I'm looking out at about 5" of fresh snow this morning in Boulder, and I know my bird bath at home is going to be busy today. There's no doubt that a clean water source can bring in birds as well as (if not better than) feeders, and I find that when there's snow cover or very cold temperatures this is especially true, as other open water gets covered or frozen over.
Last summer I upgraded from a drip system to a circulating fountain-style bird bath, obtaining a Bird Spa after a hearty endorsement from Julie Zickefoose. There was just one hitch- the directions said not to use it below 25° F (using a heater at that), a temperature we regularly go below in Colorado. Well, I guess I took that suggestion as a limit that could be exceeded if the proper precautions were taken. (Note- attempt cold-weather bird watering at your own risk- I make no claim to the sensibility of the following modifications...) I went to my favorite store, McGuckin Hardware, and found an insulating foam wrap with silvery backing that they sold by the yard. I gave the Bird Spa reservoir a wrap with an old closed-cell foam sleeping pad and then a good double-wrap with the silvery stuff and taped it all up. In the reservoir I placed a bird bath heater like this. I used to pop the circuit breaker sometimes on my old system, especially when I had Christmas Lights on the same circuit, so now I run a really heavy-guage power cord out from my garage's dedicated 20-amp cicuit to avoid the bad surprise of losing power to the spa on a cold night (thanks, pop-in-law, for helping me put that in last year- a most excellent addition to the garage, AKA man-land.) We had a couple of really cold snaps in December, including a low of -12° F the night after the Boulder CBC, and the spa kept bubbling along. The only problem I've had this winter was one night when Chinook winds really cranked (with gusts of 80+ mph- not much sleep that night...) blowing all of the water out of the spa (not to mention a few shingles off my roof.) Luckily, the pump must have had a little water left around it in the bottom of the reservoir because it didn't burn out- when I re-filled it and plugged it back in it went right back to circulating the water. Here's a typical scene looking out my kitchen window on a cold, snowy morning- note the insulating wrap. I also shovel snow around the base when we have the white stuff to add insulation, because the bottom is up off the ground for the drain and for the cables to go up and into the reservoir throught the overflow tube.Eurasian Collared-Doves queue up in the tree above the bath to wait their turn, and American Robins enjoy a drink and often a splash.Meeker birds wait for the big boys & girls to finish up. A Pink-sided Junco may be expected but is always welcome. Occasionally something more exciting comes to take a turn, like this Yellow-rumped Warbler. I've got to say that mid-winter warblers really make my day!