Jogging Pigeons

I saw a blurb in the local San Diego Reader about pigeons and why they bob their heads when they walk. I tried to get an online version to link to, but couldn't find it. (It must get posted later on, because the online version seemed to be a few weeks behind.)

But I did find a little bit about it online. It seems as though at some point someone did a study and found a potential answer by putting a pigeon on a treadmill. Interestingly enough, when the treadmill speed became equal to the walking (or jogging) speed of the pigeon, the head bobbing stopped.

And there are real physiological reasons for this. Their eyes are on each side of their head, so as they move they get two different images, which if they kept their head still while moving would register to them as a big blur. So bobbing their head forward allows them time to have their body catch up, in turn maximizing the time the head is still, keeping focused on one image.

I guess scientifically it's called optokinetic response. Avian vision differs from humans in that we are able to piece together scenes while continously scanning, while they capture whole pictures without piecing them together. So ultimately the pigeon ends up with a series of "fixed snapshot images, rather than a long, continuous blurry one."

Thanks to the following two links for setting me straight.

http://listserv.arizona.edu/cgi-bin/wa?A2=ind9505d&L=birdchat&F=&S=&P=16368
http://www.theanswerbank.co.uk/Answered/Question32820-1.asp?Page=1