I'm not an attorney but....

This would be covered under local ordinances and so would be different
for everyone. You cannot say that since you cannot control wildlife you
aren't responsible. Townships protect the rights of their citizens
and the values of their houses. If you create a public nuance or do
something to lower the value of surrounding homes then most certainly
the township would sue you under some ordnance (or enact one if you
****ed them off). Imagine if I left a rotting cow in my back yard and
then the area got swarmed by rats. Now whether or not frogs chirping is
a public nuance is up for debate. In rural America I HIGHLY doubt you'd
be in trouble (small number of ordnances). In suburban America you
might be in violation (crazy city folk control freaks move there and
make ordnances). In the city you probably are.

Now to your question, the neighbors can sue your friend in civil court
and if the noise is bad they could prossibly win. All they need to do
is convince the judge that your firend caused the noise (which they
did, they built a man made pond). They would however have to prove
damages if they wanted money which would be pretty hard, but they could
just ask the judge to make them remove the pond. Or the judge could
have a pond or like nature and tell the people to buzz off.



Sam