Date: 11/21/18 5:23 pm From: Wayne Hoffman <whoffman...> Subject: [obol] More on Yellow-billed Loon
Now that I am seeing the photos on my laptop rather than phone, i have a couple of comments.
1. Most of the Yellow-bills I have seen in Oregon in the past were immatures, but this bird is an adult, (or SY?) and has not completed molt out of alternate plumage, hence the dark head and the white and dark pattern of the throat. The lack of back spotting suggests these feather have already been replaced (different sequence vs head than Common Loon) or else may indicate it is a second-year bird whose first alternate (summer) plumage lacked the spots.
2. My experience with previous Yellow-bills in Oregon estuaries has been that they had much larger home ranges than Common Loons, and would range distances of up to a few miles daily. I recall seeing the one Alan referenced from Florence off the public docks, then less than an hour later down almost to the jetties.
3. Alan is correct that Yellow-bills are more likely to spend time in estuaries here than Pacifics do. We do have a few Red-throats regularly in our estuaries although most winter off the beaches. Back in 1979-81 I did a lot of aerial survey work off Florida, Texas,and Louisiana. In winter, Common Loons were easy to see in the estuaries in those states, but from the survey planes we saw them out on the Gulf of Mexico regularly to 20 miles offshore, and occasionally to 60 miles. At those distances the water was still shallow enough that the Loons could easily dive to the bottom. Inshore they were feeding mainly on crabs, and I suspect they were offshore as well, although we were never able to get much info on food from a plan traveling at 80+ knots.