Starling nest

Thanks all! unfortunately I don't have cameras in the other two boxes so not quite sure what is happening with those but there are definitely nests in them, as for the smashed egg I did read about starlings being brood parasites so it is likely due to the lack of nest space here another female laid an egg in the tree box and took one out so it all adds up! can't be sure of course without witnessing it, we do get wood mice and have seen the occasional rat but very rarely get squirrels here in the garden, may have seen one in the 5 years we have been here but for some reason they just don't come into the gardens, although I often see them in the playing fields just round the corner!