The whole assembly didn't last more than 15 minutes. More and more came as they moved across the lawn; then they all took flight toward the blue patch of sky in this photo. Horizontal lines on far trees are reflections caused by photographing through windows. If I had opened the door, or gone out on the porch, they would have flown at once. I've only seen this once before. That time, instead of moving beside the house, they came in a flood over it and headed south, not west.