I am currently reading Scott Weidensaul's Return to Wild America. This book gives the reader a history of American conservation challenges over the past half-century. The author retraces Fischer and Peterson's route and discusses fifty years of environmental change and growing public support for environmental causes. Despite urban sprawl, not everything has gone downhill since the 1950s. Since then, many of the hallmark environmental laws have been passed and many acres have been preserved for wildlife. The result is that bird populations have changed, often for the worse, but occasionally for the better. A small drawback is that Fisher, Peteron, and Weidensaul all avoided the upper Midwest.
I picked up Return to Wild Ameica because I enjoyed Weidensaul's Of a Feather, a well-written and entertaining history of North American birding. I can recommend this book to anyone wishing to learn about the history of ornithology and birding in the United States.