Actually they are straw sculptures on the top of a thatched roof.
Hundreds of years ago they were put there to ward off evil spirits, and some say they were to prevent witches on broomsticks from landing on the roof! Nowadays they are purely decorative. Mind you... I haven't seen many witches around these parts.....
Thanks Maggiemae. These ones are covered in chicken wire, tho not all of them are. They are attached to the roof by a long wooden stake which is dug into the thatch of the roof. @maggiemae