Friday night, with my QSI, imaging and guiding was perfect (all on the western side of the mount). Stars were round at 400 x and I was very happy with the performance until clouds ended the session. However, Saturday, all was fine until shortly after pier flip, where the guiding was very erratic and I had trouble getting a good calibration. Also, it appeared that SGP's guiding traces did not match PHD2's traces in RA and DEC. I thought that I had dragging cables, checked and re-arranged to to ensure good, but soon the guiding was as erratic as before. I was not getting good images, but was getting tired, so I aborted the sequence, parked the mount and went to close the observatory. That's when I discovered a very large Pigeon in the observatory. The bird was apparently trying to roost on my telescope. So, in the future, if you can figure a way for a bird alarm, I'm all for it.