Phenology or Signs of the Seasons

“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 the study of the timing of life cycle events and their relationship to the environment (e.g., leaves changing color in the fall, birds migrating in the spring and fall, butterflies emerging from their Chrysalis). It tells scientists when events such as bird migration are happening on their usual schedule—and when an event might be out of time or place, especially in relation to the climate and change of seasons.

Phenologists observe and take notes on these events to try to discover nature’s patterns and rhythms. One famous phenologist, Aldo Leopold, kept records of wild animal and plant life on his Wisconsin farm from 1935-1948. His daughter, Nina Leopold Bradley, continued to carry on her father’s work, compiling a robust database spanning from 1976 until her death in 2011. She found that a substantial number of phenological events occurred much earlier in her data than they did in her father’s. But also know that even as our climate changes, some things (timing of events, individual species) are impacted more than others, and that living things are impacted differently.

To start learning about phenology, have your class work through the “Phenology at Play” Project WILD activity where students use hypothetical data to interpret how different organism’s phenophases (observable stages or phases in the annual life cycle) interact. This activity references the USA National Phenology Network and their Nature’s Notebook. Check out their site!

This activity will give everyone a good background to create a classroom phenology notebook to track the natural patterns of plants and animals at your school. Fill a three-ring binder with notebook paper and add dividers for each month. Record seasonal changes your students observe while outside throughout the year – sunrise/sunset times, hours of sunlight, temperature, changes in tree leaves and plants, animals you see and what they are doing.

Phenology can be used as a way to notice changes in the environment over time and is important to climate change science. If classroom records are kept and used year to year, even more data could be analyzed.

Check out Phenology Snapshots from University of Maine Cooperative Extension as a template to use historical photos and compare to images taken now. This kind of phenology study can help your students understand the role that climate plays in ecological relationships.

Other Helpful Websites

Aquatic WILD has a great appendix that can aid you in field investigations! Check out the following:

  • Inventory Methods
  • Using Local Resources ( is a great resource to find a local naturalist)
  • Field Ethics