Hi Izzie,
Just to advise not to be shy about using higher iso's on birds in bright light, oftentimes very much needed! One of the first exercises Joe gave me to practice with birds in flight was to set my camera to Manual f/8 SS 1/2500 Auto ISO set to 3200... While some shots were too, noisy most every shot was sharp so I learned a lot from that exercise. Another very valuable lesson for me was Mike's advice to always check my exposure by checking my histogram which I do religiously. And today I'm trying to be very conscientious of my backgrounds (a distracting background blurred is still distracting), being at the same level of the subject or lower, and being aware of where the light is falling on the bird.
For birds I typically use manual, choosing my shutter speed and aperture and auto ISO typically set to a max of 800. Then I try a few test shots on my subject and I can see right away if the light will allow for a proper exposure, first thing. Then it is simply a matter of deciding if I can get away with a slower shutter speed/larger aperture or if I have to up the ISO, or if the lighting conditions are impossible for a quality shot. Easier for me than in manual mode because I typically have a set aperture in mind/or the lighting conditions dictate the aperture, so it is simply a matter of changing the shutter speed.
When I check out my bird images I view the eye at 100%, and it is super easy to see when I just missed my focus which typically happens when I'm using slower shutter speeds to avoid using a higher ISO. (hand held, longer focal lengths)Try photographing a bird in your yard at various shutter speeds and check out the difference.
If you view Barbara's bird images you'll see that they head of the bird/eye is always beautifully sharp. And check out the ISO's used by Bobo and Joe, all beautiful!
PS
Great info on chosen SS and focal length (greater for cropped frame cameras)
https://www.cambridgeincolour.com/tu...era-lenses.htm