In traditional Chinese painting, the depiction of cranes often employs the technique of 'xieyi', or freehand brushwork, capturing the essence of the subject through minimal, expressive strokes.
The most plausible one, I think, is that he was referencing Giotto, who in the 14th century proved his artistic skill by drawing a perfect circle freehand - It's harder than you think.
A devoted student and friend, Green is now guiding people along Bedeau's original trails, as well as painstakingly scanning the freehand topography maps, diaries and logbooks Bedeau created over the decades.