A little something about how shots like these are taken…at first glance, you might think I used a flash at night. No, I don’t use a flash on wildlife. I try to disturb the subjects as little as possible, and so never use a flash. This shot was taken during daylight hours.
Modern cameras have a built-in light meter. Some have ways that you can adjust how the scene is metered. Instead of using the standard method of measuring the light from the entire area of the scene, in shots like this “spot” metering (Nikon’s version) measures a small area of the subject, and tells me what settings I should use to properly exposure that area.
This method of metering is especially helpful on white subjects. The white area is exposed properly, and the rest of the scene is then under-exposed. In normal metering mode, white birds are often over-exposed (blown-out) as the meter is averaging the entire area of the frame. I was continuously frustrated over my inability to take good pictures of white birds until I learned about spot metering.
Now, I use spot metering 90% of the time for bird photography. Most of my interest lies in bird portrait images, and so exposure of the rest of the scene is not as important to me.
Notice the effect is not as dramatic on this Night Heron image. Obviously, the bird is not as white and so, while the subject is exposed properly, the difference between it and the background is not so much.