The orc pack didn't stick around for long after Beorn made an appearance. They knew of the skinchanger and knew they would not get past him, so quickly retreated away to regroup and plan again. Beorn's attention was now completely on the group as he chased them down. As far as he was concerned, they were all intruders just like the orcs.

The dwarves fled as quickly as they could across the field, glancing back towards Serena.
"What are you doing, RUN you fool!" Thorin hollered back at her. "You can't seriously think you can fight that thing?!"