Interesting finding.
Dan Reiff
" By analyzing over 320 nest visitations in detail, the researchers saw that the wing-fluttering display prompted the mate who was being fluttered at to enter the nest box first, while the one who fluttered entered second, determining the order of nest entry and mirroring the "after you" gesture observed in human communication."

https://www.sciencedaily.com/releases/2024/03/240325112940.htm

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