This is the first picture that I have found in which the second female bluetit can be seen. It is the bird perching on the right hand corner of the box.
You can see a distinct difference in the plumage of the newcomer. She (the bird's sex becomes apparent later) looks much scruffier than do both Sally and Sam and I think is therefore an older bird. If it wasn't for its behaviour, I would think it was a male!
