Why are there so many robins in winter? Robins really aren’t harbingers of spring. They are found in the Treasure Valley year-round. The robins that breed here in the summer probably move south, and the robins from North Idaho and Canada probably come here for the winter, said Rex Sallabanks, wildlife diversity program manager for Idaho Fish and Game.

Why are so many flocking together? Robins change their feeding habits in winter. Instead of feasting on insects, they switch to berries. The reason you suddenly see large flocks all at once is that they change from solitary feeders to flock feeders, Sallabanks said. They go in large flocks and eat fruit off a tree until it is gone and then move on, he said. Sallabanks suspects that the cold snap brought robins from the Foothills and forests to town.

They look so fat. That’s because their feathers are puffed out to keep them warm — the way down jackets make people look big, Sallabanks said. Technically, they probably are leaner this time of year because keeping warm uses energy and fruit has little protein.