The Sun Bear is the world's smallest bear, but it is also the bear at greatest risk of extinction. The Sun Bear lives in south east asia, but habitat loss has seen Sun Bear numbers decline by 30% in the last 30 years.
The BBC and the Guardian both have reports on the problems faced by the Sun Bear and other bears:
Concern grows for smallest bear (Sun Bear picture from here)
More bear species threatened with extinction
The Guardian also has a gallery in which the survival prospects of various bear species are discussed: Bears under threat