Cornell Ornthology tells me to change the sugar water in my feeder “before it gets cloudy” (how would I know it’s about to get cloudy?) because the sugar water ferments and turns to alcohol. While I understand that yeast does that to sugar in the production of beer, etc., what could be fermenting inside the feeder? It’s just sugar and water. I don’t put yeast or other organic stuff in there. Just sugar and water. Is it just from random bacteria? I don’t get this.
Wild yeast, the same thing you want to get when you start one of those water and flour bread starters.
Wild yeast is everywhere. Also, if your feeder is in direct sunlight all the time, that’s encouraging fermentation. Move it to the shady side of the house if possible.
Yes, wild yeast.
It does beg another question, though, do hummingbirds actually get drunk on fermented feeder ‘hooch’?
My understanding is that they won’t find it palatable and ultimately may not return to a feeder that they remember as having lousy food
It’s probably not just fermenting either. Hummingbird nectar doesn’t have anywhere near enough sugar to keep nasty bacteria and molds from growing in it. So it seems likely that dirty nectar could make a bird sick.
The hummingbirds themselves can bring yeast and bacteria to the feeder when they come to drink. Anything on their beak can end up in the feeder and, as you can imagine, warm sugar water works as a pretty good incubator.
This is one reason that some people want to get rid of hummingbird feeders. If they are kept clean they’re fine, but most people either don’t know or don’t make the effort. The hummingbirds can get infections that swell their tongues and they won’t be able to drink, and that causes the expected long-term consequence you could imagine. So if you have a feeder, keep it really clean. That means taking it apart and scrubbing it well so that any mold, mildew, bacteria, etc. doesn’t grow.
Will do. Thanks for the info.
I used to make cider without adding yeast. If you store unpasteurised apple juice for a few days it will ferment. Yeast is everywhere.
Life will find a way.
Alcohol will find a way faster.
Not in a straight line, perhaps, but faster. Reliably if sugar is involved.
As already answered, it’s yeast, which is floating in the air already. At its simplest mead is made by mixing honey plus water. When I was in high school we mixed up water, sugar, and rice in a container and it fermented, We were able to distill at least 80 proof from it.
I know the warmth would help fermentation, but wouldn’t the UV light kill microorganisms? I don’t know, just asking.
You made shochu! How was it?
He doesn’t remember.

change the sugar water in my feeder “before it gets cloudy” (how would I know it’s about to get cloudy?)
Are you only planning to refill your hummingbird feeder once?
Your high school let you distill alcohol? Damn, I wish my school had something like that.

I know the warmth would help fermentation, but wouldn’t the UV light kill microorganisms?
Sure, eventually, but the yeast will survive long enough to ferment a significant amount of the solution before that happens. The alcohol itself will kill the yeast too if it reaches 10-15% ABV, or as little as 5% depending on the yeast.
The best way to help out hummingbirds (and other wildlife) is to grow appropriate flowers. And not apply pesticides.

You made shochu! How was it?
Dunno. I didn’t try it. But one of the other guys in the back of the room was cutting it with water and drinking it.