Birds are wonderful creatures, some of them are so beautiful. They range from tiny Fairy Wrens and finches to the very large Eagles, together with the giant Cassowaries and Emus. There is also such a large range in the colours of birds.
In order to capture birds on your camera you need very long lenses generally 300mm or more, I really prefer 500mm and I love the Nikon 200-500mm f/5.6E ED VR AF-S lens now for the majority of my bird photography. Shorter lenses can be used if you select a spot where birds frequent on a regular basis and use a remote shutter release, I have had some success with this method but it is rather hit or miss.