Spring has officially sprung, and the living world is bursting with activity again after the winter slowdown. Of course, the animals and plants outside don’t have the benefit of calendars, furnace heating, or a global food supply chain to live in comfort all year round and know when to start preparing for the new season. They rely on the changing cycles of nature to cue them and meet their needs, and every species has a unique rhythm based on the larger whole.
In the early spring, some of the first signs of activity can be seen on the forest floor, where early plants take advantage of the sun that the still-leafless trees let through. As the ground thaws and the snows melt, plants like Canada mayflower (also called false lily-of-the-valley) appear almost like magic, with loose mats of single and double leaves poking up through the soil. In wetter habitats, skunk cabbage leaves grow quickly to impressive size, with their purplish variegated flowering structures following soon after.
With these early plants come insects, many of which spent the winter as pupae, hidden in the soil or beneath the bark of trees where they would be shielded from the worst of the winter’s cold. These pupae release adult flies, beetles, and other insects ready to take advantage of the first soft, green leaves. These insects, in turn, are prey for the earliest spring migratory birds. Eastern phoebes, familiar birds that often nest above porches and in roof eaves, return around mid-March to eat these early-hatching flies and gnats. American woodcocks, which are actually sandpipers that have evolved to live far from the beach, hunt the newly-thawed soil for earthworms and insects, then congregate at the edges of wooded areas to perform their courtship “sky-dance” in late March and early April.
As March turns to April, more and more plants and animals resume their activities. Vernal pools are full of spring rain. The first warm, rainy night of spring usually occurs around now, which brings amphibians to these fish-free ephemeral wetlands to breed and lay their eggs. Zoo New England’s Field Conservation department are out at this time of year looking for rare salamanders as well as searching for new vernal pools to certify and protect. Choruses of singing wood frogs, with their chuckling ribbits, are often audible at vernal pools in early April. Mourning cloaks, beautiful brown butterflies whose wings are trimmed with blue and gold, spent the winter as adults and can be glimpsed flying through the woods. Hibernating bears begin to emerge from their dens in mid-April, and coyote pups are often born at this time, though they won’t be old enough to leave their dens for a little while yet. More and more migratory birds begin arriving and singing in mid- and late April, including the colorful wood-warblers. Birds that migrate only short distances or don’t migrate at all, like robins and blue jays, may be building nests and laying their first eggs at this time.
Up until now, the trees have still been almost entirely leafless. That changes as May flowers chase off the April showers, and some of the trees – like red maples – will flower at this time themselves. Reptiles like snakes and turtles have stirred from their winter hibernation thanks to rising temperatures, and they are foraging to fill their stomachs and replace the energy spent surviving the winter. The ZNE Field Conservation team likes to check in on all our radio-tracked turtles during this month so we can learn more about the habitats they’re using and watch for preparations to nest, which can easily occur in late May for painted turtles and snapping turtles. The emerging leaves and flower buds of many plants, like coltsfoot, Dutchman’s britches, and most of our broadleaf trees provide a buffet for the larvae of many insects. These, in turn, are eaten by the biggest wave of spring migrant birds, including more wood-warblers like Northern parula and black-and-white warbler and a variety of vireos, flycatchers, and swallows.
Wetlands are hotspots of activity as the waters are totally ice-free and wetland plants like cattails, buttonbush, and sedges have grown fresh green foliage. Harmless northern water snakes make their sinuous way through the shallows; bullfrogs, green frogs, and spring peepers are calling all through the season, and the ZNE Field Conservation team is bringing the wonders of wetland life to classrooms throughout eastern Massachusetts. Even in a pandemic year, our biologist educators are offering live streaming “virtual field trips” where kids can get a close look at native turtles, frogs, and other wildlife, as well as learning about the fantastic ecosystems they depend on to thrive.