>
> As you can see, the hive numbers follow a clear trend.
> ​
>

I see several trends out of that chart.
Period One:~1927-~1940 shows a relatively stable set of numbers, although
perhaps a slight decrease.
Period Two:1940-1947 shows a clear increase.
Period Three:~1948-~1968 shows a clear decrease.
Period Four:~1968-~1991 shows stable numbers.
Period Five:~1991-~2011 shows stable numbers (although not at the level of
the 1968-1991 level).

Is there an overall decline from 1948-2011? Sure. But only if you look at
that time period in isolation. If you look from 1900-2011 its a minor blip
upwards, followed by more stable time periods than increases or declines.
If you look at those individual time periods listed above in isolation,
you'd have a different conclusion.

I think the questions should be: what happened between 1948-1968, then
again in ~1991 that are causing the otherwise stable hive numbers to act
irrationally?

Or, alternatively when you look at the "per hive" averages and compare it
to the time periods above, you'll see:
Period Two: Stable hive numbers, stable per hive averages.
Period Three: Decrease in hive numbers, stable per hive averages.
Period Four: Stable hive numbers, stable per hive averages until 1982, then
slightly more erratic per hive averages.
Period Five: Stable hive numbers, stable per hive averages from 1991 to
2005, and then again from 2005 to 2011 (although the two are not at the
same level).

It seems odd that period Three had a decrease in hive numbers, but averages
remained the "same."

So that gives you four areas that need explanation: (1) what happened
between 1948-1968 (I've read several times about hive numbers "returning to
normal" after the war, I wasn't alive then so I'm relying on what I've
read); (2) what happened in 1991 to cause a change in the "stable" hive
numbers; (3) What happened 1982-1991 to cause hive averages to fluctuate
while colony numbers remained stable; and (4) what happened in 2005 to
cause a change in "per hive" averages?

I don't know if I have answers to those questions.

But I don't believe I see any type of correlation with a decline in native
pollinator activity with honey bee per hive averages. I don't believe that
I've seen any studies that show that native pollinator populations were
remaining relatively constant, only to have marked changes between 1982 and
1991, or a sudden change in 2005 in particular. I would assume the native
pollinators, and competition from other hives, to be more progressive and
gradual. Perhaps it's faulty thinking though. I also don't see any type of
correlation between hive numbers and per hive averages. If so, a decrease
in hive numbers should show an increase in per hive averages, but Period
Three doesn't show that. Likewise, the increase in hive numbers from
1940-1947 corresponds with fairly stable per hive averages, when if
competition were involved causing the two you'd see a decrease in per hive
averages.

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