Expert: Roger Lederer - 6/1/2010

Question
We have a weekend house in PA, and found a robin's nest on our Christmas wreath, by the front door, under a porch.  I spotted 4 to 5 blue eggs, did not touch them, and returned the wreath to its spot.  A week later, we returned to find 5 dead baby robins scattered about by the front door.  One was plump, 3 were thinner, and one was scrawny.  I also found 4 new eggs in the nest, and but no egg shells.  A few weeks later, we returned to find 3 healthy baby birds in the nest.  My question, did the mother discard the babies thinking they were not viable, or was she in need of laying more eggs and required room for the new baby birds?  Or was it possible that she was not the one who was responsible for the death of those baby birds?

Answer
The mother bird was not responsible for the removal and death of the first clutch of birds. It was almost certainly a predator - cat, rat, jay, squirrel, or something similar. The predator just didn't finish what it was doing. Or maybe there was a heavy wind that blew the wreath around and dumped the nest. The mother then renested and laid another clutch of eggs.