A friend of mine uses a refree whistle with great sucess with his young birds especially in the early races when a batch comes over his house he blows on it and more often than not one or two come out it is good for the first races especially when the young birds are followin like lost sheep if they are used to the whistle they do react to it,
I find it a nightmare when i go round it gives me a headache but i suppose it depends on your neighbours if they will put up with a whistle blowing