The landing bird may appear to be attempting the assassination of the perched bird, but the she was simply landing on an awkwardly small perch. The two were clearly part of a family unit.
Yes, those are Ospreys perched on lawn chairs in the background. The extreme storms of the last few years have left a few odd deposits of deck furniture miles away from any homes. There's even a gas grill wedged two-thirds into the mud out there.
To get all these shots, I carry the camera in a drybag that I keep under the spray deck of the kayak. When I see a potential opportunity, I pop the deck, pull the camera out of the bag, take off the lens cap, turn it on, and start shooting. It's incredibly difficult to do all of that quickly, especially since I don't want to slip and throw my camera equipment into the river. That means that a bird that appears quickly and then disappears quickly is very difficult to shoot effectively.
Fortunately, when the loon came around the bend, I already had the camera out to shoot the Ospreys on their lawn chairs, so I was able to focus on the loon and twist to follow the flightpath, simultaneously contorting my body into a pose worthy of a kayak yoga video and grabbing my favorite shot of the day in the process.