THE head-bobbing so characteristic of walking pigeons is an illusion.
杏吧原创s have long suspected that a pigeon鈥檚 head is locked in space with the
body moving beneath it. Now Nikolaus Troje of the University of the Ruhr in
Bochum, Germany, has the measurements to prove it (The Journal of
Experimental Biology, vol 203, p 935).
Troje videoed pigeons from different angles during a variety of activities,
including courtship and feeding. Then he and a colleague analysed the video
frame by frame. They found that the pigeons鈥� heads were actually motionless
while they 鈥渂obbed鈥�, possibly allowing them to process images and judge
distances. 鈥淥ne function might be that the retinal image stabilises during this
hold phase,鈥� Troje says.