After months with no sign of activity in our birdbox we have a new visitor, here in the UK it's starting to get cold as we move from late Summer and into Winter, I have previously been told it's not advisable to have over-wintering Blue Tits roosting as these can disrupt Spring nesting. Should I plug up the box till the Spring? any advice please as I don't want to loose next years clutch (we lost all 9 chicks this year).