Great horned owls start nesting in February. Their eggs take about a month to hatch—a long time for birds—so they have to mate and nest early. Their body mass and layers of feathers keep them warm.
Horned larks nest early, too, producing eggs as early as April. Because they start early, horned larks can produce two or three broods of chicks each season.
Migrating bluebirds, those famed harbingers of spring, arrive in Minnesota in mid-March. They eat the insects that become active as the temperature warms.
Male robins that haven't spent the winter here start to arrive when the average daily temperature is 37 degrees. Females arrive a few days, or even a few weeks, later. The timing means that males can establish territories before the females arrive, and the birds are "home" just as the ground is thawing and worms are emerging.
Male red-winged blackbirds migrate north and establish their territories in March. You'll know they've arrived when you hear their distinctive "oak-ah-LEE" territorial song. (Like female robins, female blackbirds arrive later than males.) They mate in late March or early April, and the eggs hatch a couple of weeks later.
Yellow-rumped warblers are among the first warblers to return in early April and the last to leave in early October. They sometimes travel in large flocks.
Or one that only looks new... Starlings molt once a year, in the late summer or fall. New feathers are iridescent black (with purples and greens), shiny, and have white tips. Winter beaks are dark brown. By spring, the white feather tips have worn away and the birds' beaks have turned yellow.
Canada geese are pairing up, nesting, and laying eggs. The 4-10 eggs hatch about a month after they're laid. Adults care for goslings for about two months after they hatch, and the young stay with their parents until the following spring.
Chipmunks are active now. They mate twice a year, once in the early spring, and again in June or July. The first litter of three or five babies is born in April or May. When the babies are six weeks old, they begin to take short trips out of the burrow. Two weeks after that, the young chipmunks disperse and find or dig their own burrows.
Oehlenschlager began tracking seasonal events in the environment when he was twelve years old. By the age of fifteen, he was making observations of bird behavior, nesting dates, and migrations on "data cards." Later, he broadened his studies to include the plants and other animals of Wadena County, an area he still studies today.
Dandelions are among the first plants to pop up in the spring. They use their long taproot to get water and nutrients, and absorb spring sunlight with their broad, spreading leaves. Some people eat dandelion greens in salad—they recommend gathering the leaves in the early spring, when they're still tender and less bitter.
Hepatica flowers open up in mid-March, when trees are still leafless and little else is blooming. They're tolerant of cold-temperatures and may last through mid-May before fading.
In April, while other plants are still dormant, the fuzzy, silky, silver-gray buds appear on pussy willow twigs.