In New Zealand slang, "box of birds" means you are feeling well and happy. It's an expression to answer the question "How are you?". After reading this book, that expression is a bit ruined for me now!
The main character, Malorie, finds herself pregnant just as the world comes to an end. The end starts with mysterious acts of brutality and suicide becoming more and more common over the world. The one thing that links them is that people see something that turns them violently insane. The book covers two time periods, when Melorie enters a safe house set up for survivors, and 4 years later with two children "boy" and "girl", that she is caring for by herself. The premise is terrifying, and had me thinking of The Happening, The Others & the Dr Who episode Blink. Some aspects stretched my suspension of disbelief to breaking point, power is on, with the blasé explanation it's hydro so it works all the time, & telephones still work. Without power, it'd have made the world a lot harder to live in as they could never look outside, and inside had to be completely cut off with blankets on the windows (hello, did they not have curtains? Would blankets be much better then secure curtains?)
Well written and full of suspense, Box of birds is worth it if you overlook a few flaws.