chirping alarm clock

Little birds wake me up every morning now, chirping and working away. One sits in the bedroom window all day, flitting away when I pull the curtain back to look, then coming back home.

They have steadily built a gigantic nest inside a crack in our window frame. This crack, it has been getting bigger and bigger:

I know we should call and have it fixed before it leaks or something, but I feel so badly for the little birds to get kicked out after they've worked so hard. I'm really not sure what to do at this point.