Jim, thanks for this link. But this requires super-human brown power. The novel Old Sarum is a much easier read that tells the same story in a human way. If any of you (subscribers) have not read that, I highly recommend it. It is historical fiction, to be sure, but not too far off the wide path. Not to say Jim's link here is not much more scientific--it is. Craig Kilby P.S. If you are interested in the book Old Sarum, please google it on your own and do not post a question here asking how to find it. You have a computer. Use it. On Feb 21, 2013, at 12:49 AM, Jim Bartlett wrote: > http://www.jogg.info/32/bird.htm