I wouldn't be concerned. The engineers got that stuff figured out pretty well.

I change mine every other day, and don't have too many hummers at one time, so I usually only put in a few ounces of nectar at a time.

As often as you are changing the nectar it amazes me yours gets low enough to be concerned. I have a hand full of hummers, my feeder goes empty and needs to be filled about every 10 days at the height of its use. We returned from vacation to an empty feeder, filled it and they returned with in 24 hours. This time of year in particular they aren't going to starve if a feeder goes dry over night as you fear.

Here in GA where it's 90°+ all day and often 80° all night I'm afraid the nectar will ferment if I leave for 10 days. Probably not in a week, but I change it twice a week to be sure during July and August. Also only keep nectar refrigerated for about a week. In the past I've made up a gallon and kept it for a couple of weeks but it started to turn a dark color and I didn't trust it. It still tasted okay, but since then I've only been making a half gallon at a time which is plenty for 2 fillings of 2 feeders. Whatever's left over dump it out and then a few days later make up a new batch for the next week.

Could someone please explain why you need to boil your sugar water? Why can't you just add sugar to cold water and stir until dissolved, then put in the feeders?

I think people do it to kill bacteria and mildew etc. I clean my feeders to get rid of any mildew and heat water in the microwave to get it hot enough to make the nectar. Sugar won't dissolve as well in cold water, but it doesn't have to be boiling.

OK. Thank you David.