Well it turns out that "Orange with black letters" is Newfoundland territory when it comes to banding gulls. Bruce Mactavish was all over it, like a gull to bread, and had the following information in my inbox at 9:26am ~ (less than 12 hours later! Which is even more impressive considering we slept for most of it.. Or at least, I did).
Here's the skinny:
Definitely ours, band number, 1166-00967. Banded on 30 September as a hatch year bird at Petty Harbour. So presumably a post-fledge juvenile, probably from a relatively local colony. Dave Fifield captured that bird, along with a bunch of others - it was a good day for catching apparently.
Love to know where and when it was seen, and feel free to send the capture details to the post (or put me in contact with the finder) - whatever works for you.
This is the first Ontario record we've had with the orange bands. Tons from New England, but nothing from Ontario until now.
Petty Harbour, Newfoundland!
Direct line of flight is roughly 2200km back to Waterloo! And on an interesting WSW angle too.