Well, for a start, the Erdington bird is not the same as the Snow Hill one, he is looking the other way.
so maybe they changed it? Presumably they left Snow Hill after road alterations and demolitions in the early 1960's.
View attachment 138160rook
View attachment 138161carrion crow
View attachment 138162 Black penguin ad B&W penguin
I guess the yokels out in the sticks (Erdington way) were more familiar with crows and rooks. Crows not liked by farmers, but the townies would consider a penguin as they were, most likely, principally used to pigeons, starlings and sparrows at the time. Rooks are another matter.
Everyone loves penguins it seems.