The author of the reading passage argues that human population growth and the corresponding increase agriculture and pesticide use have caused harm to wildlife in the US, especially bird. But the speaker in the lecture thinks the arguments the author uses are unconvincing, she argues the author as the following points.
First, the speaker does not agree with the point that the human populations and settlements continue to expand, and birds' natural habitats will disappear. She says the human settlements indeed decrease some type of birds' habitat, but they also provide better and large habitats for other types. What is more, some species even grow better in cities, for example, we can see hooks in big cities, which prey on the increase number of rodents.
Second, the speaker thinks the growth of agriculture will not increase and further destruct bird habitats so soon as the author claims. On the contrary, as the development of technology, the agriculture land in the US is less every year. And we have developed crops which need less land and can feed more people. So there is no need to destroy bird habitat any more.
Third, the speaker argues that because we have been aware of the harm of traditional chemical pesticide, we make 2 important changes. First, develop new type of pesticide which is less poisonous. Second and more important thing is we are working genetically pest-resistant crop, which are resistant to pest while no harm to birds. So the harm of chemical pesticide is declined as well.