The lake near my home where herons nest every year is still frozen, but the birds are back. This morning I saw about a dozen of their haphazardly constructed nests in a grove of poplars on a little sandy island. If you’re curious what herons feed on when they don’t have access to open water: well, let’s just say they’re opportunists. Last year at this time I saw a heron standing motionless in knee-high grass, near a pile of brush. Suddenly it jabbed its beak downward, and emerged with a cottontail. As I watched, it shook the rabbit several times, flipped it in the air, caught it again, tilted its head back and swallowed the animal whole.