ISO1600 is going to be noisy. Lots of good detail though, just mask the bird and use a bit of NR on the rest of the frame. Nice shot. Only nit-pick is the fence perch.
Erik Williams
Olympus E3, E510
12-60 SWD, 50-200 SWD, 50 f/2 macro, EX25, FL36's and an FL50r.
For non-landscape N/W shooting, you should keep ISO and shutter speed at the top of your consideration. Shutter speed only just high enough to do the job (no overkill) and the ISO as low as possible. The aperture I typically keep stopped down just 1 stop or so (for small birds) so I usually don't change it too often throughout the day.
Learn to use manual exposure controls to fully understand how and when to make these changes. The understanding will help you when using auto modes as well.