In sorting through my files of nearly 60 years on ecological phenomena, I came across my graduate school professor’s “Ecological Calendar of the Chicago Area” by Orlando Park (then of the Department of Zoology, Northwestern University), a copy of which I obtained in ca 1961. To my knowledge, this calendar was never published, but was used as a guide in field biology classes. This phenological calendar of mostly animals, and mainly invertebrates, covers the time period 1922-1937. Now nearly 100 years later, with the growing concerns about climate change and the keen interest in the effects of global warming upon ecological systems, I thought that it would be of value to the scientific community to have a record of how the timing of these ecological phenomena might have changed in the ensuing years. Incidentally, I found it fascinating to reminisce over the classic study areas of early “Chicago School” of ecologists and the locations of visits by generations of university field biology classes. The manuscript is submitted, without editing, in its original format.