Remember,this was in the cycle of the appearance of IT..so Mr Hanlon saw what he saw as a fearful thing,for whatever reason it took that form for him.Why did it take the same form for Mikey as a child?Good question,because it was before his dad told him the story of the Black Spot..perhaps something in a family DNA, are they frightened by birds?Remember it seems to take forms of what scares one most,so do fears of one thing or another pass down from father to son? Who knows..but good stuff to mull over and enjoy,I noticed it as well during one of my umpteen reads of the novel..