Where do Blackbirds nest at night?

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I have put this under 'Life' as we do not seem to have a interest section on 'Birds and Animals' We have a blackbird which has just made its nest less than a metre away from the corner of our conservatory in some Pyracatha on the garage wall. This blackbird seems to come back every year to the same place and has about 2/3 eggs but unfortunately we have only seen the chicks fly off once. Last October we had a conservatory built and the nest is so close you can see into it from the window. Not really being a bird person my question is, that now the nest is finished the blackbird is not in it overnight so where does it go? Is anyone a bird person who can tell me?