Flocking Robins Fill a Tree

"This morning (Feb. 9) I discovered the aspen tree in my side yard was filled with robins!" wrote an observer in Colorado. "There were more than 20, sitting all puffed out for warmth, waiting to feel the first rays of the morning sun. Both my neighbor and I have bird feeders up, but they weren't eating, just chilling!"

What might be some advantages for winter robins staying together in flocks and traveling together in waves? You'll explore that question in this week's update.
Image: Diane Sickles