When the weather turns chilly, my thoughts turn to birds coping with cold — sometimes very cold — weather. Usually that motivates me to sound like your mother and write the annual for-Pete’s-sake-clean-your-dirty-birdfeeders column (with directions), followed by the annual how-birds-stay-alive-in freezing-weather-and-what-you-can-do-to-help column.
This year, getting right to the point, and assuming that you can watch one (or more!) of about 7,390 YouTube videos on cleaning your bird feeder:
Bird droppings! Mold! Infectious diseases! Bacteria! Fungal spores! Salmonella! Avian conjunctivitis! Respiratory problems! Death! Enough said!
Birds won’t starve if you’re not around to replenish the feeder. Like any human diner, if the restaurant is closed, they’ll move on to a different restaurant, your neighbor’s or the one nature offers. All birds do not survive very cold winters for a variety of reasons.
Bird feeders during winter are valuable to birds, especially filled with a combination of fatty foods such as black-oil sunflower seeds and suet. However, researchers have found that one of our most loyal customers, chickadees, eat about 25 percent of their winter food from feeders.
But does it really help? In 2008, researchers found that extra food for at least one species of garden birds during the winter makes a more successful breeding season in terms of laying eggs earlier and average one more surviving bird per clutch. Five years later, another study found that feeding fat balls to wild blue tits in winter resulted in less successful breeding the next spring, according to Science Reports.
Birds are warm-blooded, with temperatures around 106 degrees. They get cold. Smaller birds lose heat more rapidly than larger birds. There are different methods to stay alive in the cold. Food generates heat, and fluffed-up feathers help keep the heat inside and the cold away from their skin. Birds will sit in the sun. Some smaller birds can add fat, too.
Others will shiver to raise their metabolic rate (chickadees are experts); this works but it requires more calories, so there’s another chance for birdfeeders to come into play. Waterproofing their feathers with body oils keeps inside feathers and skin dry. Larger birds will add a layer of fat as insulation, or grow an extra set of downy feathers.
Some birds can lower their internal body temperatures and save energy, but it’s not as common a technique as one might think. If a bird drops its body temperature for the night (torpor), it has to raise its temperature in the morning, and that can take too long and requires more energy, according to the National Audubon Society.
While hummingbirds can drop their internal temperature close to outside temperatures, black-capped chickadees use a moderate version, according to the NAS. They reduce their temperatures as much as 22 degrees from daytime levels, a process called regulated hypothermia.
If you have a birdhouse, consider leaving it up (after you have cleaned it out) as a shelter against winter winds. Some species will huddle together to combine their body heat. Dense foliage is another opportunity for birds to get out of the wind.
Despite all odds, many Anna’s hummingbirds stay here during winter. Keep your hummingbird feeders full, and you’ll probably be rewarded. If it’s likely to freeze, bring it inside at night and put it back out in the morning. Some people have wrapped their feeder in Christmas lights, or hung a turned-on lightbulb close by to counter a light freeze or provide warmth for a hummer. The more sheltered your feeder the better.
Birds need water, but if they get their feathers wet in your bird bath, the feathers could freeze and the birds could die. Set out water in small containers that are deeper and less likely for the birds to jump in.
Attracting birds to feeders is as much for our entertainment as for their supposed well-being. It probably does no harm unless you slack up on: Bird droppings! Mold! Infectious diseases! Bacteria! Fungal spores! Salmonella! Avian conjunctivitis! Respiratory problems! Death! Enough said!
Columnist Sharon Wootton can be reached at 360-468-3964 or songandword@rockisland.com.
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