I have a great deal of respect for photographers that specialize in in bird photography. It takes patience, research and luck. Then, there is that getting up at dawn part. If you are interested, there are several great photographers on Facebook like Nina Stavlund who produce amazing bird photos.
Of course, you need a great lens which is sharp, fast focusing and has powerful magnification. The Sigma 50-500mm f/4.5-6.3 is just such a lens. Sigma just updated this lens with a new image stabilization system with two settings (one for vertical and one for horizontal) allowing for hand-held photography even at 500mm. This lens is compatible with both a full-frame sensor and an APS-C Sensor. Of course, on the Canon 7D’s crop sensor, the high-end magnification is similar to an 800mm lens! And, it’s a zoom which makes it much easier to follow a bird and then zoom in for the close-up. Take a look at the following photos.
I plan on spending more time with this lens. It’s a blast to use!