Sony NEX-5 with Leica APO Telyt-R 400mm f/2.8
If you want an easy to handle 600mm equivalent focal length camera setup try the Leica APO Telyt-R 400mm f/2.8 with the Sony NEX-5 since the lens actually has a handle. A lens adapter is used from the Leica-R lens mount to the Sony's E-mount. Also to ensure you can hear the birds in the video try the ECM-SST1 Compact Stereo Microphone for the NEX.
Thanks Khun K!