Given this paragraph, what method of scientific study did Edmund Selous champion?

Edmund Selous started as a conventional naturalist, but developed a hatred of the killing of animals for scientific study and was a pioneer of bird-watching as a method of scientific study. He was a strong proponent of non-destructive bird-study as opposed to the collection of skins and eggs.

Edmund Selous was a pioneer of bird-watching as a method of scientific study.