I forgot to mention in my last post that while we were in London we went to Trafalgar Square, for the first time in years. We noticed straightaway that there were no pigeons in the square - there used to be thousands flying around. Then we saw the reason - a falconer with two Harris hawks. He and another falconer split the week between them, and spend a few hours each day in the square, flying their hawks. Some of the pigeons are canny enough to return to the square when the falconer has gone (so the falconers vary their schedule from time to time). But there are no longer pigeons nesting on the surrounding buildings, which are much cleaner than they were. The falconer said that in old films and newsreels, the lions at the foot of Nelson's Column are white with droppings - now they are clean and shiny black.
The Harris hawks are beautiful birds. Perhaps if you only ever saw pigeons occasionally, in ones and twos, it would be easier to appreciate them.