By Michael Caduto

The advance of climate change over time has been chronicled by observers keeping careful records of the dates when events occur in the natural world. You, too, can help to monitor climate change, and late winter is the perfect time to start recording your observations, just as the seasonal cycle gets underway. What date marks the first run of maple sap? When do the Red-winged Blackbirds return? When do the silver maples, American elms and lilacs bloom? When does the last frost of the season occur?

Recording and reporting the date when the Ruby-throated Hummingbirds return each springtime is one way to help monitor the impact of climate change on the world around us. Photo: Michael J. Caduto.

Keeping track of natural events and cycles is called phenology—a word that comes from the Greek phainestain, “to appear,” and logos, “study.” You can become a phenologist simply by maintaining a detailed record of how temperature, light and precipitation affect the life cycles of local plants and animals from year to year.

Famous phenologists include Carl Linnaeus, Henry David Thoreau, John Muir, Aldo Leopold and Reverend Gilbert White of Selborne, England. Thoreau created a detailed calendar of events for the natural history of Concord, Massachusetts. He charted the progress of plants and animals through the seasons during a ten-year period that ended in 1861, including the dates when birds returned in the springtime, when insects hatched, when flowers bloomed and when leaf buds unfurled. Thoreau’s phenological records, and their relevance to today’s changing climate, are the subject of Walden Warming: Climate Change Comes to Thoreau’s Woods, by Richard B. Primack.

In his landmark book on conservation, A Sand County Almanac, Aldo Leopold chronicled the natural world over time. Between 1935 and 1945 he made careful annual records of 145 natural events in Madison, Wisconsin—work that is still being carried on by his descendants. Leopold once noted that, “In June as many as a dozen species may burst their buds on a single day.”

I confess to being an intermittent phenologist. One of the lists I have kept includes dates for when the first hummingbirds appear at our Vermont feeders: 5/28/92 and 5/29/93 (South Pomfret); 5/22/95, 5/13/96, 5/13/97, and 5/15/98 (Union Village); 5/8/03, 5/11/04, 5/15/05, 5/7/07 (Chester) and 5/10/15, 5/11/16, 5/11/17, 5/14/18, 5/12/19, 5/6/20 and 5/6/21 (Reading). While this record is incomplete and varies geographically, it does show how consistent hummingbird arrivals can be in any one location, and it documents that hummingbirds are now arriving earlier to the Upper Valley than they were just 30 years ago.

On December 28, 2019—in the midst of the second warmest month of December ever recorded—I happened upon a surreal wildlife sighting while out for a walk along Rush Meadow Road in West Windsor. There, a red-bellied snake was sunning itself in the middle of the road, having been lured out of its winter hibernaculum by the 45° temperature and warm snowless ground. I placed it in a sunny spot well off the road, lest it get hit. According to Jim Andrews, coordinator of the Vermont Reptile and Amphibian Atlas (www.vtherpatlas.org), there is no previous historical Vermont record of a red-bellied snake being found active at any time between November 19 and early March.

Knowledge of the timing of natural events is also crucial for nursery growers, farmers, gardeners and others who rely on seasonal events such as maple sugaring, leaf peeping or skiing. Consistent records are invaluable for tracking the health of ecosystems, documenting changes in populations and marking the distribution patterns of plants and animals. Information about the hatches of disease-carrying insects and ticks can help experts monitor and predict the steady, climate-change induced march northward of threats to public health such as West Nile virus (mosquitoes) and Lyme disease (deer ticks).

As the 2022 season begins to turn, you can use it as an opportunity to begin contributing to the collective understanding of how the natural world, influenced by human activities, is changing over time. Simply choose the aspects of plant and animal life that truly interest you and keep detailed, timely annual accounts. Lilac flowers, for example, are an excellent indicator. Following exposure to an essential period of winter chill, lilacs respond by blooming in a very predictable way when the warm days of springtime arrive. 

Observations are best if recorded in the same place each year by the same individual, since this allows for the most meaningful comparisons through time. If enough people keep accurate journals of natural events in their own backyards—including dates and observations—this national database will create a picture of nature’s seasonal changes across the continent, providing scientists with vital information for studying global climate change and shifts in local weather.

Over the years, I’ve developed an appreciation for how our neighbors in the natural world can endure the ever-increasing extremes of seasonal weather in the North Country. Mark Twain got it right when he described New England weather: “There is only one thing certain about it; you are certain there is going to be plenty of it.”

WHAT YOU CAN DO TO BECOME A CITIZEN SCIENTIST: 

• Make your natural history observations count by entering the information into the online database of the USA National Phenology Network (www.usanpn.org). Observe and record data through UVM’s phenology website (https://www.usanpn.org/partner/volunteer-scientists).
• Report your sightings to iNaturalist online (www.inaturalist.org), or the Vermont Atlas of Life/Vermont Center for Ecostudies (https://val.vtecostudies.org/).
• Request a copy of the UMV’s guide to Plant Phenology in Eastern and Central North America by B.O. Blair and R.J. Hopp (Bulletin B677), by writing to: UVM Extension Service, Morrill Hall, Burlington, VT, 05055-0106.

Article adapted with permission from Through a Naturalist’s Eyes: Exploring the Nature of New England by Michael J. Caduto (University Press of New England/Chicago University Press).