If you’re a faithful keeper of a garden journal, or wish you were better at recording your thoughts and observations, Coastal Maine Botanical Gardens, teaming up with the University of Maine’s Cooperative Extension and Sea Grant, is once again offering “Signs of the Seasons,” a citizen-science program enlisting volunteers in plant and animal phenology — the study of seasonal cycles and the timing of events such as when birds make their nests in the spring, when berries ripen in the summer, or when leaves change color in the autumn. To more fully understand how seasonal cycles are shifting, participants in the Signs of the Seasons program, by becoming trained to observe and record plants and animals living in their own communities, can help scientists document the local effects of global climate change. Through their observations, volunteers can create a detailed record of the region’s seasonal turns, a record then made available to collaborating scientists.

Climate scientists have found that changes in the historical timing of plant and animal phenology is one of the most sensitive indicators of the local effects of global climate change. Farmers, gardeners, fishermen and many others have been recording their observations of seasonal phenology changes for centuries. A patchwork of records exists in notebooks and logbooks, ledgers and bills of sale. Matching historical observations with more recent ones has allowed climate scientists to identify shifts in long-term phenology trends that closely match records of Earth’s warming temperature. Phenology records can help scientists fill in gaps and get a more complete picture of the local effects of global climate change. They also help scientists predict changes that may come in the years and decades ahead, which will help in understanding, responding to and preparing for a changing climate.

Mainers who take part in the citizen-science effort will be joining an august company of past observers. For example, a well-known New England observer is naturalist and philosopher Henry David Thoreau, who, in the 1850s, recorded the plant species and flowering times that he observed near Walden Pond in Concord, Massachusetts. Records kept by Aldo Leopold, acknowledged by some as the father of wildlife conservation in this country and best known as author of “A Sand County Almanac,” have yielded important insights into long-term changes in phenology — largely, shifts toward activity earlier in the year— in Wisconsin. In California, research in which historical observations made by field biologist and zoologist Joseph Grinnell were used has contributed to the evidence of changes in the ranges of small mammals and birds in the Sierra Nevada Mountains. But it isn’t just famous naturalists whose records are contributing to the body of current research. Current climate scientists have found that there was a surprisingly large number of bird watchers who record the arrival dates of migratory birds in the spring and who were willing to share their observations. These bird watchers sometimes kept their own journals of arrival dates around their homes, towns, or special locations favored by migrating birds. Other bird watchers keep records as a part of clubs, such as the Nuttall Ornithological Club, which has been meeting for over 100 years in Massachusetts. Historically, club members recorded the first arrival of birds across the region, or at specific locations, such as Mount Auburn Cemetery — a favorite birding locale on the border of Cambridge and Watertown, Massachusetts. However, the oldest records in Massachusetts again came from Concord and were gathered by Thoreau, who made a table of bird-arrival dates during the 1850s in the same style as his plant tables.

In addition to birds and plants, insects are a key missing link in the story of the ecological responses to climate change. While there is not as much collected journal observation on insects, scientists have found data describing butterfly phenology, a group known to be sensitive to temperature, by reading labels in museum collections, where there is historical information on when the insects were actively flying. Today, many butterfly clubs post pictures and dates of appearance to their club websites. Combining past museum collections with modern sightings is currently providing a method to examine the effects of climate change on this insect group.

Phenology changes are easy for volunteers of any age to observe and record. Gardeners already spend a lot of time outdoors, noting the first robin of spring or the first and last trees to lose their leaves in autumn. Those who choose to participate in Signs of the Seasons can follow as many indicator species as they’d like, identifying and marking one site or several, where they’ll observe these species throughout the year. As more observations are recorded, the difference between short-term variability and long-term trends will become clearer. Currently, there isn’t enough data about these changes for many important species in Maine, but participants in the Signs of the Seasons project will help fill that gap. The next training session will be held on Monday, April 29, from 12:30 to 3:30 p.m. at Coastal Maine Botanical Gardens’ Bosarge Family Education Center. For more information about the program and to register online, visit Maine Cooperative Extension.