I surely agree with the pollen. In my original calculations, I tried to subtract the percentage of bees returning with pollen. Yesterday was just a huge pollen day. I think every bit of 1 of 3 and maybe even close to 1 of 2 were returning with pollen. The day before it was maybe 1 of 10 coming back with pollen, so obviously that does factor in. And I do also realize that water is often carried. That surely would confuse the issue, but it's just not a factor here right now. My hive is immediately next to a pond and I might see an occasional bee on the lily pads getting water, but not many at all. There just hasn't been any heat here all summer. It is a very hot day this year that gets to more than 80°.
In my little system, I have tried to only count only departures as I think that you can tell the difference between bees departing for foraging from bees on orientation flights. I try to watch 2 -3 feet away from the hive and the leaving foragers are rapid straight line bullets shooting through the wafting cloud of hovering orientation bees.
The big uncertainty to me is, "Do returning foragers come back empty? or only partially full?" or the reverse of that, "Does the hive send out lots of foragers if there's nothing to gather?" My instinct tells me no, but instinct can lead you astray. The whole basis of this theory is that if great numbers of bees are going out, then they must be getting something or the hive wouldn't be wasting precious honey resources of bees burning up lots of energy for fruitless flights.
Another unknown, which I would think would be a far far smaller percentage is how many are gathering propolis?
I really wish I had a hive scale, again not that it matters that much to me. It's going to be what it's going to be as far as honey flow and crop, but it would be neat to investigate further in this direction, but I do see a relationship in busy leaving activity and nectar filling the frames.
I'm leaving on vacation in a few hours and I won't have a computer where I'm going, so I won't be able to respond again until next week. . .