Phenology Calendar — What Happens When in Nature | Bill Felker

The timing of nature’s recurring events — a practical guide to what to look for and when to look for it.

Phenology is the study of what happens when in nature — the timing of recurring biological and atmospheric events that mark the true calendar of the natural world. Bill Felker has been building his phenology calendar from Yellow Springs, Ohio since the late 1970s.

His records include wildflower bloom times, insect emergence dates, bird arrival and departure windows, the ripening of wild fruits, first frost, last freeze, and hundreds of other natural events that repeat with remarkable consistency from year to year.

Wildflowers
Bloom times from January hepaticas to December seedheads
Birds
Arrival and departure windows for migratory species
Insects
Emergence dates for fireflies, katydids, monarchs and more
Weather
Frost dates, cold fronts and seasonal pressure patterns

Bill’s contribution is forty years of firsthand observation from a single carefully watched landscape — a record of natural timing that is both scientifically useful and beautifully written. If you want to know when the first fireflies will appear, when the goldenrod peaks, or when to expect the last killing frost, this is the place to start.