Birds of a Feather and Why Do They Stick Together

I have lived on this planet for a long time and you would think I had seen and understood much, but at a recent flying lesson I found out that my knowledge obviously had some gaps. As I go about my business, I have noticed for years that birds sometimes just sit around doing nothing, but I must admit that I never thought much about it. Fast forward to a flying lesson a few weeks ago, when the remnants of a hurricane were in the air. So I am laying there listening to the teacher instruct my son and he is explaining that the lower the air pressure, the harder it is to keep the plane in the air and the more fuel it expends flying. Obviously, something a pilot needs to know. So then he uses an example, he turns to me and he goes "You ever notice birds sitting on power lines?" Well, yeah, of course I did and said so. He then says to both of us, "the reason they are sitting on the power lines or other thing is that in the low air pressure, it is harder for them to fly and it expends more of their energy. So they tend to take frequent breaks, thus the sitting on power lines. It was like this light bulb went off in my head and for the past month or so I have kept track of when I see the birds on the power lines and billboards, as I walk to work. Yep, it definitely occurs on days where we have lots of fog and water in the air. Interesting and something new to understand, especially as our rainy season is starting to kick into gear.