After more analysis and discussion with others, I'd like to correct a mistake I made on this blog last week. I labeled a mostly black-headed murre from offshore Cape May County waters as a Thick-billed Murre when instead it was actually a Common. Some things that are more consistent with Common Murre include bill shape, the shape of the hood/ chest boundary, a bit of white behind the eye, and flank streaking. While this bird was the only dark-headed murre we saw that day (out of 27 total murres), a few more days at sea this week have revealed lots of molting Common Murres (and even some in almost full alternate plumage). Given what I've seen over the last few weeks, which has increased my experience with Common Murre in the mid-Atlantic quite a bit, I think we might have a bit more to learn and explore in trying to accurately resolve the status and distribution of these two species. A few things seem clear - Thick-billed Murre is the much more likely species to be seen from shore in the northeastern US in winter (though any murre is rare), and Common Murre is relatively much more common in a strip of water between 5 and 20 miles offshore (at least from Long Island south through the mid-Atlantic) during the same period. It seems important to be extra careful when reporting the [seemingly much rarer here] Thick-billed Murre from inshore waters off of New Jersey. Along these lines, here's a photo that I took on Saturday off of Belmar, NJ of a molting Common Murre:
At a glance we can tell that this is a large alcid by the body bulk and wing shape. We can get to murre over Razorbill by the pointy front end, the blunt rear end, obvious feet in flight, and dusky "wingpits". One thing that I've noticed recently is that murres consistently tend to have lumpy body shapes, especially when they have their wings raised in flight; Razorbills seem to have smoother contours to the bellyline, though they can definitely carry more weight toward the rear of the body, imparting a bit of a murre-like potbelly. This particular bird can be identified as a Common Murre because of the white pattern in the face including some feathers above and behind the eye (vestiges of the distinctive basic plumage), the slim, pointed bill, and the dark flank striping (or, as Tony Leukering might say - it's a Common Murre because it hatched from a Common Murre egg).