why are spirit bears in danger from human ?

Answer 1

Because humans are devastating their environment without regard for their population numbers or food chain.

We do it for all other species - so why not spirit bears? :-)

Answer 2

No such bear species. The white colored fur bears of the black bear (Ursus americanus) are sometimes called spirit bears. But it is only a genetic oddity.

I can see why some fools might want to kill them. I bet the hide of a white black bear would be worth a lot. There are rules protecting black bear and there are hunting restrictions. In some areas they protect white black bears because they are a tourist draw. Really does not matter. White black bears have black black bear babies. The white fur coloring is a random genetic event.

B.C. Spirit Bear Facts
http://www.bcspiritbear.ca/more_about_spirit_bear.htm