I started the day up at Plum Island looking for a dark Gyrfalcon that had been reported yesterday. Unfortunatley, it seems like it might have been a one-day wonder. I stuck around a few hours, saw a few Snowy Owls (yep - got to make sure I keep tabs on them for Patrick, Corey, Quintus, and Nathan), all three scoters & several Long-tailed Ducks, but when it started raining, I decided to head over to Cape Ann and see what I could find out there. I tried a few shots at the spot where a drake King Eider has been spotted in the last week (same place as the last few years) in Gloucester but dipped on that too. The rain continued so I decided that I would head to the fish pier and force myself to study gulls a bit. I was rewarded with 7 species of gull with the highlight being a first winter Black-headed Gull.
Flying around in the same area as the Black-headed Gull was a smaller Bonaparts Gull which was nice for comparison. Also nice for comparison were a few Iceland Gulls and a single Glaucous Gull. There is a size difference between the two, but I find that I have a hard time seeing that difference in the field, unless they are side-by-side. The Glaucous does look heavier, and maybe it's just me, but it seems like the larger Glaucous has it's center of gravity closer to the front of it's body. I find the best field mark for distinguishing the two is the shape of the head. The heads on the Iceland Gulls really are rounder looking compared to the sloping head of the Glaucous Gulls.
Now, can you tell which is which?
