Fluctuating weather? ... that would be climate wouldn't it?
I cannot see a species adapting to cloud overhead.
Or a red sky at night.
Species adapt for their climate.
When a species starts dying because of climate change that is surely a warning.
And some people care.
They are not the same. I was referring to the amplitude of the stimulus, not the statistical mean of all stimulus summed over some arbitrary period of time. The warm blooded adaptation was in response to the extremes of weather, mainly temperature.
If we look at some arbitrary periodic signal with varying amplitude and mean, some adaption to the mean value isn't going to be very helpful, because it is the fluctuations that are the killers. They must be able to cover the variability on the stimulus if they are to survive. Obviously there are physiological limits to how wide the temperature gap can be for the warm blooded adaptation to be sufficient for survival, so an adaptation humans made was a large brain, which enables us to shape and control our personal environment. That again, not an adaptation to the mean value of a stimulus, but to the variability of the stimulus. The bats didn't have that last one.
Animals adapt to what is happening to them now, not some statistical measure invented by humans to tame chaos projected forward in time.