I was in Chattanooga yesterday and took an hour off to bike the Riverpark, a fabulous linear park that starts in downtown, then stretches for ten miles along the Tennessee River.
The highlight of the ride was a flock of sandhill cranes (Grus canadensis) overhead. They were flying along the river, wheeling occasionally in a big disorganized circle, then reforming into a northbound V. I suspect that they were looking for somewhere good to feed and were disappointed by the lack of swamps in the urban center, so they chose to move on. They are likely part of the congregation of overwintering cranes at Hiwasee Refuge, a gathering that numbers in the tens of thousands is the largest wintering aggregation of sandhills outside of Florida. These Tennessee birds return to the upper mid-west to breed.
Aldo Leopold wrote of these birds, “When we hear his call, we hear no mere bird. We hear the trumpet in the orchestra of evolution.” This is no accident — the trachea of these cranes coils within their sternum (chest bone) to make a resonating instrument very much like a trumpet. Both sexes call, often in vigorous duets.
For some remarkable footage of cranes in flight, see this almost dream-like series of shots of common cranes flying over Venice.