>> As well as the cluster functions, the surrounding environment can
>> influence the dynamics of heat production vs. insulation via the three inexorable forms of heat loss: conduction, convection and radiation.
>> *Probably the main killer, as pointed out by Seeley, is convection*.
> Why do beekeepers insist on over-ventilating hives. We know what bees choose in nature -- single small entrances.
Hold on, citing Seeley thusly misrepresents his work - most of the *bees* in North America are kept West of the Mississippi. But most of the *beekeepers* are East of the Mississippi, and South of the NH/MA state line.
This means that most (hobby) beekeepers have conditions very different from those experienced by Tom Seeley, who does not come south for his bee work. The climate is very damp by comparison, even in winter.
Morse and Seeley found that FERAL hives "around Ithaca NY" seemed to prefer and entrance size of 2 to 5 square inches. A 2 inch diameter hole at about 3.14 square inches, or just in the middle of what the bees find most desirable. In Ithaca, that is. (Papers attached, its criminal that they are still paywalled 40+ years after publication.)
But, manufactures of bottom boards offer a 3/4-inch deep entrance, or a 3/8ths-inch deep entrance. So:
0.75 X 14.75 ~ 11 sq in
0.375 x 14.75 ~ 5.5 sq in
How would they be so far off specs published back in 1976?
If a beekeeper wants to adopt Seeley's findings on entrances, he'd leave an entrance reducer on year-round. But we don't, as our managed colonies are 2x or 3x the population of typical tree-cavity feral hives, and the "traffic jams" alone are problematic. But in winter, many inland beekeepers DO reduce entrances to Seeley's suggested sizes or smaller, so some winters are dryer than others. (Do you run a humidifier in winter? Do you get little static shocks when you touch a doorknob after walking across an oriental rug? If so, you have a dry winter. If not, you may not.)
Further, Seeley warns that he has very dry winters, so his feral bees need the persistent condensation that beekeepers to the South (including me, only 200 miles southeast) strive mightily to avoid.
Nb: My bees are exceptionally "damp", as I keep bees on (a) Manhattan, a small island just off the eastern seaboard of the formerly "united" states of America (b) a small island in the Caribbean (b) yet another small island in the Canaries. So, my bees are far warmer and damper than Ithaca, NY could ever be.
I am sure that this question is frequently-asked, as he talks to beekeeper groups often, so I'll not bother him again. Here is what he wrote a beekeeper about this, quoted from a 2015 post to another beekeeper discussion group:
https://www.beesource.com/threads/tom-seeley-raw-data-top-entrances-vs-bottom-entrances.319837/
https://tinyurl.com/2p97bt4m
"In my tests with paired nest boxes, the bees
expressed their preference for a nest cavity with a bottom entrance over one
with a top entrance in the following way: 8 swarms occupied the bottom
entrance nest box and 2 occupied the top entrance nest box. So it is a strong
preference, but not a black vs. white one.
Regarding the functional basis of this preference, I suspect it has to do with
the energetics of overwintering in a cold climate. I will attach a recent
paper that looks at the strongly negative effects on energy consumption of
having a top entrance (in addition to a bottom one). But it sounds like
where you live, the bees have an even bigger concern over excess moisture.
Where I live, where winters are cold and dry, it looks like the bees depend on
some condensation in the hive for water homeostasis during winter, when they
are confined to the hive and cannot collect water. Without this condensation,
they get wicked thirsty, something that I see clearly with the bees in my
observation hive, which is mounted in a heated room (my office) so there is no
condensate for the bees to imbibe."
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