[QUOTE 4725456, member: 9609"]No such birds here but I guess you mean Blue Tits ?
I have used 3 different size holes that will make them suitable for different species, cavity nesting type birds like holes that a tight squeeze to get into, which pretty much means larger birds can't get in and eat them or evict them.
25mm = Blue Tits / Coal Tits
28mm = Tree Sparrows, Great Tits
32mm = House Sparrows, Nut Hatches
Eviction does happen too, last year we watched a couple of blue tits having a torrid time, they first set up a nest in a 25mm hole, for some reason two House sparrows arrived and even though they could not get into the hole they stopped the blue tits using it - they then went on to establish a nest in a 28mm hole and were at the stage where she was sitting, two Great Tits arrived and evicted them and raised their own young - not sure what the Blue tits did then - Its a hard life.[/QUOTE]
We put such boxes out for these, Eastern Bluebirds, here in the States. Getting a bit uncommon, but doing better locally.