Blue Tots As Surrogate Parents.

[malagabob]

Further to the Robins nest I had. I suspect the chicks were predated byCrows or magpies. Leaving one unhatched egg.
I was aware Blue Tits were nesting in my boxes, and had lain the start of their clutch, So I placed the Robins egg in the nest.
Cuckoos lay in other birds nests, so why not Blue Tits fostering Robins.
I thought if one Robin hatched fed survived why not

[roopower]

It's worth a try, stranger things have happened but I wonder if the egg had got too cold to survive. Good luck.