How do birds keep warm in the cold weather

[Catherine]

A wildlife Photographer has done a video explaining how birds keep warm in the cold weather. It really is remarkable.
Even tiny little balls of fluff can keep themselves warm.

https://pethelpful.com/pet-news/wildlife...-stay-warm


It is really cold in Toronto right now and all the wild birds I see have their feathers puffed out. 
All the pigeons who hang around the subway stations have their feathers fluffed up and they are staying still so that no cold air gets in.

I also noticed that the birds come early in the morning to feed. After a cold night they need the food for energy.
They are not even waiting for sunrise. I can just barely see them in the predawn darkness.
To help them out I bought extra black oil seed to add to their mix. They seem to like it.
Anything to help my wild bird friends on a cold day.