That has been my experience. I have hummers year-round, but the species vary, as do the numbers. I'm starting the heavy season now, when they'll drain three liters of nectar in a couple of days. I vary the number of feeders depending on how many hummers are around, and how fast they drink the nectar. During the "slow" season (January - March) I just keep one out and it takes 4 or 5 days to empty it. But, especially during the peak seasons, I get tons of birds, especially in the hour or so before sundown; they seem to call a truce and all the ports will be full, with others waiting in line hovered near the feeders. But it took months before I even got any birds, and years before I got this many.