wots wrong with our crows?

[Roz benjo]

Hi all - i'm new to this, be patient with me!
We've recently moved to a new house, in Perthshire with fantastic garden and a huge variety of birds. We've noticed that recently we are being visited by at least 2crows/rooks/jackdaws can't tell which, as they are completely bald (on the head) and look to be getting worse. They very much resemble cartoon vultures! as they have plenty of wing feathers but absolutely nothing on top and look as if the feathers on their chest are going too. Not that i'm a big fan of vultures but I would like to know whether they are sick or not, any comments would be welcome.
cheers

[Dogghound]

They are totally bald? rooks have a bald white face it isnt these is it? otherwise perhaps a deficiency, or they are being plucked by other members of their group, i.e rooks live in large communities at this time of year.

[Roz benjo]

hi yes - totally bald they really look like mini vultures, like the cartoon ones from the Jungle book. They don't look well, tho they fly ok and feed from the bird nut feeders. We're in a village in a very country area, what could they be deficient in do you think?

[Dogghound]

Not sure iv seen bald blackbirds before though. Think the reason might be that birds do moult in summer which can cause this to occur, mainly juveniles exhibit this, and in some cases the whole head of feathers can go at once.