Step 6: Exposure Settings
First I consider setting the camera for "spot" exposure which narrows down the area the camera considers for the exposure settings and I apply that to the area I expect the birds to occupy.
Aperture Priority should be good when shooting birds sitting still on a perch. Opening the aperture up as wide as possible (low f-stop number) will give you a shallow depth of field (blurring the background) and the fastest shutter speed (stopping small movements). The camera will be deciding on a properly programmed exposure.
I prefer Shutter Priority mode when capturing flight. The wing beat frequency of these finches I photograph must be over 20 beats per second. I find that I need a shutter speed of at least 1/1000th of a second to get a minimally exceptable shot. That is a problem.
With this camera and lens, I often find that the camera is telling me there is not enough light. This is where I push the envelope by settting the shutter speed 1 or 2 speeds faster then the meter in the camera recommends.
ISO can help. Ideally, the ISO should be set at the lowest possible number (100 on the D80). This gives you the best quality picture. Raising that number makes the light collecting sensor more sensitive and able to collect more light faster. This also raises the temperature of the sensor and introduces digital noise to the picture.
Every shoot requires me to experiment to find the exceptable balance between the available light, the shutter speed, the aperture and ISO.
Better (read more expensive) equipment can help. Newer cameras are increasingly better at low noise in low light conditions. Faster lenses let in more light.