"William L. Rose" wrote:

Just my 2¢, but I hope your ready for the dead birds. The voltage (It's
really the amperage you need to be concerned with.) that will put bambi
on his butt is gonna' fry "tweety bird" and friends (four and two
legged) that come into contact with it. You may be down with the
collateral damage but passer-bys, neighbors, grand kids, ect., may see
you in a whole, brand new light. Birds also help clean up insects in the
garden, so think about unintended consequences.

Haven't you ever seen birds on power lines? The voltage and ampreage
are a heck of a lot more than electric fences.

Here is a place where you can read how the fences work.:
http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex611