Oh dear... I have been looking at these birds the whole day and just now noticed that the second bird has one leg... How could I miss that? Probably because I was so excited when I found just perfect words in my little antique book for the branch... I don't think that I can add the leg now because I used a glass-like finish on that part of the collage (the bird has a completely different feel). Can it be a one-legged bird?
They are resting their little wings on etsy: here and here.