I just did some more looking and found this..
"You've heard of the playground bully. Hummingbirds, especially males, often display the same kind of territorial and aggressive behavior over nectar sources. They are known to chase away competitors for the same feeder. A "bully" may be squelching feeding opportunities for other hummingbirds in your neighborhood.
Diffuse this behavior by offering several feeders - in different locations around your yard. An aggressive male can't possibly defend them all. Placement is crucial. Be sure to locate feeders high enough to deter predators, but in plain sight near flowers or windows for a good view. Hummingbirds also like to have a branch nearby from which they can observe cautiously before approaching the feeder. "
So maybe the answer is more feeders = more birds?
But then I found this..
"Hummingbirds instinctively know a feeding source that is denser in sugar, and a more aggressive bird will make that feeder its own. Smaller species will then flock to the second feeder. "