Ice covers have begun to leave southern Minnesota lakes, and the first common loons have arrived. We have seen an increase in the numbers of waterfowl, such as canvasbacks, redheads and ring-necked ducks.

Maple syrup producers report some excellent sap runs since March 29 that have continued into this first full week of April. In the Twin Cities and area, crocuses are blooming along the south sides of homes.

The ground is thawing and unlocking the food supply of earthworms and insects for the early migrating American woodcocks. Observers in southern and central Minnesota have been hearing the "peenting" sounds made by these birds.

Woodcocks are stocky, about 11-inches long, with long bills, short necks and a dead leaf pattern on their upper bodies. They begin their calling and display flights soon after they return from the southern states.

The arrival of spring is announced by the noisy courtship displays and vocalizations of birds, and the American woodcock adds its special music at a quiet time of day. Its performance usually begins soon after sunset and ceases when the glow in the western sky disappears, only to begin again in the morning twilight or on moonlit nights.

A person who wants to attend a woodcock concert must find the correct habitat. Woodcocks nest in wooded or brushy uplands not far from wet lowlands, and they perform their courtship displays on open pastures or fields. I have taken whole school classes out to observe this spring happening. The bottom lands of the Minnesota and Mississippi rivers provide good observation spots.

The loud vocal "peenting" sound is uttered every few seconds as the woodcock struts about on the ground. The male gives elaborate flight displays performed for the benefit of his mate. Suddenly he rises and flies off at an angle, circling higher and higher until he reaches a height of perhaps 300 feet and looks like a speck in the sky. The upward flight is accompanied by twittering musical notes. As the bird flutters back to earth, a series of chipping whistles, both produced by vibrations of outer wing feathers, complete the aerial performance. He soon begins his "peenting" notes again, and the whole act is repeated until it's time to quit for the night — or morning.

Jim Gilbert has taught and worked as a naturalist for more than 50 years.