Yes if they can.
Yes, the eat caterpillars.
No
Both are thrushes, members of the family "Turdidae".
Most of them... robins, chickadees, bluebirds...
Not really.
For the same reason you do. Bluebirds eat to gain energy to complete the basic functions of life.
robins eat earth worms blueberries,birdseed
No, they do not.
Many birds eat the berries, including cardinals, bluebirds, jays, robins, woodpeckers, and starlings. Mammals that eat the berries include several species of bears, the white-footed mouse, and humans. Deer eat the leaves and stems. Hares and woodchucks eat the bark.
Bluebirds are larger than other birds such as sparrows and finches. They are smaller than most woodpeckers, robins, blackbirds, owls, and hawks. So they are more medium sized.
Leaves and flowers of plants
No, they do not.