From around the state I hear reports of the first migratory birds: sandhill cranes, hooded mergansers, and red-winged blackbirds. The numbers and diversity of birds-on-the-move will steadily increase through April and May, as longer days and warmer temperatures renew the availability of critical food sources. Stepping outside at night during the peak of migration, you can hear the sounds of their passing—distant contact calls, rustling wings, and a subtle wind that seems to carry spring behind it.