Eventually, he could no longer see any magical beasts in sight, and while the concentration of mana began to diminish, the beasts there seemed to have left the area due to low mana, Ainz looked around for a bit and soon found a small inhabited by a few snakes, the place as quite hidden, without any holes.
So he simply cleared the cave, and chose to rest in the place.
Ainz rested for half a day.
After which he woke up, ate another of the beast jerky, and thought about the previous event with the magical beats.
He was quite disappointed that he wasted such an opportunity to kill both magical beasts, but at the same time, he felt a little relieved because he briefly sensed an existence he could not handle at the moment would have awakened if he did, especially after his senses screamed at him.