Granted, they usually don't look all that blue. Not bluebird-blue or Indigo Bunting-blue or blue Honda Accord-blue. They are usually pretty grey. If you find a stray GBH feather, you're probably going to think, Oooh, look, a grey feather, I know I would. The bird above, which is one of them, certainly looks grey. It's a juvenile, by the way, knowable because the crown of its head is black, not white as in an adult.
Bu then look at this beauty. Artfully partially obscured by cattails, this Great Blue Heron is all the name advertizes. It's great, it's a heron, and most importantly, it's blue (ish). Click on the image -- It gets even bluisher!So now we are all clear on this. The tall grey birds are really tall blue birds.