A S7 Sibir Airlines Airbus A320-200N, registration VQ-BRI performing flight S7-5219 from Novosibirsk to Magadan (Russia), was on final approach to Magadan's runway 10 when the crew initiated a go around from about 500 feet AGL after a bear was observed on the runway. The aircraft positioned for another approach to runway 10 and landed safely about 20 minutes after the go around.