My theory is that you should have more birds each year, if you do everything right and no tradegy happens to your birds to keep them from returning. Could be that some birds are not smart enough to remember where you live, but I have had plenty of birds that I know returned because they would hover where a feeder had been 2-3 years earlier. Most people put the feeders in the best spots to view them, but I had remodeled and no longer put any feeders in front of the house; they still came to those locations. My hummers have always increased each year. I've only been at my current location for around 3 years, but I have more birds now. Actually, I was in temporary living here for over a year while the house was being built, so I did attract a few birds then. It is too hot to sit on my patio during the day, but I have just noticed what appear to be young birds in the past few days. My pattern is different here with lots of birds early and then late in the day. You are right about the sparring part; when you have more birds, they appear to get along better. When I only have 2 or 3 early on in the year, they fight all day long. Don't know how many birds you have, but 4 birds would prefer more than 2 feeders. Sometimes I have 8 birds with one on each feeder. At other times I might have 8 birds on 2 feeders or even 10 birds on two feeders. I think they claim a feeder or will be threatened to go to the next feeder instead of off to the woods. Keep us posted as to the number of birds each year, etc.

Soon after the females arrive they mate and then they go to forests usually to make their nests and then feed their young. About three weeks later or so the young come out and one sees more hummingbirds. I would assume that is what is happening with you, although it seems a bit early in your area. My numbers picked up a few weeks ago when the young started showing up. I still don't have very many, perhaps three or four at any time.