What killed the baby robins?!

Hello, I was hoping someone might be able to help us identify what might have predated the baby robins from a nest box in our garden. The nest box is on the wall of our house, about 5ft off the ground and behind a spiky pyracantha bush which is growing against the house. It is used every year by robins. Today I found these remains on the ground near the nest box. Two of the bits of remains look like they might have been partially digested and coughed up again? We don't have many cats visiting the garden but they are seen occasionally, as are squirrels and magpies. Our neighbour has had a fox visit her garden recently. I'd appreciate any ideas on who the culprit might have been. Many thanks

  • How sad. They look close to fledging. I would suggest a cat. I believe that cats do not like the taste of Robins and will vomit them back up. Doesn't stop them from chasing them though.

    Unicum arbustum haud alit duos erithacos

    (One bush does not shelter two Robins)

    Zenodotus (3rd Century B.C.)

     

  • Thank you for your reply. That's interesting about cats not liking the taste of robins - I did not know that. It does look as though something has vomited them back up. I don't know how many babies were in there but there are none left. It seems to be a fairly unlucky site for the robins. Last year a sparrowhawk took one of the parents using the same nest box so the other parent was left to rear eight babies on its own. Fortunately it was only a week before they all fledged but the remaining parent was looking bedraggled and exhausted by then. Do you think I should clean out the nest box and put it back up, maybe higher up, to deter any further predation? I was thinking I could also surround the area with spiky branches too. The nest box is currently situated behind a pyracantha which I thought would deter most things but it obviously wasn't enough this time.