There is a world somewhere between reality and fiction. Although ignored by many, it is very real and so are those living in it. This forum is about the natural world. Here, wild animals will be heard and respected. The forum offers a glimpse into an unknown world as well as a room with a view on the present and the future. Anyone able to speak on behalf of those living in the emerald forest and the deep blue sea is invited to join.
My hypothesis on why Brown bears do better in Captivity compared to Polar bears has to do with available diet,
I would assume that it would be very costly for a zoo or sanctuary to keep fresh blubber and meat for a Polar bear as well as being able to find the right type of animal's that polar bears actually prey on. I doubt that many zoos carry beluga and Walrus meat and blubber, while Brown bears are omnivores and will do well on a diet of many different types of meat and fruits and veggies.
Like Bengals who were kept in captivity and malnourished until recently in India, I think that they may have been able to obtain larger sizes if they were actually given proper nutrient rich diets and enough fresh meat which seems to be occurring more frequently in India now a days.
Even that captive bengal that was caught as a wild cub looks to be plenty hefty and large while he was captive.