Can anyone suggest a low growing plant to deter pigeons?

Hi, my bird feeder is in a prime spot where I can see it from the conservatory. Despite using no mess bird food there is always a pigeon or two waddling around underneath it trampling anything I attempt to grow. Can anyone suggest a low growing evergreen prickly plant that I can plant round it. Preferably, but not essentially something that smaller birds can hop through/under. Thankyou.