In Stockton, CA (about an hour south of Sacramento) there was a similar
controversy regarding Burrowing Owls in the mid '90s. Owls had taken up
residence in abandoned gopher holes (I think it was gophers) in the center
of the race track at the county fairgrounds. A good sized population of
owls was established there. The county "planted" PVC pipes in the ground on
the edge of the fairgrounds and then blocked the ground cavities at the race
track. The owls quickly found the new "homes" and, as I recall, this proved
to be a very successful re-establishment of the colony.

Pat Quyle
at paq at rushmore.com