Phenology: the Preserve through the seasons

Fiddleheads by Glenda Denniston.

This web page is an introduction to the science called phenology, which studies natural events—season to season and year to year—in an effort to understand the natural cycles of ecosystems.

Watching the seasonal cycles of its plants, animals, and physical systems is a fascinating way to deepen your appreciation and understanding of a natural area like the Lakeshore Nature Preserve.

What is phenology?

Phenology is the study of observable and measurable events that tend to occur annually.

Types of annual events include:

  • the dates that Lake Mendota freezes in the winter and thaws in the spring, or
  • the date in early spring when male redwing blackbirds first, begin singing to declare their territories in the vicinity of University Bay.

Phenology can be enjoyed by everyone, no matter how much or how little they know about natural history. Small children can understand its core concepts, and senior scientists still experience wonder at the insights it generates. Phenological observations are also used to understand how our climate is changing.

Start looking!

How do you get started observing these natural cycles? One great strategy is simply to identify a trail you especially enjoy, and walk it every week from March through July. Repeatedly visiting the same places in the Preserve across the months of a year will reveal how those places change in predictable ways.

Click on each of the season pages below to find a list of natural events that are easy and fun to observe. Find your season and your path—and start looking!

Recording the rhythm

Nature watchers have observed and recorded the timing of events like these—and countless others—from time immemorial. This is reflected in historical records, poetry, and folklore from around the world.

If watched and recorded carefully, the historical record of past seasonal change can be used to predict future events as well. In the seasonal examples we offer below, we’re essentially predicting the future for you: if you want to see Jack-in-the-Pulpits in bloom, for instance, go looking for this plant in early spring.

Many phenological records note the first occurrence each year of a particular biological event, such as the first observed blooming of a particular wildflower. But phenology is not limited to recording just the beginning of an event. It can also include when that event ends: for example, when the nesting period for a particular species of bird is complete.

Lake ice cover phenology chart by Robert Bohanan.

Phenological record-keeping isn’t limited to biological events. Phenology includes observations of the timing of physical phenomena in a given locale, such as the dates of freezing and thawing for Lake Mendota collected over the past 150 years. These have provided scientifically valuable information showing how a particular lake in the Midwest is responding to climate change.

When these recorded observations of Lake Mendota are combined with similar observations of lakes, streams, and rivers throughout the northern hemisphere, the result is a compelling history of how ecosystems are changing in response to changing climate. In fact, phenological records are providing some of the most convincing evidence for climate change.

Beyond their scientific value, phenological observations are easy and fun. They allow us to observe the pulses and rhythms of places we hold dear. We can also share our observations with people at different locations, and the combined records can then paint a picture of changes in the timing of similar events across different landscapes. Simple though such studies may seem at first glance, they have been quite central to our understanding of climate change.

Learn more!

The following are excellent sources of information if you’d like to deepen your knowledge of this fascinating science of phenology:

Wisconsin Phenological Society

EEK! Environmental Education for Kids

USA National Phenology Network

Aldo Leopold Foundation Phenology: Stan Temple Talks Phenology