William Wagner wrote:
If you have one humming bird feed you have one hummingbird. If you
have two humming bird feeders you have one hummingbird. If you have
three humming bird feeders you have one hummingbird if they are in sight
of each other. So place your feeds about your house not in sight of
each other that way one little beast can't protect it and you may have
many hummers .

I keep reading such presented as fact but in my experience I've not
found that to be true. I put out two feeders about two feet apart,
each with four stations, and have counted as many as six hummers all
feeding at once, and with others perched on a wire fence mere inches
away or hovering within a few feet.

http://www.hummzinger.biz/humzinger.htm

I won't buy feeders with a plastic food container, plastic becomes
etched and breeds bacteria. I use only glass, scrubbed once a week
with salt and soaked over night in a 4 to 1 water and white vinegar
solution... never use soap. It's really not necessary to feed
hummers, they do fine foraging as they've done for millions of
years. We feed hummers strictly for our own amusement, so it
behooves us to feed them responsibly.