Programs
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The Aldo Leopold
Foundation
P.O.Box 77
Baraboo, WI 53913
608.355.0279
608.356.7309 fax
mail@aldoleopold.org
The Study of Phenology
“Many of the events of the annual cycle recur year after year in a regular order. A year-to-year record of this order is a record of the rates at which solar energy flows to and through living things. They are the arteries of the land. By tracing their response to the sun, phenology may eventually shed some light on that ultimate enigma, the land’s inner workings.” –Aldo Leopold, A Phenological Record for Sauk and Dane Counties, Wisconsin, 1935-1945
Phenology is a segment of ecology focusing on the study of periodic plant and animal life-cycle events that are influenced by climate and seasonal change in the environment. Skunks emerging from winter dens, sandhill cranes trumpeting their return, and seeds ripening are all examples of annual phenological events. Phenology is derived from the Greek word phaino meaning to show or appear, indicating its principal concern with the dates of first occurrence of natural events in their annual cycle.
Phenological first began being recorded at the Leopold shack and farm by Aldo Leopold in 1936. Leopold took recordings from 1936-1947 in and around this landscape, which inspired Leopold's seminal work on conservation: A Sand County Almanac.
Nina Leopold Bradley continues to carry on her father’s work today, compiling a robust phenological database spanning from 1974 through the present. She has found that a substantial number of phenological events occur much earlier now than they did during Leopold's lifetime. Several studies have shown a significant trend for an earlier occurrence of spring phenological events suggesting some species are changing behaviors in response to climate change. Some species are expanding or shifting their ranges. The tufted titmouse, a songbird with an unmistakable call, did not occur during 1936-1947, but has become a year-round resident at the Leopold farm in Nina Leopold Bradley’s time.