The transformation from winter to spring is one of the most anticipated seasonal changes of the year. Sportsmen, like every other human being living in a temperate climate, restlessly await spring's arrival.

Many different benchmarks telegraph the approach of spring. One thing that always amazes me is that each year within a day or two of ice out on local streams, the mergansers can be seen floating the open water hunting fish.

Another sign is the arrival of red-winged blackbirds, turkey vultures, and other birds that winter over in the south. Flocks of northward migrating Canada geese give further support that spring is arriving.

But, perhaps the most universal benchmark of spring's arrival in northcentral Pennsylvania is the awakening of a small amphibian, the spring peeper.

Peepers spend all of winter literally frozen solid. As temperatures warm in March and these small frogs thaw out and become active, they head downhill to the nearest wetland with enough standing water to lay their eggs.

Depending on the conditions, this migration can take place over several days or all the frogs may migrate on one warm rainy night. Such a migration can reach Biblical proportions, resembling the second plague on Egypt.

Who hasn't heard the chorus of Northern Spring Peepers on a warm spring night? The males of these thumbnail-sized tree frogs, perched on grasses and sedges at the edge of ponds or ditches, call mates with a shrill "peep" sound. They're well camouflaged and quick to retreat under leaves and stems. You'll likely hear hundreds before you ever see one. Because they are so easy to hear and identify, and may be very sensitive to changes in their aquatic habitats, peepers are becoming the subject of widespread environmental monitoring programs.

Last year the spring peepers made their debut early, on March 13. In 2005 they came out on March 27. This year, it appears that these harbingers of spring made their debut on March 24.

One of my favorite spring indicators is the return of the woodcock. This year I saw my first woodcock of the year on March 15. It seemed kind of out of place standing in the light dusting of snow that we had received that morning.

Eight days later, I witnessed my first woodcock mating display of the year, a sure sign of spring's arrival. Since then I have heard this same bird and several others as they have been performing their aerial mating displays.

The first two weeks in April bring another spring milestone -- the peak of the osprey migration through northcentral Pennsylvania as these birds of prey head back north. I spotted my first migrating osprey on March 31, perched on a dead sycamore snag overhanging the Driftwood Branch of the Sinnemahoning Creek, a mile below Emporium.

Sometimes at the start of April I see a half dozen ospreys on this stretch of Driftwood Branch while traveling Route 120 to and from Emporium. It seems to be a popular stopover, and these birds seemingly can be found everywhere along this stream in the weeks leading up to trout season.

This past week I also spotted two bald eagles on the same stretch of stream. Whether these birds are just passing through or thinking about taking up residence in the area is yet to be seen. The one was an adult and the other a juvenile who is in the process of changing over to adult plumage, a change that takes place once the bird attains five years of age.

I hope everyone makes time to get outside and enjoy the outdoors and everything that nature has to offer this spring.

On March 27, I witnessed a large gobbler breeding a hen. It was a sight to get any turkey hunter excited for springtime.

Although turkeys have been gobbling for some time, it seemed a little out of place seeing actual breeding taking place in March. Two weeks from today will be the youth turkey hunt. The following Saturday, April 28, will be the opening day of the traditional spring turkey season.