Surely not the appropriate scientific name. But really, a shocker to capture a Pacific Loon in Denver any time of year. I heard reports and was able to see it for myself. Believe this is a non-breeding plumage specimen (?).
First go with the 2.0x and shot in crop mode as well.
Feedback welcome as always; tried to process as close to taxonomical images I've seen on the web since I've never seen a Loon in person.
Canon R5
600mm + 2.0x
Handheld
ISO 1250
1/800
f8
LR and PS, DN. Touched two tiny spots in water.