Sandhill cranes, one of the oldest bird species, have been around for at least 2 million years. They mate for life and can live over 20 years. Though not endangered, they are losing their habitat to human population growth, plus getting hit by cars. They are beautiful, elegant birds and have an unforgettable trumpeting call. Their communication system is highly developed to alert for danger and reinforce the pair bond. The unison call is a duet done by a breeding pair: the male has a one-note call and the female a two-note call. I have seen one grieve and sit for days when their mate is killed. They migrate to Tennessee in certain times of the year and live in Florida year around.