Silcock and Dinsmore, "Common Crane in Central Platte Valley, Nebraska, March 1999, and a Discussion of Prior North American Records" in Nebraska Bird Review (March 1999) 67(1).
On 5 March 1999, a report appeared on the listserver of a Common Crane sighted at 2:30 p.m. that day by Tammy VerCauteren (fide Paul Tebbel) about 2 miles east of Lowell Road in southeastern Buffalo County. The next morning, WRS drove to the location. After about 2 hours of searching, he refound the Common Crane at 8:57 a.m. among Sandhill Cranes about 50 meters south of Elm Island Road at a spot 2 miles east of Lowell Road. It was refound by SJD at 11:00 a.m. on March 9 northeast of the junction of roads X and 41 in northeast Kearney County. (The south channel of the Platte, just south of Elm Island Road, is the boundary between Buffalo and Kearney Counties.)
The Common Crane was easy to spot, as it was as tall or taller than the tallest Sandhill Cranes present and was paler than most if not all of them. In fact, it was so pale WRS suspected it might be Ieucistic, although SJD thought it to be no paler than the palest Sandhill Cranes, although probably unusually pale for the species; perhaps the early morning light was responsible for its pale appearance on March 6.
The bill was horn-colored and the crown, nape, and foreneck were black, leaving a pale gray-white line up each side of the neck, which terminated just before each eye. We could not discern any red coloration on the crown. Otherwise the plumage was pale gray. WRS saw the bird in flight on March 6 and was impressed by the entirely black primaries and secondaries contrasting strongly with the pale gray wing coverts. In flight, the black tail feathers were also revealed; when the bird is at rest, the much-elongated tertials and inner secondaries are folded over the gray tail feathers, giving a black and gray mottled look to the "bustle." It has been suggested that due to its paleness, the bird might be a Whooping Crane-Sandhill Crane hybrid, but the entirely black secondaries--a feature possessed by neither of the putative "parent" species--would appear to rule out this possibility.
Available at: http://works.bepress.com/stephen_dinsmore/17/