Magpies and crows.

We have a lovely big mature tree at the bottom of our garden. We used to put bird feeders up and had a host of visitors from blue tits , robins , finches and sparrows to starlings , racing pigeons and doves. 3 years ago we stopped putting feeders out as we spotted a rat feeding out of one of them. Around the same time a couple of magpies started building a massive nest. 
we’ve never had a lot of birds back in the garden and not sure if that is due to the magpies or not having feeders out.  We’ve seen them have a few clutches and the young magpies stay around for a while. I’ve counted 6 in the tree in autumn.  Sometimes they come and sit on the fence and look in the window.  They don’t seem too bothered about us or our 2 dogs. 
today we spotted 2 crows in their nest while they sat close by watching. Very sad really as that nest took them a while and they’ve lived there for years. Are they likely to get it back ?  Feel quite sorry for them.  Thought they were all part of same family too.  These crows are massive. They don’t look like Jack daws.