"It’s just a massive animal – just really, really big,” said Renaud Joannes-Boyau, a researcher at Australia’s Southern Cross University and co-author of the study published in the journal Nature. “When food starts to be scarce, it’s so big it can’t climb trees to explore new food sources.”
Umm, can’t bears and other animals larger than 650 lbs climb trees? Weight doesn’t seem like the limiting factor for tree climbing ability.