Found this on Alison's site just now posted by Dina. Sad news. Hope she does not mind I post it here. Just highlights the different types of challenges our peregrines face.
They went to band the 4 chicks yesterday and one of them jumped out of the box to it's death. The other died on the way to being banded, they said he was very anemic. Saw the two remaining babies napping in the nest but it's dark, they look a good size though - hope they make it. Apparently they were covered in lice and so was the nestbox. The box and chicks have both been dusted with parasite powder.