Winter can be a time of drought for north country birds. Available sources of water may be frozen, but our avian friends' needs for drinking and bathing remain. In harsh winters like the one we're experiencing this year, it's a kindness, indeed, a survival mechanism to provide a source of clean, reliable water. And if you wish to have bird buddies help keep your garden clean of noxious insect pests once spring arrives, it's wise to help them out now.
It's not that difficult. I keep the plastic birdbath attached to my deck rail, adjacent to the hanging finch feeder filled 12 months a year. Come mid-November and the first freezing nights, I string an extension cord some 12' from my screened porch to the birdbath, and plug in a small heating element which sits in the water. I've learned to anchor it with a stone, as in the past it's shifted in a high wind, or been dislodged by an eager jay. Such implements use little electricity, shut off when temperatures are above freezing or the water reservoir runs dry, do not harm the birds, and are available comercially in several modes. They keep the water just above freezing. (Mine is a Nelson Blue Devil, purchased 3 years ago at Agway, for approximately $40.)
The water must be kept clean, of course. The water quickly fouls without a twice-a-week attention. I use a soft-bristled brush saved for the birdbaths, and simply dump out the old water, swish the brush around a couple of times, then rinse and refill with a small pitcher of water I've brought along. Takes all of 3 minutes.
Birds have been know to eat snow, break off icicles, and even catch snowflakes to obtain needed water. But Nature doesn't always furnish icicles or snow, and anyway, who would deny themselves the sight of a small junco, wren or finch dipping its beak into the fresh, clean water you've provided these winged beauties?