Pegasus and Charis, Thanks for your replies, and thank you for the link. I actually did read that post prior to initiating this thread. It made me even more concerned that our pigeon might need some sort of rehabilitation, in the company of other pigeons. Unfortunately, most of the city folks who kept pigeon coops on rooftops are not really around anymore, and the few who are still around, seem to be very particular about the types of pigeons they will keep.
The pigeons who live outside my Mom's building do come to the window if she puts food and water out, but she wasn't sure if it was such a good idea to start doing that, so she doesn't do it anymore. The pigeons outside do not really seem to take any interest in our pigeon at all - they were only interested in the food and water. On the other hand, our pigeon goes absolutely wild at the very site of them, even when he spots them flying in circles in the sky above.
We've been trying to come up with ideas to teach him how to get along on his own. My mom puts seeds on the floor in various parts of the apartment, hoping that this will teach him how to spot food from above (he likes the windowsills and tops of cabinets) and also to eat it off the floor. I don't know if this method has helped him at all. My biggest concern, however, is that he may not recognize a dangerous situation and he may not flee when necessary. There are cats roaming around outside all the time, and even some relatively large predatory birds can be spotted once in a while these days. Also, those awful people with nets have been seen in certain parts of the city. Our pigeon's own behavior also concerns me and I'm afraid he may think it's OK to swoop down and land on any person who happens to be walking around outside. People in general are not usually very nice to pigeons as everyone here probably knows.
Since I don't know a whole lot about pigeon behavior, I also want to mention that he has become very aggressive in the past month. He was extremely attached to my Mom in the beginning - he followed her wherever she went in the apartment, night and day. But whenever I visited, he would fly onto my lap or shoulder or head, for the sole purpose of pecking at me - and it can hurt! Now, he is much more aggressive with me than before. He does not follow my Mom around anymore and has even started pecking at her a little bit. Also, he has a large wire cage, but for the hours that he is allowed outside of the cage, he seems to have made himself a spot on top of a china cabinet. He's even been collecting dried twigs and leaves from my Mom's houseplants up there. I think he may be desperate for a mate at this point, but I don't really know if this explains the behavioral changes.
I'm sorry for this long post, but we love our pigeon and do not want any harm to come to him. We just don't know what we can do next to try to help him. We feel that it's cruel to keep him indoors with us when we can see how much he seems to want to join his family outside. Of course he does. So should we encourage the pigeons outside to come to our window, by putting food and water out there for them? I thought we could try the soft release method of putting the food out, and then scaring the pigeons away a few times a day for a few weeks. The main problem is that we would have to do this on a fire escape here, because the sidewalks are way too busy with people.