I don't ever recall seeing robins before late March in Iowa. I have seen a substantial number in central Iowa this January and February. What could cause this? What are they eating?
I have also seen quite a few robins. Last week there was a flock of 40-50 robins in my yard devouring the berries off my crabapple trees. Robins flock together in the winter because flocks have more eyes to discover new sources of fruit. Where they find fruit, it is abundant. Lots of fruit means flock members don’t have to worry about competing. Once the flock has depleted the food source, it will move on elsewhere. Robins are a migratory bird but their migration is a bit complicated. There seems to be great variation in where they spend the winter. It is not uncommon to see them here in January or February. Cold temperatures don’t hurt most birds as long as they have a good source of food. During winter robins eat mainly berries from trees, shrubs, and vines like crabapple, cherry, plum, dogwood, sumac, and wild grape. Come spring time the males start establishing territories and the flock disbands.