Out of the clear blue sky you can hear them calling as they fly. In great v-formations, breaking rank occasionally to spiral higher on thermal winds, sandhills cranes on are the move. They’re leaving their winter homes along the southern Rio Grande now and heading toward the northern Rockies. Since sandhills live 30 years or longer, many of them have passed this way many times before. Seeing them return is like welcoming back an old friend. They’re an enduring sign of spring.