Through June and most of July, Millie and Roy walk with their colt while they forage.In late July, Roy and/or Millie begin to fly short demonstration flights across the nest territory, as Pi watches, sometimes spreading and flapping his wings.
On August 3rd, before Pi had fledged, Millie left Roy and Pi on the south side of the pond and flew to Bog Central (on the north shore) while Pi watched intently. Roy and Pi followed, not by walking around (their previous practice) but by swimming ~60 yards to join Millie. The swim lasted ~ 80 seconds. The pond is over 25 feet deep.
Still photos and a video Roy and Pi swimming across the pond. The last few still photos show three examples of colts swimming in earlier years.
Reports of Sandhill Cranes swimming are sparse. We have found no accounts of cranes swimming in staging areas such as along the Platte River.
In The Birds of Heaven, Peter Matthiessen reports that Whooping Crane chicks "swim well soon after hatching" and he credits Dr. George Archibald with an account of a Blue Crane adult that "swam and fluttered across open water to lead dogs away".