While I was in Svalbard, the most common birds (apart from various seagulls) were definitely the two types of Guillemot found in Svalbard. Out of these, the ubiquitous Brunnich’s Guillemot was the most common, with the Black Guillemot being more concentrated at certain sites, but still in high numbers.
Both species were often incredibly difficult to photo. As soon as they are disturbed, they begin to take flight like the ones in the two photos but then duck down under the water after a few seconds of flying. So to take a photo, you have to be there and ready to track their flight and get it in to focus quickly. At that point, I was still learning about the settings on my camera and, more often than not, I would find that my camera would not focus on the bird or, more annoyingly, the bird has disappeared under water by the time I focused. I subsequently ended up with a lot of photos showing a small ripple in the sea, sans Guillemot.