Increased population in United States causes birds population to decrease.

The article poses three factors related to human civilization in United States and delineates how they have been making a great number of birds on the verge of drastic reduction. By way of contrast, the professor considers them unpersuasive for the sake of the birds drop and repudiates them.

The author first claims that growing trend of human population makes people devastate natural habitats of birds so that they can attribute those lands to their construction projects and subsequently loss of habitats leads to this decline. However, the lecturer explains although urban growth restricts some types of birds' habitats, it provides better and larger environments for other kinds of birds as we can observe different species like hawks, seagulls and pigeons in the cities.

Another consequence of increased population is the adequate amount of food, basically crops, which needs more and more fields for planting and harvesting. By the same token, having intensive agriculture requires destroying natural habitats and shifting them to farms which causes birds to diminish. Conversely, the professor discusses new kinds of crops that are more productive as they can produce more food per unit of land and they have been being used in United State so as to they destroy less and less natural habitats like the time when they used wilderness areas for agriculture.

At last, the reading passage posits that the more people extend agriculture, the more pesticides will be used in order that they can control pests. Subsequently, these chemical pesticides penetrate to the water and food chain inadvertently and not only do the birds die due to both drinking and eating infected water and insects, but also would be hurt as they cannot breed properly. Despite the fact that the lecturer believes that traditional pesticides were destructive to birds, she declares that modern pesticides are devised with two principal differences that we should not generalize its lethal effects to the future anymore. First, they are much less toxic and poisonous; second, and perhaps more significant, they are genetically designed to make crops pest-resistant so that become unattractive to pests and they are not harmful to birds as well.