They can easily fit out the entrance hole.
Bluebirds sometimes build more than one nest, as a diversion to predators.
They will nest in tree cavities.
Not usually, bluebirds normally nest closer to the ground than martins.
No. They make a new one for each brood but if you take out the old nest after the young have left the nest they may make a new in that birdhouse.
Wrens, bluebirds and tree swallows are the birds most commonly attracted to single-unit, enclosed bird houses. Each species prefers certain locations and habitats in which to nest and rear its young. Your welcome
Bluebirds spend much of their time foraging for food. When they have babies in the nest, they spend much of their time caring for them.
From March to June. In the south, they nest earlier, and may raise two broods.
Destroy the nest after the young have fledged. Do not, however, disturb the eggs or young of any native species, because they are protected by law. Only non native species like starlings or house sparrows can have an active nest removed.
Yes, then clean the box.
For about 8 weeks, ( 50 - 60 days ) then the young are fully fledged.
Sometimes bluebirds face competition with other birds over nesting sites. Another problem bluebirds have is a lack of natural habitat. In areas that are more developed there are less natural cavities for them to nest in.
They stay in the nest until they are ready to fly. That's why you never see baby pigeons unless you have a loft.