Xref: utzoo rec.birds:2455 sci.bio:3347 Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!mcdchg!ddsw1!arf From: arf@ddsw1.MCS.COM (Jack Schmidling) Newsgroups: rec.birds,sci.bio Subject: HEAD JERKING OF WALKING BIRD Message-ID: <1990Jul28.033019.5059@ddsw1.MCS.COM> Date: 28 Jul 90 03:30:19 GMT Reply-To: arf@ddsw1.MCS.COM (Jack Schmidling) Organization: ddsw1.MCS.COM Contributor, Wheeling, IL Lines: 67 Subject: Re: HEAD JERKING OF WALKING BIRDS I have a problem with Pnews here in that it makes it look like I want responses in email when I really want to discuss things on the net. The following is typical of the responses I got to the question I posed.... >You realize, of course, that this is a violation of Federal law. ............. >If it is one of the species you can legally possess, let me know, and I will comment on your behavioral questions. ............ I fully accept the criminal nature of the act which I implicated myself in, but having watched a kestral snatch the first two fledglings off the nest in my bathoom window, I was in no mood to concern myself with the letter of the law. The most amusing response (excerpt above) was from someone who refused to even discuss the issue if the bird in question was a mourning dove. ............ One responder suggested that the behavior was an adjustment for continually changing focal distance. This seems like a reasonable answer but I can't help but wonder why these birds have such a limited depth of field. One assumes that it must be on the order of 1/2 inch because that amount of head movement seems to put things right again. I suppose the answer lies in what fantastic things they must be able to see in that very restricted range. A few more experiments with the bird at arms length, seem to support the focus theory. If I was very careful to make sure he could not see me, he did seem to jerk his head no matter which way he was facing. ................. On a slightly different point, is there really any way of knowing what a bird is looking at? For example..... He will suddenly cock his head and look straight down at the floor and........... However, someone on the opposite side of the bird would swear that he was looking straight up in the air. ...... just heard the familiar wing beat and find Charlie in the bucket of sunflower hearts on the back porch. For the past five days, he has left around dark and returns late in the morning to "visit". Oh! Oh! the doorbell.... must be the bird police. Run Charlie! ............... If you insist on sending email, please send to arf@gagme NOT to the address in this header.