gmr044@leah.Albany.Edu (Gregg Recer) (07/28/90)
In article <1990Jul25.021150.14574@ddsw1.MCS.COM> arf@ddsw1.MCS.COM (Jack Schmidling) writes: > Not only does this bird jerk its head while walking, but it > jerks its head when I walk, with the bird sitting on my > finger. > What is most interesting about this behavior is that he only > does it when looking in the direction that I am walking. If > he faces me or the direction from which we are coming, his > head does not move. I have held him out at arms length to > make sure it wasn't just my body, close to him, that was > filling his field of view. Sounds pretty consistent with an often-suggested hypothesis about such head-bobbing. That is that the head movement helps birds with their depth perception while moving. As a huge generalization, birds don't have binocular vision of the same quality as ours, consequently their depth perception is not so great. On the other hand, they have more in the way of wide-angle periferal vision than do we. So, when not facing in the direction of travel it seems to make sense that knowing the distance to objects out ahead wouldn't be too important. Gregg ******************************************************************************* "In future you should delete the words crunchy frog and replace them with the legend crunchy raw unboned real dead frog!!" -- Inspector Bradshaw, The Hygiene Division *******************************************************************************