From what I understand, they are pretty handicapped on free range due to the top knots and also they seem to lack the survival instincts necessary to be flighty, though the Polish may be more attuned to being flighty than the silkie. Then, for the silkie, is the lack of flight...a chicken wanting more speed of escape will often use their wings to get some acceleration going. Feathered feet create drag against the grass while running and this too can make them slower.
Maybe if they were started out young along with other breeds known for being flighty on free range, they might be able to learn to have some survival skills when it comes to ranging, along with keeping their crests and feet trimmed of fur and feather...that would be a cool experiment for someone to try and see if they can make silkies into free ranging birds.
Maybe if they were started out young along with other breeds known for being flighty on free range, they might be able to learn to have some survival skills when it comes to ranging, along with keeping their crests and feet trimmed of fur and feather...that would be a cool experiment for someone to try and see if they can make silkies into free ranging birds.