The baby robins are still in the nest. In a way that's good. It's cold today and windy. They can snuggle together. If they were out on a branch they could be blown off. I watched carefully. I wanted to see what food was being delivered. Finally, there's an answer to the barfing. The parents are feeding them juicy worms, but mixed in with the worms are tiny twigs from the mulch that's been placed on top of our lawns, brown wood chips instead of grass seeds. It's probably the twigs that the babies can't digest.