Ask a Naturalist—How do we know that spring is finally here?

This article was written by Elizabeth Poulson, Minneapolis Park and Recreation Board Naturalist at North Mississippi Park


After a long winter, it’s difficult not to daydream about warmer days, blooming flowers, budding leaves and migratory birds making their way back north. During this transitional season, the arrival of spring in Minnesota can seem quite ambiguous. The weather and temperature varies so dramatically throughout the season, as well as year to year, that it could reach 75°F in mid-March or snow in May.

So, how does a bear know when it’s time to come out of hibernation? How does a tree know when to leaf out? Plants and animals don’t have calendars to know that the vernal equinox (the astronomical first day of spring) occurs on March 20 or 21. Instead, many of them take cues from physical changes in temperature and precipitation that happen seasonally. These shifts signal many organisms to enter new phases of their lives throughout the year.

The exact timing of the start to the spring season can be tricky to pinpoint as it relies on many factors. One of the most common methods used to determine if spring has begun is by observing when specific plants are budding or blooming and the appearance of certain animals. For instance, the first sighting of male red-wing blackbirds indicates to many that spring is upon us. The study of when these seasonal, natural events happen each year is called phenology.

Scientists and researchers who study phenology are interested in the timing of specific biological events in relation to changes in season and climate. This involves tracking the budding, flowering, seeding and dying back of plant species, or making observations of animal behavior including the appearance of migratory birds, the first mating calls or courtship dances, nesting, offspring sighting, plant visitation, and even backyard feeder visitation. If these events are recorded each year, trends begin to emerge over time. But what do these seasonal trends tell us?

The natural world is an interconnected system. How plants react to seasonal changes is important because they are at the base of the food chain—anything that affects plants can also have consequences for organisms that are reliant on them. The timing of events is particularly crucial because it affects whether plants and animals thrive or survive in their environments.

Phenology is one of the oldest branches of environmental science. Observations of seasonal changes have been used for centuries by farmers to maximize crop production, by nature-lovers to anticipate optimal wildflower viewing conditions, and by many of us to prepare for seasonal allergies. In Japan the flowering of cherry blossoms has been recorded for over 1200 years!

So, what signs of spring can you look for in your neighborhood? This month look for these common indications that spring has arrived:

*Swollen buds on lilac bushes are one of the earliest signs of spring that can be easily found in backyards or neighborhoods. In winter the buds are shriveled looking, but after there have been a few warmer days, the buds begin to hydrate or swell up.

*Eastern Bluebirds begin returning to their breeding areas between March-April. They are commonly found along forest edges or more open areas like restored prairies. They nest in cavities or bird boxes.

*Look for wildflowers such as crocus blossoms poking above leaves or snow, wood anemones and jack-in-the-pulpit in wooded areas, and marsh marigolds in wetlands.

*Spring evenings are filled with the many calls and songs of frogs and toads as they begin to mate. Western Chorus Frogs and Spring Peepers are some of the first to begin breeding.

Take a spring hike in North Mississippi Regional Park with a naturalist guide on April 12 from 4-5 p.m. to explore your senses in the spring season. Find out what nature observations people have made this season, by visiting our phenology board in the Nature Center at North Mississippi, then go for a walk and record your own findings. For more info about how to record your observations check out the Minnesota Phenology Network and Nature’s Notebook, which provide great opportunities for citizen scientists! Join us for free naturalist programs offered each weekend. If you have young children, then try out our Nature Nuts playgroup for kids under six with an adult to explore the outdoors while learning about seasons, plants, and animals.


April happenings at North Mississippi Park—Free for all ages unless otherwise noted
April 6—Bird Watching: Mississippi River Flyway, 8:30-10 a.m. Search for returning migrants, nesting eagles and other signs of birds starting a new year.

April 12—Senses of the Seasons Hike, 1:30-2:30 p.m. Reset your mind and body from overstimulation and discover how springtime piques various senses.

April 14—Family Funday: Weather Wonders, 1-3 p.m. Explore air, wind, clouds and rain through games, activities and experiments.

April 18—Homeschool Day: What’s in an Egg? 1-3 p.m. Which animals come from eggs? Find out as we explore different eggs and discover why only some animals lay them. Registration fee $5, ages 5-13.

April 20—Event: Earth Day Celebration, 11 a.m.-3 p.m. Show your appreciation of nature by joining in our Earth Day celebration! Lend a hand cleaning up the park, and then have fun with a variety of naturalist-led and self-guided activities.

April 27—Nature Art: May Day Baskets, 2-3 p.m. Craft a basket filled with handmade flowers and treats to leave on the doorknob of someone special.

April 28–Nature Photography, 11 a.m.-12:30 p.m. Go for a nature walk through the park with a practiced nature photographer and try to capture the spring season in a photographic moment. For ages 18+, registration fee $15.


Find registration for these programs and more at or call 612-370-4844 for more details. Do you have a question about nature in your own backyard? Then send it our way by emailing and it could appear in a future article. Like us on Facebook to stay in the loop about what is happening at your park.