HEAD BOBBING IN BIRDS etc

[darren.naish@port.ac.uk]

Re: head bobbing in birds, something that a few people 
have discussed here on the list over the past few days...

Ok, I'm going to display some crass naivety here but I 
thought that head bobbing in walking pigeons etc was due 
to their faster flicker-fusion rate and need to keep the head 
in a fixed location for as long as possible when moving. In 
other words, they hold the head fixed in space as their body 
moves forward to aid their vision. This is apparently 
something unique to neornithine birds so it wouldn't be seen 
in non-avian dinosaurs or basal birds. Err, given that 
Mickey is a vision scientist he may well know the answer 
here.. (in fact, I'm sure this has been covered on the list 
before).

The tail wagging of _Motacilla_ and some other passerines 
is social in function and not a consequence of their 
locomotion. Given that _Motacilla_ is primitively 
associated with running water, the wagging tail supposedly 
assists the birds in keeping track of one another. Notably, 
non-pipits that do this are denizens of shaded woodland 
habitats where a visible cue is also useful if you want your 
conspecifics to keep track of you.

-- 
Darren Naish
School of Earth & Environmental Sciences
University of Portsmouth UK, PO1 3QL

email: darren.naish@port.ac.uk
tel: 023 92846045