I was out fishing the smith river east of a rural town ULM Montana. It was approx. 4:30 pm when I noticed what looked like a flock of many birds traveling south west over the Lewis and Clark National Forest. I assumed they were Canadian Geese but these type birds don't climb that high in the sky especially just below clouds! I then though....these are some type of lights and were moving fast going in the southernly direction toward Helena. They were initially clumped together and started spreading out, then disappeared behind the clouds. This sighting lasted about 20 seconds, very unusual.