Seagulls are a highly photogenic bird, in my opinion. Their white feathers do create a challenge in exposure, though, so I find they are also a great bird to practice a getting good exposure on. I usually want to make sure none of the whites get blown out, retaining detail in the bright spots is a good sign you have picked a good exposure for the shot. The shadow detail is something I look for to, making sure the shadows can be seen but that they also retain detail will help keep the exposure balanced. I find it also really shows off their nice feathers as well, the textures and patterns look so soft and smooth.
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From @mmckinneyphoto13