The first time I saw it I was alerted by a soft whistle I hadn't heard before. When I finally found the source of the sound, there was the Gray Jay.
It's hard to describe them. They glide down from the trees so silently you don't know they're coming, they don't shriek like the Blue Jays, they're not agressive or scrappy. They are big, gray, soft, fluffy, friendly, quiet birds that inspire a sense of awe when they stop by to sneak a bit of your food. You are so amazed by their presence, that you don't even mind, in fact you'll gladly hand it over just for another appearance.