Harlequins are always a great find! Interesting that there has been at least one Harlequin reported at Sam's or within a short range of the park for the last 3 winters. Makes you wonder if it's the same bird returning. Your sighting may be the first of the season for the park - haven't seen it reported on ebird or Ontbirds yet. If you see it again you may wish to report it to Ontbirds since many other birders would be interested. Love that last shot - looks like he's yelling at someone.
-kris
edit: Looks like a large OFO group relocated the Harlequin on Sunday - lots of ebird reports coming in.