Catcher, excellent start, did you have it on auto or manual? the second shot you took was a really difficult one, your subject(the blue tit) in in partial shade in the wood yet its really bright and sunny behind, i'm thinking that it was on auto because the camera has taken your light exposure as being the shade and has what is technically called "Blown out " (Made it too bright) the background, if you had it on manual mode you can make the decision to take your exposure up or down for whatever reason, your not relying on the camera's sensors, but these things will come to you once you under