Answer:

We can see a bird with a fairly long neck, long legs sticking out from beyond the tail, and a fairly long bill. The upperparts are a dark gray and the underparts are white. This color pattern may recall a shearwater, but the legs and neck are far too long for shearwaters. Likewise, alcids have much shorter necks and are much chunkier overall, contrasting with the streamlined body of this bird. We can also see the upturned primaries of the far wing––alcids and shearwaters tend to fly with very straight, stiff wings without much curvature.

Really only one family matches the shape and color pattern of this bird––loons. Five species of loons have been recorded in California, with three being regular visitors––Common Loon, Pacific Loon, and Red-throated Loon. A good place to start with any loon is the bill. We can see that the bill is rather thin, and the lower mandible is upturned and meets the upper mandible to form a sharp point. This is consistent with Red-throated Loon, and the other loon species will generally have thicker bill, lacking the upturned structure. Common Loons in particular have massive bills that would appear over twice the thickness of the bill shown by this bird.

However, we are fortunate that we have a frozen image where we can examine the bill size and shape as long as we wish. In reality, this bird would be flying past us, and would only be in view for a few seconds before disappearing. Gauging the precise size and shape of the bill is extremely difficult in just a few seconds on a moving bird, especially because bill size and shape aren’t that different between Red-throated Loon and Pacific Loon. Therefore, it is important to understand the other reasons this bird may be a Red-throated Loon.

Looking at the head/neck pattern, we can see that the head and neck are mostly white, except for a dark gray crown and hindneck. This dark gray area almost pierces the eye in half and appears like a straight line from the bill to the back of the neck. This pattern is again consistent with Red-throated Loon, although it is worth noting that Red-throated Loons can be incredibly variable in regards to head/ neck pattern. Most importantly, it is unlike the head/neck pattern of Pacific Loons, which are much less variable. A Pacific Loon has a mostly dark neck, which gives the impression of an isolated white chin and throat (see the image of a Pacific Loon below).

There are a few other things to note. First, note the overall grayish or silvery tones to the upperparts. Pacific Loons and Common Loons tend to be darker in color, with their upperparts appearing blackish or brownish-tinged. Finally, note the location and date. The photo was taken on February 18 in Humboldt County, California. February is a month you’d expect Red-throated Loons and Common Loons to be abundant throughout the coast of California. Pacific Loons, on the other hand, are uncommon in winter in California, and don’t really start their spring migration until March. So the date and location alone can give you a starting point as to which loon species you might be seeing.

This Red-throated Loon quiz bird was photographed by Frank Fabbro.

Congratulations to Thomas, Pete, Ben, Riley, Calvin, and Henry M. for getting Red-throated Loon!