Dogs are very effective! Our chickens have a lot of predators - foxes, coyotes, hawks, and bobcats. Since getting Pyrenees many years ago, we haven’t lost one bird to them.
I have a Great Pyrenees on my property. He is on patrol 24/7 and loves his job. Early one morning I saw him actually run down a Coyote, grab the predators hind quarter on a full run, and literally throw him in the air about 25 feet over a fence. Haven't heard or seen one Coyote yelling at night or in the early morning since that incident. My Pry is a three year old, a mere 126 lbs., and runs like a small horse. He is also very alert to large birds that fly over the property.