This yellow colour looks actually very tick-like to me... that's why I immediately thought it could be one!
If it is a tick, that would at least not be very worrying : it will eventually fall off on his own when its belly is full...
(Let's just hope it would not take too long, because your poor hen deserves to be able to breath easily and normally...)
But I would be you, I would put some vinegar on a Q-tip (is it really the word?), and I would put it on this growth for one good minute. To at least see how it reacts...
If it is a tick, that would at least not be very worrying : it will eventually fall off on his own when its belly is full...
(Let's just hope it would not take too long, because your poor hen deserves to be able to breath easily and normally...)
But I would be you, I would put some vinegar on a Q-tip (is it really the word?), and I would put it on this growth for one good minute. To at least see how it reacts...