Hey there, grouse shots! Another good tip for foxes is to make a sound like an injured prey animal....
A distressed squeaking rodent, and squealing rabbit... Putting your lips against the back of your hand and making a kissy type noise while sucking. You can buy whistles online that simulate the noises quiet well, they are hunting whistles, but that is irrelevant to their effectiveness....

The foxes will hear the sound and come running thinking they are in for a free feed... If you whistle from a down wind position you can call them in close enough that you could fill the frame with a nifty 50.. Of course, if they get a wiff of you, they're gone...