Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Still frames ***(a–i) from a short film clip of one rook pair synchronizing or co-ordinating their behaviour. Frames (a–c), bowing; Frames (d–f), bill-wiping; and Frames (g–i), head-turning. See electronic supplementary material, video file 1.
