On Wed, 6 Dec 1995, Herb Curl wrote:

> Commercial "bird bath heaters" are available in pet supply stores, sold as
> water heaters for dogs kept in kennels out of doors. They might be a
> little safer than any homemade variety.
>
> Herb Curl

I purchased an "official" bird bath heater two years ago for about $20.
I found that when it was really cold, leaving it on continuously resulted
in most of the water evaporating over night, and me writing larger checks
to the electric company. I've put mine on a timer now (another $10) that
turns it on about 1 hour before sunrise and turns it off about 1.5 hours
before sunset. A couple of other hints -- my bird bath is actually the
plastic bottom to a flower pot, so when it freezes at night it flexes
with the pressure. I also set it on the ground during the winter which
seems to help it thaw faster in the morning and probably keeps it liquid
better during cold days.

Kas Dumroese
Moscow, Idaho
dumroese at uidaho.edu