Pigeon Behavior in Cold Weather

To the backyard naturalist, there is always - always - something fascinating, even amazing. I sincerely believe that God put me on this earth to be fascinated, amazed and delighted at His creation. This week, it was pigeons that surprised me and made me smile.

Through many Vermont winters, I have noticed that as the weather gets colder, pigeon behavior changes.
There's a school across from my workplace. All summer and into the fall, pigeons haphazardly place themselves on the school's slanted roof. As summer wanes, they move up to the top of the roof.
When the cold comes, they move from the roof to the power lines between our buildings.
The colder it gets, the smaller their personal (pigeonal?) space becomes. Around freezing, they may be a pigeon width apart. As it gets colder, they get closer. When it's really cold (subzero), they are touching or missing entirely from the wire. (I don't know where they go.)
I've enjoyed my little birdie thermometers. By the time I get to work, there they are, agreeing with me: "Baby it's cold outside!"
Earlier this week, I saw something bizarre. I saw that the pigeons thought it was about 15-20º F. They were spaced a half-pigeon apart. It was in the 30ºs that morning. Wait, what?
And then I realized that pigeons react to the weather the same way we do. Just think: in the summer, if it drops to 40º, we complain how cold it is. Why then, when the "January Thaw" comes, do we strip off our coats (and, at UVM, lie on the rooftops in bathing suits) and revel in the 40º warmth?
[I digress, but I am totally serious. Whether it is the January thaw or mud season, Vermont folk don flip flops and shorts. It's in the rule book. Some Vermont folk never stop wearing shorts. I'll still wear capris to work, but that's usually when I haven't done laundry.*]
What I had thought a measurable indicator of temperature (the pigeon spacing) turns out to be much more subjective. My dismay was only temporary. I can safely predict that as November turns to December, my bird-ometers will have re-calibrated.

*For the skeptic, here is a picture I took of my feet the year Lake Champlain flooded, affecting so many for so long. It was April, but you get the point.

Blessings and stay warm!