Barking at Rabbits

Greetings,

We recently moved into a new neighborhood where there are now a lot of
rabbits. The rabbits either sit inside the fence, and my dogs bark at
them from indoors, or they sit outside the fence, and my dogs bark at
them from indoors OR outdoors. Every once in a while, my dogs are
outdoors, and a rabbit is inside the fence... they chase it all over
the yard, until the rabbit figures out how to get out of the fence.

The biggest problem here, is the barking. When they are not barking,
they are obsessing about rabbits that _might_ be outside. It doesn't
matter if they are out there or not... they obsess endlessly about the
rabbits.

Any suggestions for what I should do about this? Their barking is
unbearable when they are inside, and I don't want to annoy my neighbors
when the dogs are outside.

My two dogs are:
Stella -- Female 7 year old rescued Greyhound
Mona -- Female 3 year old spaniel mutt

I fear that the root of this is probably the fact that the greyhound
was trained to chase rabbits when she was a track dog.

Rocky...

How long has this been going on? I've hares running down the
middle of my street and eevil squirrels burying peanuts in my
front lawn under the watchful eyes of my dogs. While they bark
at many other things, they've gotten used to the rodents.

The only thing we have tried so far is yelling "No" (which they
understand) when they are barking. We are considering squirt guns
(they both hate water) or ultrasonic anti-bark devices... but that only
fixes the symptom.

What to do?
B