Urban vs Rural birds

The article that I read had an abstract section that gives the reader a little background information on what it is about. The main point of the article was to figure out how urban birds tend to produce smaller and lighter offspring than rural birds. The introduction section talks about how human populations are growing and migrate to urban areas and how this change is having an impact on urban birds. I learn that “in general, life-history theory predicts that adult birds under threat of predation will reduce offspring feeding rates and consequently have reduced nestling growth rates”. I was surprised to find out that urban birds tend to reproduce less because of fear of predation, why not rural birds? because rural birds would have a greater chance of eating by their preys than urban birds.