I only see Common Goldeneyes in northern Utah during their nonbreeding season because they breed well north of here so I get a touch excited when they show up at my local pond.
Four days ago I was able to photograph a Snowy Egret landing sequence that I liked because of the action of the bird, the setting and the lovely lighting I had at the time.
Yesterday the "unexpected" bird was a juvenile Osprey in the Wasatch Mountains. I'd say it was unexpected because I'd been photographing songbirds and wasn't expecting to see North America's "Fish Hawk" in the same area.
I was photographing birds when I spotted a hairstreak butterfly land right in front of me and took some images of it, I didn't know at the time it was a Colorado Hairstreak butterfly, I found that out later after I got home.