Hummingbird feeders are exposed to bacteria and yeast, bacteria and yeast like sugar and they like warmth. Hummingbird nectar recipes usually call for around 20% sugar (1:4 water ratio). That is nowhere near high enough to deter microbial growth, for instance sugar syrup is around 70% sugar on average, and that’s high enough that it will lower the water activity (aw) to a point where bacteria will usually not flourish - but still may if the container is badly contaminated, or sitting in a warm location for long enough. For honey it’s 80+% sugars and usually around 17% water, which is a low enough water activity that it keeps it safe from microbial growth. If you want to go down a whole rabbit hole on this, search ‘water activity honey’ etc and you’ll see a bunch of interesting research and industry guidelines.
Anyway put that all together and yeah, you need to clean hummingbird feeders regularly or they become bacteria & yeast farms, like the article discusses.
I’m surprised that water with so much sugar in it can spoil.
Hummingbird feeders are exposed to bacteria and yeast, bacteria and yeast like sugar and they like warmth. Hummingbird nectar recipes usually call for around 20% sugar (1:4 water ratio). That is nowhere near high enough to deter microbial growth, for instance sugar syrup is around 70% sugar on average, and that’s high enough that it will lower the water activity (aw) to a point where bacteria will usually not flourish - but still may if the container is badly contaminated, or sitting in a warm location for long enough. For honey it’s 80+% sugars and usually around 17% water, which is a low enough water activity that it keeps it safe from microbial growth. If you want to go down a whole rabbit hole on this, search ‘water activity honey’ etc and you’ll see a bunch of interesting research and industry guidelines.
Anyway put that all together and yeah, you need to clean hummingbird feeders regularly or they become bacteria & yeast farms, like the article discusses.