Life on the Outer Coast

I've been counting birds on my commute between island and Crescent harbor again this fall and winter. It took awhile for me to get motivated this fall as there just weren't that many birds to count in September. I've been fairly faithful about counting since early October, keeping the data in a daily calendar instead of a spread sheet. The data entry will no doubt be great fun.

For at least a month now, I've been seeing birds that I couldn't quite make up my mind about. They were definitely alcids of some sort, just hadn't a good enough look at to decide which one. At first they reminded me of guillemots, just lacking the white wing patch. Some sort of murre made the most sense based on the features I could see. Given that winter Common murres have a distinctive black line on their cheek and winter Thick billed murres have a mostly black head, I decided that the mystery birds were most likely winter Thick-billed murres. I saw or thought I saw white on the chest so decided that these birds weren't in breeding plummage.
This last week, I've managed to get close enough to get a few photographs. I'm not sure about all of the birds I've seen the last month, but the birds in the photo seem to be Common murres in breeding plumage. The bill is thick, but doesn't seem to be the quite the right shape, the flanks are streaked and I'd be hard pressed to describe this bird as blockier than the rest of the Common murres that I've seen.
About half the birds I'm currently seeing on the commute are clearly winter plumage Common murres and the other half the same species in breeding plumage or possibly Thick-billed in some cases. Given that the birds reminded me of guillemots (all black chest) it might be safe to assume that most of the birds were breeding Common murres. Hard to say for certain though.
Now I'm pretty curious about the timing of plumage change in murres. Does it start this early most years or is it pretty variable? Guess I should add notes about plumage in the future.