In a rare shot, I have managed to get a bridled Common Murre, an unbridled Common Murre, a Thick-billed Murre, and Razorbills all together. There are small differences between the Common Murre and the Thick-billed Murre, making it very difficult to make the identity "on the fly." In this picture the Thick-billed Murre is standing to the left of the four murre on the second shelf. Note the white peak at the top of the breast extending into the neckline. Also note the thicker bill compared to the others. Click to enlarge the image to see it better.
When viewing the Murre (turr, as these birds are often referred to in NL) in bright light, it is very difficult to be sure if the while line along the gape is really a white line of if it is a reflection off the dark bill. In this shot there appear to be three birds with a white line along the beak. At least one appears to have a sharper peak of white on the throat, but is it just the way the bird is standing? The beak of the Thick-billed gull is slightly thicker, but that is also tricky to determine as each of the birds is standing at a slightly different angle. The other identifier is that the Thick-billed Murre has a blacker head while the Common Murre's head shows browner. With all of these things considered, I think the bird on the left with its head bent down may be the only Thick-billed Murre in this shot.
For me, viewing the birds from the back makes the identification even more difficult. Two birds show a bit of a white gape line, but I think that is a reflection. I have looked closely at the beaks and see none that are thicker. I am guessing there are no Thick-bills in this shot.
This shot is a little more interesting as it was taken in the shade. Posture accounts for the difference in the white breast line. The bridled bird shows with a clean division between the white and the black on the breast while the other Common Murre in the shot show some peak. The second bird from the right seems to have a hint of a white gape line and the peak of white seems to go higher. However, it is very difficult for me to be sure because the neck is stretched upward.
Then, there is this group picture that really show more of what it is like to see Murre in their natural environment. They are crowded together and in constant motion. In this shot (be sure to enlarge), I can call with confidence at least one Thick-billed Murre. I also see two other possibilities. How about you? How many can you see?
Amidst all of the hard work of learning to id these very similar birds, I look at this shot and am reminded that watching birds is not ALL about making an identification. It really is about the enjoyment of a single bird that engenders endearment.