Now listen to a part of lecture on the topic you just read about.
现在来听一段关于你刚刚读到的话题的演讲。
The passage claims that there will be fewer and fewer birds, but the arguments used to support this claim are unconvincing.
文章声称会有越来越少的鸟类，但是用来支撑这一断言的论据没有说服力。
First, it's true that urban growth has been bad for some types of birds, but urban development actually provides better and larger habitats for other types,
首先，城市扩张确实是对一些种类的鸟有坏处，但是城市发展事实上给别的种类提供了更好更大的栖息处，
so much so that city and suburban dwellers often complain about increased birds populations — seagulls at landfills, pigeons on the streets and so on.
以至于城市和郊区的居民经常抱怨增加的鸟类数量--垃圾填埋场里的海鸥、街上的鸽子等等。
Even birds like hawks and falcons can now be found in cities, where they prey on the increasing populations of pigeons and rodents.
甚至像鹰和隼这样的鸟类现在也能在城市里找到，在这里他们捕食数量越来越多的鸽子和啮齿动物。
So it's not going to be a story of uniform decline of bird populations in the future.
所以这不会是一个鸟类数量在未来统一下降的故事。
Some populations may shrink, but others will grow.
有些种群会缩小，但是其他的会增长。
As for agriculture, it's true that it too will increase in the future, but not in the way assumed by the reading passage.
对农业来讲，它在未来也确实会增加，但是不是以阅读文章中假设的方法。
The truth is, in the United States, less and less land is being used for agriculture every year.
事实是，在美国，每年越来越少的土地被用于农业。
Increases in agricultural production have resulted from and will continue to result from the introduction of new, more productive varieties of crops.
农业产量的增加已经并将继续得益于引进新的更加多产的农作物品种。
These new crops produce more food per unit of land, and as a result, there's no need to destroy wilderness areas.
这些新的农作物每单位的土地能生产更多的食物，所以，没有必要破坏自然保护区。
And third, while it's certainly true that traditional pesticides have been destructive to birds, it's incorrect to project this history into the future.
第三，虽然传统的农药对鸟类有害确实是真的，但是把这个历史投进未来是不对的。
Now that people are aware of the possible consequences of traditional pesticides, two changes have occurred.
现在人们意识到传统的农药可能的后果，两个变化已经出现。
First, new and much less toxic pesticides have been developed, and that's important.
第一，新的、毒性更少的农药已经开发出来，这很重要。
Second, and perhaps more importantly, there is a growing trend to develop more pest resistant crops, crops that are genetically designed to be unattractive to pests.
第二，可能是更重要的，有一个开发更多抗虫农作物的发展趋势，这农作物从基因上设计得对害虫没有吸引力。
Pest resistant crops greatly reduce the need for chemical pesticides. And best of all, pest resistant crops don't harm birds at all.
抗虫农作物大大地减少了化学农药的需求。而且最好的是，抗虫农作物根本不会危害鸟类。