@Sam: Thanks for the response - I wasn't intending to imply that they'd been deliberately moved, I was just trying to find out what might have happened. It might be that there is a bug in the gallery which caused this ? As long as they'll be considered for the "Animal" mission then I'm happy
@skyblue: I hadn't noticed that until you'd mentioned it - maybe there is a bug in the gallery where it is only storing images within the previous 5 days. A bit of a problem when the missions last longer than 5 days ...