Never came across that before and I've heaps of boxes up, a lot safer for the brood in the hole fronted box, magpies play havoc with them nesting round the hedges here,2 broods of tree sparrows , great tit , blue tit and starlings in boxes around the house, never had coal tit nest in any ever ??
I'd be made up with the Tree Sparrows It's funny you should say Magpie, because there's a Carrion Crows nest looking down from a fir tree. It's the first time I've seen Robins in a holed box.
The funny thing about the tree sparrows is , a cock bird would always show up every spring at one of the b