ML619526660

Age and sex

Immature Unknown sex - 1

Behaviors

Molting

Observation details

This interesting bird was first reported by Kai Russell in the morning as a possible Yellow-billed Loon. Looking at his initial photos of it, which were backlit, I was fairly convinced that it would turn out to be a Yellow-billed. I went out to take a look at it and got this series of images later in the day. I studied the bird among other 1st-summer Common Loons, often in quite close and direct comparison. Despite it being quite different from the Common Loons in a number of ways, I convinced myself that it was just a pale extreme Common Loon, and headed home. In discussions with the Monterey Birding chat group, Sarah Lane floated the idea that this could be a hybrid, which at first I thought impossible, since I was unaware of any hybrids between these two taxa. It turns out there is a specimen at the Royal Ontario Museum of a hybrid, several other reports without evidence, and then this eBird checklist from the North Slope of AK, which clearly shows a very likely hybrid adult: https://ebird.org/checklist/S89116716?view=photos. Here's why I think a hybrid should be strongly considered for this individual: the bill shape generally is intermediate between the two species; the bill color is oddly pale for COLO; the upper edge of the culmen is only dark toward the tip (in other words, intermediate between what you’d expect for either species); it often carries its bill uptilted like a YBLO, it’s much paler overall that most COLO on this date in general including all the other 1st-summers around it; and it has notably dark "ear spots" like YBLO. I'm not sure what we could do to prove this is a hybrid without a specimen, but it sure looks intermediate phenotypically. I've shared these photos with a few others, including Michael O'Brien, who also suggested a hybrid.

Technical information

Model

Canon EOS R5

Lens

RF100-500mm F4.5-7.1 L IS USM

ISO

800

Focal length

500 mm

Flash

Flash did not fire

f-stop

f/7.1

Shutter speed

1/2500 sec

Dimensions

2500 pixels x 1500 pixels

Original file size

2.6 MB