Greetings All.
Opinion was received from Scandinavia: The Walden Loon (based on photos only) is within the range of appearance of ARLO, but could be a COLO. Because something shy of 100% endorsement of ARLO was received, and given the overwhelming concern regarding this bird expressed on this platform and others, we (Nick Moore, John Drummond, and I) are switching our ID on eBird to Gavia sp.
Good Birding,
Steve Mlodinow, Nick Moore, John Drummond