Really nothing wrong with the photo, it's a result of low light, long distance and higher ISO. High ISO doesn't necessarily degrade you photos when used properly. The brighter the exposure the less degrading the noise will be. If you chose to shoot in full manual then use your exposure meter in your view finder/camera. Make sure it's in the center or adjust either your aperture or shutter speed to compensate. Nothing and I mean Nothing will improve your photographs better then Good Light. For birds, a rising sun shinning onto the subject is the absolute best. If straight over head it kills the detail and covers the subject in shadows. Light, Light, Light, it makes or breaks the photo. Also getting much closer to your subject. Doesn't matter what lens you have, the closer the better. Learn the habits of your subjects, get closer and enjoy the 2 or 3 hours of good light, then call it the day, find some other type of photography to finish the day out. If it was as easy as pointing a long lens at a bird and getting good results, then you would see a lot more quality photos on this site, takes work, attention to detail, and Good Light.