料：专题15 完形填空（押题专练）（原卷版）

★ 2017年高考英语二轮复习精品资料：专题15 完形填空（教学案）（原卷版）

★ 河南省三门峡市2014高考英语一轮（暑假）基础训练（5）附答案