Interesting; when I start drone rearing in the next few weeks i'll be feeding vast amounts of protein, the winter bees have used their fuel and dying off and the stores are long gone or perished. Long way from the bees dragging in tons of pollen here and also too cold for foraging (again).
Seeing as you're firing up brood production using syrup and brood rearing burns through vast amounts of pollen I was wondering what else you were feeding, you can only load the box with so much stores before the winter (6 months ago now).
Ref pic of the amount of pollen we get here (in a few hours) but way off that -
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