i spread bird seed on flat stones in my back yard. there is a pair of canada geese from a neighbors pond that i cannot discourage from staying away. using a 22 cal blank gun. dosen't work on them anymore. i chase them and they will stay 20-30 feet in front of me. they have no fear. short of death; any advice?? was thinking about a air soft gun. besides eating the birdseed they crap everywhere