I am a little late posting this because it happened a couple of weeks ago - just no time to post.
I realise that nature can be cruel but sometimes I find it hard to take. I posted a few weeks ago about the blue tits nesting in the box in our pergola. The box is just outside my office window and I heard tapping. It was a Great Spotted Woodpecker hammering away trying to get into the box. It was after the babies.
I kept chasing it away but it kept returning time and time again. Finally, it found a crack in the bottom of the box and started pulling out moss, part of the nest. I took a photo of it when it reached one of the babies - blood all over its beak :(
I realised that I had to do more to save them, but I did not want to interfere with the box too much otherwise the parents might abandon them. So, I stuck a piece of plastic over the crack and secured it with masking tape. I could feel movements in the box so some of the babies were still alive.
The GSW still kept coming back but luckily did not manage to hurt any more babies.
Mr & Mrs Blue Tit still continued to feed the remaining chicks until they finally fledged.
I will post a link to the photo I took but I prefer not to display directly in this post because I find it distressing.