Bonaparte's Gull

I decided several months ago that cloudy weather wasn't going to stop me from taking pictures of birds. You often end up with less than ideal photos, but you sometimes get some great ones (soft lighting has its advantages). And besides, when you live in the Pacific Northwest, you'd be missing a lot of days if you waited for sunlight, especially in the Winter.
Such was the case this past Sunday. A cloudy, foggy, gloomy, misty day. But I was able to get some pictures of a new life bird; the Bonaparte's Gull seen above. This was an especially bad day, but I've found that if I underexpose by as much as a full stop that I gain a couple of advantages. One, I gain a stop in shutter speed which helps with focus. And two, my camera's metering system tends to overexpose in these lighting conditions. The pictures will turn out somewhat dark, but that can be corrected in post. The pictures still aren't as good as they would be with full sunlight, but usable.
The top image is of an adult and a 1st Winter Bonaparte's. The adult is in the lead and is determined by the white outer primaries and white tail. The trailing 1st Winter is determined by the dark outer primaries, dark patches on upper wing and black tips on its tail feathers. This is one gull that is fairly easy to identify, however I briefly thought it might be a Black-headed Gull which would have been very cool as it is very rare, but its reddish bill and dark under wings did not match this bird.