Dollarbird behaviour

[Wallaces <>]

I recently recorded these Dollarbirds performing what I will call  ‘head bobbing’ at Uriarra Crossing http://www.hbw.com/ibc/1286117. I haven’t located any reference to it (I do not have HANZAB) but it appears like Margaret Leggoe has captured it in her photograph http://www.hbw.com/ibc/1073599. Handbook of Bird of the World described a ’bowing display’ but only for European, Abyssinian and Indian Rollers.

 

Is anyone else familiar with this behaviour and the significance of it?

 

Steve