Birding is a popular pastime that naturally leads to an interest in bird identification.
观鸟是一项很流行的休闲活动，自然而然地会使你对鸟类鉴别产生乐趣。
Physical characteristics that are important in bird identification include colors, markings, and bill or beak.
羽色、特殊标记以及鸟喙形状等特征在鸟类识别中有很大作用。
The researchers linked the rate of evolution in the parasites to the rate of evolution in bird hosts in the West Indies.
研究者将寄生虫的进化率和西印度群岛的禽类宿主的进化率联系起来。
Three of the cases they studied found that the rise of West Nile virus in the U.S. corresponded to decreases in bird population density.
他们在研究过的三个案例中发现西尼罗河热在美国的的流行与鸟类种群密度的下降相关。
The findings showed that over 20 years there was a 71 percent drop in native butterfly populations and a 54 percent drop in bird populations.
结果发现，20年来本地蝴蝶的数量下降了71%、鸟的数量下降了54%。
Avian influenza has caused widespread epidemics in bird population in many parts of the world.
禽流感已逐渐演变成在全球各地禽鸟中散播的疫症。
Another reason for the increase in bird strikes is the growing popularity of air travel in the United States.
另一个导致鸟撞事件增加的原因是美国空中旅行的普及程度的增加。
This activity provides fundamentals of bird-watching and is suitable for those who have interests in bird-watching.
本活动提供基础的观鸟知识，适合任何对观鸟有兴趣的人士参与。
With the going deep in understanding of Ecology, more and more eco-methods were emerged in bird strike control and prevention.
随着对生态学的认识逐步加深，目前国际上出现了越来越多的以生态学手段防治机场周围鸟害的方法。
The proportion of the avian distribution groups in bird community was changeable as a result of the variation of the habitat structure.
各种鸟类分布群在鸟类群落内的比例随栖息地结构的变化而改变。
Despite efforts to vaccinate and control the population of infected birds, H5N1 is considered firmly entrenched in bird populations across large parts of Asia.
尽管人们努力接种疫苗和控制已感染的禽鸟数量，但H5N1病毒仍顽强地存于亚洲大部分地区禽鸟群内。
So pesticides have significantly contributed to declines in bird population and because there will continue to be a need to control agricultural pests in the future this decline will continue.
所以，杀虫剂会对鸟类的数量有非常严重的影响。同时，因为即便是在将来，还是需要杀虫剂来控制农业害虫，所以，鸟类数量减少的趋势难以改变。
So, pesticides have significantly contributed to declines in bird population, and because there will continue to be a need to control agricultural pests in the future, this decline will continue.
所以，杀虫剂会对鸟类的数量有非常严重的影响。同时，因为即便是在将来，还是需要杀虫剂来控制农业害虫，所以，鸟类数量减少的趋势难以改变。
So, pesticides have significantly contributed to declines in bird population, and because there will continue to be a need to control agricultural pests in the future, this decline will continue.
所以，杀虫剂会对鸟类的数量有非常严重的影响。同时，因为即便是在将来，还是需要杀虫剂来控制农业害虫，所以，鸟类数量减少的趋势难以改变。
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