Ive noticed a large number of the corvids visiting my garden are all loosing significant feathers on their heads. A few of the jackdaws are almost completely bald, magpies mainly round their eyes and this morning I've noticed one of the pair of big crows os begining to lose them now too? None of the other birds that visit show the same problem and ive never noticed this before? Is there somthing they are lacking I cab add to their feed?
This could be just moulting, perhaps? Corvids moult and change their feathers at this time of year, which can make them look patchy and somewhat bald. If they're otherwise okay, it might just be that? Otherwise it could be mites, but I'm not sure what you can do beyond cleaning feeders and keeping the feeding areas in general clean.