From Peterson's "Guide" and Carson's "Silent Spring" a movement was born: environmentalism. It grew out of a new set of relationships between Homo sapiens and nature. Peterson invited the public to care enough about birds to identify them and, by extension, to identify with them. Carson showed that in caring about the fate of another species we were implicitly protecting our own fate as a species. The "Life List" that is kept by most birders acquired a double meaning: It names every live species seen in a person's lifetime.
Too bad. Environmentalism is, in my view, distinctly inferior to old-time conservationism. I know my birds pretty well, from having grown up watching them in the woods around our house and at our feeder. More encounter than course work. I find those who have take-up birding late in life somewhat off-putting, the way cradle Catholics sometimes find converts. Seeing birds is something I prefer to do on my own, never in a group.