I like the blue tit even though it is fairly dark and the background seems a little noisy (?). The yellow in the background compliments the bird amd I just feel that if you lifted the exposure there would be a danger of that yellow background blending with the yellow of the bird's underside, whereas what you have is really good seperation of bird and background, even down to the feather edges. I'm not keen on the dove. The background clashes in this case, the bird doesn't have enough space and it's posing like a startled rabbit.