With night temperatures regularly dipping below the freezing point now, the extra food provided by backyard feeders may help many birds get through winter.
While there’s debate over the benefits — and drawbacks — of bird feeding in general, much of the current research shows that putting out food for birds in winter gives them a leg up in surviving frigid weather. A University of Wisconsin study showed that chickadees with access to birdseed during severe cold had a much higher over-winter survival rate (69%) as compared to those without access to feeders (37% survival).
Birds, of course, have developed their own strategies for withstanding intense cold. Many birds — bluebirds, chickadees, titmice, nuthatches, screech owls, downy and hairy woodpeckers and others — that nest in tree cavities and bird boxes during spring may use those shelters in winter to protect from night chill. On cold nights, many Georgia birds seek protection in thick evergreen trees, shrubs and hedges from harsh wind, rain and snow.
Birds also have physiological adaptations — such as natural insulation — for staying warm. Some tiny birds, such as Carolina chickadees, also go into a state of “regulated hypothermia” on frigid nights. Their body temperature drops 10 to 15 degrees, which saves them about 20%-25% of the energy normally required to maintain average body heat.
Even so, after a freezing night, it’s important for birds to be able to quickly refuel in the morning when their high metabolic rates and body heat go back up. Ample food in winter, then, is vital for the birds. It could mean the difference between starvation and survival.
Here are some tips for winter bird feeding:
• If you hang just one feeder, choose a tube feeder with metal ports around the seed dispensers to deter squirrels. Hang it at least 5 feet off the ground.
• Keep feeders clean to prevent disease.
• Black oil sunflower seeds attract the widest variety of birds; suet attracts woodpeckers.
• Provide clean water — essential in winter, as it is at any other time of year.
IN THE SKY: From David Dundee, Tellus Science Museum astronomer: The moon will be last quarter on Tuesday. Venus and Mars are low in the east just before sunrise. Jupiter and Saturn are low in the west just after dark.
Charles Seabrook can be reached at charles.seabrook@yahoo.com.
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