I heard them first on Saturday night, up near a friend's place in northern Baltimore County. Now they're singing in my own neighborhood. The spring peepers are out, and they're looking for action. The tiny frogs - less than an inch and a half long - emerge from their winter hibernation in March, with the first mild weather and warm rains. And the males begin calling for females. The breeding season is here and they're open for business.

These critters, formally Pseudacris crucifer, are nearly impossible to find, they're so wary and well camouflaged. But you can sure hear them. Each frog inflates its throat and emits a brief, one-note "peep."  But in an evening chorus of hundreds, they make a terrific noise that many have likened to jingle bells. The sound carries well away from the woody wetlands into adjoining neighborhoods, and for many people it's the first, most thrilling signal that spring has finally arrived. Forget the calendar, or the equinox. It's the peepers that mark the end of winter.

For me, they have also been a reassurance that our little corner of the county - and the wetlands behind our development - remain friendly to frogs and toads. Amphibian habitats are under assault almost everywhere.  And even our slice of wetlands - part of the Loch Raven Reservoir watershed - has long been targeted by road builders who want to construct a shortcut across it to speed commuters to their jobs. The peepers tell me each spring that the road builders haven't won yet.

If you'd like to get involved in helping to study and save the peepers and other frogs, consider Frogwatch USA.  If you just love looking at these guys, and listening to their calls, click here.