If a pawn is set to prioritize taming a creature by rightclicking the creature and selecting the option the pawn will move to gather food into their inventory if they don't already have food in their inventory. If this is the case and the pawn has to get food first the pawn will forget the prioritized action once he picked up the food and return to his normal priorities.
This is annoying, because once a task is given one usually focuses on something other, believing the task will be carried out.
Still happening in 1.0.1962.