if you have a tall solid fence, such as a wooden fence, you could run
a single "hot wire" around the top of the fence to keep the cats from
jumping up onto the fence and into your yard.

Deborah Wisti-Peterson email:nyneve at u.washington.edu
Department of Zoology, University of Washington, Seattle, Wash, USA
Visit me on the web: http://weber.u.washington.edu/~nyneve/
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