Hi Mint5jf,
I'm south of Mulberry, if you know where that small town is in central Indiana. I'm also concerned about the lack of hummer activity. I've only been feeding for three years, but this year there is very little activity compared to the last couple years. I had my feeders up early this year to catch the first arrivals. I change my feeders every other day, and I make my own 4:1 sugar water solution. In the past couple years, I would easily have four to six of them at a time at the feeder and a couple more waiting nearby for their turn. This year, I've had one female and one male, and only once have they been at the feeder together. I'm assuming there's just the two of them simply because I'm not observing multiples at the feeder as in past years. I have changed nothing about the feeder location or anything to have discouraged them, so I'm as stumped as you are.
This has been a great season so far with the flowering trees and plants, and I wondered if they were less dependent on the feeders this year in light of nature's bounty. But I have no way to be sure. My parents live north of Mulberry, and have commented that they aren't seeing hummingbirds at their feeder like in the past.
I sure hope some folks will add some insight, because it's a concern. I'll hope the answer is that nature is providing for them given that for the first spring in a couple years, the hail/freeze/storms didn't damage the blooming trees/shrubs.