Wildlife Photography Ethics

Encountering wild animals is an amazing experience, but in photographing (or just sightseeing) there is a certain point where you are impacting that animal by being too close, using noises to attract or disrupt it, or even (depending on the animal) using a flash.
This Code of Ethics Article sums up 11 key points to use when photographic wildlife. Some of the tips, like don't bait the animal with food, seem obvious, but others like thinking about cumulative impacts are worth thinking about.
As a potential example, this photo (winner of the 2008 National Geographic Photography award in animal behavior) looks like it was taken at night, but both animals eyes are displaying photopic (daytime) type retinas instead of scotopic (nighttime) type retinas meaning more than one flash strobe had been used. It is an awesome photo, but who knows what affects the flashes may have had on these animals?