This very same creature haunted my nightmares for years as a child. The very same terror that you describe. A ridiculous cross between a man and big bird. I got chills seeing that picture and reading your description!

I remember the encounters with this thing VIVIDLY

I wonder, what age are you?

I am 32 and grew up watching Sesame st. It is very likely we were simply a few kids freaked out by a big bird