The Short Days Are Over

December 22, 2009 By: Marshall Cutchin

Or just beginning, if you happen to live in the southern hemisphere.

But did you know that in the northern hemisphere, even though the number of hours in each day has begun its seasonal increase, the sun will continue to rise later each morning for another few weeks? (Don’t worry, it’s made up for by even later sunsets.)
I’ve long had a theory that plants, animals, and insects respond as much to the photo-length of days as they do temperature or barometric changes (guides need all the reasons they can get to explain fish behavior). Perhaps it goes some way to explain why insects that are most active in winter tend, like December baetis, to be darker in color than their summer cousins (e.g. sulphurs) — they need and absorb all the light they can get. It just adds to the mystery, but offers another reason to feel positively phototactic this time of year.
I’m going fishing.

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