User blog comment:Lord Loss/Discussion of the Week: Cinematics/@comment-1011548-20121126194732/@comment-4212769-20121128051249

Like I said they need to be pretty desperate or intelligent (like hunting in groups) enough to do so.

They can burrow to safety, yes... but especially Barioth is an ambush predator (Rathian and Rathalos, too but to a less degree, if you want so). Rust Duramboros wouldn't really notice until the claws are in the humps. It has to be a big mistake done of the Barioth Subspecies to make itself noticeable enough for Rust Duramboros to flee.