How to scare away pigeons from a garden?

We've tried the old tin foil flapping in the wind trick but this has failed miserably. The pigeons are attracted to our rabbit hutch which is regularly cleaned thoroughly. Nearly every day we let our rabbit lose in the garden so he has more freedom as our garden is secure. We obviously leave his run pulled away from the cage slightly so he can go back in when he wants. However, this allows access to the pigeons and we keep finding them in his cage and also leaving droppings all over our grass. They are a pain! We can't put down any chemicals or anything because of the risk it would put our rabbit and dog in, but we don't want to harm the pigeons anyway, just want to prevent them from returning! Any ideas that are quick, easy and cheap? Thanks!