"It's spring, it's spring," I imagine they're saying, though it's probably more like, "I'm hungry, I'm hungry. What do you have to do around here to get some flies!"
One year I first heard them on St. Patty's Day, so they are at least a few days earlier than that year. But what matters most is that they're here, and being hearty fellows they will weather the cooler weather that's blowing in here tomorrow.
If the color of spring is yellow and the scent of spring is hyacinth, the soundtrack of spring is what I heard last night: the music of tiny frogs welcoming the season.
(Look closely; there must be some peepers in there somewhere!)