These images were shot using a hacked Canon camera (Canon A750is). By hacking the software of the camera it is possible to use it as a motion detector. Whenever a movement (or pixel change) is detected the camera triggers. To capture birds you need good lightconditions and a fast shutterspeed.
You can read more about how to hack your Canon camera on CHDK Wiki
CHDK is implemented by installing a bit of software on your SD-card. After installing you will be provided with a complete new menu unlocking numerous new functions. Very high shutterspeeds, running scripts (and writing your own!) and camera RAW is among them.
