SX50 bird fiasco. Help.

i believe the shutter speed is slow enough to have contributed to the poor quality of the first photo.  IS can only do so much before you need to rely on a tripod for still subjects or shutter speed for moving subjects.

My use of P mode leads me to believe that P mode allows the camera to pick the best settings for a most-still subject with a mostly-still camera.  The camera doesn't know if you or the subject or the camera are moving a lot or a little ... even with IS helping.

If you're expecting to max out your zoom for moving subjects in bright daylight, I would leave the camera on Tv with a shutter speed faster than 1/600s (the faster the better) with IS on and auto ISO.  Tracking AF might help ... read your manual.
Good luck ...