My Tenant bought 3 birds just before Christmas and I bought her a new coop as a Christmas present. They were fine yesterday EXCEPT I did notice there were some yellow foamy droppings around (rather like beaten/foamed egg yolk. This morning Rose (her Magpie?) is almost dead, unconscious and barely breathing. She couldn't bear to pull her neck so has put her indoors. I had gone to work and had this recounted with a shocked phone call.
From her description (she is a nurse) I expect Rose to be dead tonight but she was eating and fine last night.
My other tenant had 2 of my chickens in about October and, again, they were found dead overnight. (a bit confusing but I have a granny annexe and small bungalow on my smallholding I rent out, so two sets of tenants, 2 different coops, two different parts of the property)
That's 3 rapid unexplained deaths in birds but my flock are all fine.
What could knock a healthy bird over overnight without prior symptoms?