My issue is I’ve never seen anybody – ever – empty a bulk bird food bin be it the plastic ones on the wall or the barrels on the floor.
Then wash them and disinfect them prior to refilling them.
You have no idea of what the “best used by” date is.
I’ve also come to find in many cases that the bulk bird food is actually more expensive on a part-time basis than the prepackaged name brand foods.
Keep in mind that normally they are refilled by simply adding more food to the vessel meaning the food on the bottom can potentially get moldy triggering diseases like Aspergillus.
It’s a risk that you take, you’ve been warned.
You’ve also indicated on the birds are on seed mixtures.
Seed mixtures by themselves will not provide a complete nutritional regimen for any pet bird in your household.
The fact that the zebra finches have laid eggs but none of them are fertile is also another sign that the birds may be malnourished.
It’s my understanding that zebra finches are relatively easy to breed.
To simplify your life I would advocate that you pick a line of food that is more complete and versatile for your 27 birds.
We like them because they are full-body and well-rounded.
They contain seeds, nuts fruits and pellets.
Both make great foraging foods and are available in food sizes that are appropriate for all of your 27 birds.
Hagen actually sucks the air out of their bags and fills them with nitrogen ensuring the lack of any growing live larva.
Kudos on keeping your birds flighted.
My guess is your male sun conure with a splayed leg doesn’t fly a lot not so much because of flying itself but landing.
The bird has to land on a perch grabbing it with a single foot which can be a bit of a challenge.
You may consider landing zones on the top of the cage that is flat so there’s room for error when the bird lands
I like to point out that the entire Hagen line changes relative to the bird size.
In other words rather than just including larger pieces of food and nuts for the bigger birds they actually of engineered the food to have higher protein for the larger birds because they will definitely burn more calories.
This is also one of the reasons that I asked if your birds are flighted.
Your BFA may not be flying now but I think with some gentle prodding he may be entice to add flight to his repertoire.
Flighted birds have greater caloric expenditures.
We also like to look at the sex and the birds knowing that a brooding hen requires more calories than a hen who is no interest in making babies.
Also published on Medium.