A now extinct breed of North American pigeon. Once extraordinarily common, it was hunted to extinction in the 19th century.
Passenger Pigeon Term Timeline in A Sand County Almanac
The timeline below shows where the term Passenger Pigeon appears in A Sand County Almanac. The colored dots and icons indicate which themes are associated with that appearance.
Part II: Wisconsin
Part III: Natural History
...Instead, he is impressed by a chemist who taught himself about the history of the passenger pigeon by extensively reading archival material about it, and an Ohio housewife who obsessively observed and... (full context)