I can describe my method of field dressing grouse, which some may like and some not.

When the bird is still warm, lay it on the ground on its back and spread the wings out. Stand on the wings as close as you can to the body. Grab the legs and give a long steady pull. The head will come right through the body and you'll be left holding the legs, skin, feathers and guts all in one piece.

Cut the wings off and rinse. Then ice.

This is a very quick method and I have no idea what birds it would work with besides partridge. And it does have a couple of downsides:

1. It removes the skin which I would prefer to leave on.
2. You lose the leg meat, but there isn't that much anyway.