If you put a "little !!" dissolved sea salt into the sugar water, this provides necessary 1500+ salt and trace mineral compounds for the hummers. It also keeps the sugar water from turning to vinegar, if any yellow jackets get around and saliva-spitting into the water, starting the yeast-vinegar cycle.

Our hummers tasting this get so feisty, that they will dive bomb the feeder from 100s of feet, get a taste, and feel so refreshed, that they will buzz off at top speed (with all those muscle electrolytes pumping through their body), and zip back for another drink. We can barely keep the feeder full as a whole swarm of migrants will suck a feeder dry in less than 5 minutes.

The "little" is not to human-taste of ocean salt water taste (3-4%), but ~1/8 teaspoon in a quart of sugar water. Some, just enough.