Originally posted by Urs I almost always use single point in AF try to focus on the eye and then recompose (prefocus on the tree or whatever is close)
I'm in the same camp, where the bird is stationary or not moving much. I use back button autofocus - that way your prefocus doesn't get thrown off when you press the shutter button.
Camera technology will eventually be able to detect automatically the appropriate focus point (face detection in Live View already works quite well), but for now I prefer to leave multipoint AF for birds in flight.
I sometimes use a cheat method with single point AF. Often there isn't time to move the focus point or to recompose. You focus on the eye with the pre-chosen single point (usually the centre point) and by the time you have moved the camera to recompose, the bird has moved. If there is a chance of this happening, it is often better just to shoot without recomposing and crop afterwards to get the composition you were seeking. A sensor with 20mp or more allows plenty of scope for cropping.
Here's an example. I shot RAW+jpg. Here's the jpg straight out of camera.
I focused on the eye using single point AF, centre point. The eye of the Rainbow Lorikeet is dead centre in the image. No way I would compose like this for choice.
Here's the final product after processing the RAW file and cropping to get the composition I wanted.
Of course, ideally I would have recomposed before shooting. But since I was going to have to crop the image anyway (especially as the lorikeet was looking away from the blossom), and there was plenty of scope for cropping, it didn't really matter that much. Better to get the shot with the bird in focus than take the risk of missing it while I recomposed.
Some photographers think this isn't quite Marquis of Queensberry rules, so don't tell anyone.