I HAD hawks to come circling around my run mostly between around 10:00 - 12:00, then as the day got really hot, they disappeared - gone about the same time my chickens grew lazy and took siesta. Then, as the noon hour passed and the sun got lower in the sky - I would say around 3 or 4:00, they came again. That was during peak summer days. I was standing on my back porch one day and one came down and swooped about 15 to 20 feet above the run and soared back up and disappeared. Never stopped for lunch. Saw that one right after I hung some CD's from fishing line around the run and now I do not have hawks coming around regularly any more since I hung the CD's...I never saw hawks at all if it was very overcast, or storms were threatening. I never could figure out how the CD's keep them away - it has to be the flashing colored light reflecting on to the ground in crazy spinning patches, or it has to be the constant movement of the CD's as they spin in circles and maybe the hawks see themselves, the trees, the chickens, all reflected in the CD, and it disorients them. All I know is that they work, and I am at work all day, so it gives me a lot of relief to have found something that keeps them at bay. I can tell you that before I hung the CD's I was fending off many circling hawks at one time with a rake.