Although the vernal equinox — the official first day of spring — occurs on March 20, changes in our natural world are already heralding the end of winter. These changes are erupting on the land, in the sky and in waterways, as quiet, gray days begin to burst with color and song.

I know that winter is certainly on its way out when I see the conspicuous skunk cabbage (Symplocarpus foetidus) plant blooming in the woods. Skunk cabbage can appear as early as February, often popping up through snow as respiration from the plant can create enough heat to melt surrounding snow.

Skunk cabbage is a low-growing plant found in swamps, wet woods and stream borders. The name comes from the plant’s large, cabbage-like leaves and strong, fetid smell emitted when certain parts of the plant are touched or bruised. The plant mimics this putrid smell to attract flies, which pollinate the plant.

Another sign to look for are small temporary pools in woodlands and meadows known as vernal pools. Although they may be small and inconspicuous, these pools explode with activity as amphibians, like frogs and toads, congregate to call mates and breed.

The Greek word, “amphibios,” means creatures with a double life. Amphibians spend part of their lives living in water and the other part living on land. Most amphibians lay soft eggs in water. Toad and frog eggs hatch into tadpoles, which can only survive in water. As the tadpoles grow, they undergo a radical physiological change (known as metamorphosis) that transforms them into their familiar adult forms. 

Wood frogs (Rana sylvatica) migrate to vernal pools early in the spring. Their call is a hoarse clacking sound, reminiscent of a quack. The wood frog is an explosive breeder, usually laying a large mass of eggs in a few days then leaving soon after.

The spring peeper (Hyla crucifer), a tree frog, follows the wood frog by a week or two. Its unmistakable mating call, the peep, and large geographic range makes the spring peeper one of the most familiar frogs in North America. The mating call can sometimes be heard up to a half a mile away.

Another familiar amphibian is the American toad (Bufo americanus). Its habitat ranges from mountains to backyards. American toads are found anywhere there are moist places, plenty of insects to eat and shallow waters to breed. They may be warty on the outside, but their mating call is a pleasant musical trill.

In the waters, another change occurs as anadromous fish, like American shad (Alosa sappidissima), journey from oceans to rivers to spawn. The word “anadromous” comes from the Greek word meaning running uphill.

What’s really amazing is that these fish return to the same area in which they were born. How they accomplish this remains a mystery. Many scientists believe that this homing instinct may be due to an uncanny sense of smell and sensitivity to magnetic signals, polarized light and unique characteristics of their natal stream, creek or river. Prompted by rising temperature, American shad leave the ocean to return to smaller waterways, generally from March through June. 

Even if you miss these signs, you can’t miss the activity in the air. As the landscape turns green, and trees and flowers blossom, there is an explosion of worms, spiders and insects. And right on their heels, myriad birds return from their southern wintering grounds.

These birds nest in North America, but because they eat foods not available in winter — insects, seeds and pollen — they fly to South and Central America, Mexico and the Caribbean during the winter. As spring returns to North America, so do the birds, following their food to breeding grounds. 

More than 360 species of birds make this annual migration, including songbirds — warblers, thrushes, tanager and vireos — some raptors — hawks, kites and vultures — and a few waterfowl, such as teal.

Some of these birds are common to us: the American robin, Eastern bluebird, ruby-throated hummingbird, gray catbird, purple martin, barn swallow and chimney swift. Others, such as the red-eyed vireo, scarlet tanager, wood thrush and Cape May warbler, may be familiar only to bird watchers.

The osprey (Pandion haliaetus) is a spring icon. These large birds occur in nearly every corner of the globe, but nowhere as abundantly as the Chesapeake Bay. These large brown and white birds of prey are 2 feet long with wing spans of 4–5 feet. When in flight, their long narrow wings take on the shape of an outstretched M.

Their abundance around the Chesapeake is due to the availability of food; they feed exclusively on live fish. Curved, sharp talons and rough-soled feet are designed to hold onto slippery fish.

Ospreys hunt by soaring over water, periodically hovering on beating wings as they scan for fish. Upon sighting its prey, the osprey makes a spectacular dive. Folding its wings tightly, it descends swiftly and plunges feet first into the water, often submerging itself completely.

The Chesapeake Bay also provides the osprey with favorable nesting areas near water such as duck blinds, navigation markers or man-made nesting platforms. Offshore structures offer protection from predators, like raccoons, and rapid escape from other dangers.

Even though the month of March may roar in like a lion, take a moment to look and listen for spring. Flowers may already be blooming, warm evenings encourage singing frogs, fish are moving steadily upstream, and skies fill with joyous songs as more and more birds announce their arrival.