No caps, no mittens, just feed me

Birds have adapted over millions of years to deal with the killer weather we've had this winter.

Feeder birds don't need warm hats and mittens. They need food. Chickadees and other small birds need to eat and eat and eat.

Small animals need more energy to stay warm because they lose more heat than do large animals. Being small in cold weather is no advantage.

It is a matter of ratio, the amount of surface opposed to volume.

The Cornell Lab of Ornithology explains it this way. Consider a chickadee as a one-inch cube. Surface area is six square inches. Volume is one cubic inch.

Now, a turkey, which we will call a two-inch cube. This has a surface area of 24 square inches, a volume of eight cubic inches.

The chickadee has a surface to volume ratio of 6:1. The turkey's ratio is 24:8 or 3:1.

Shelter at night, which they find on their own in cavities or thick evergreens, is critical. Chickadees and other small species also can reduce their body temperature as much as 22 degrees Fahrenheit during cold nights.

Called regulated hypothermia, it's a lesser form of the inactivity level known as torpor.

The chickadees visiting our feeders tend to take a seed and fly to a nearby perch to eat. Flight takes energy. Bird engines run at high rpm.

Fuel to keep them warm is foremost.

Small seeds are easier for birds to process, as are seeds without shells. Black oil sunflower is sold in this form.

Meal worms, fresh or frozen, are an excellent source of protein and fat.

Suet pellets, about the size of a grain of rice, are available. There are pellets mixing suet and ground meal worms.

Water is important in cold weather. Liquid water is difficult to find in sub-zero temps, even though the sun now has regained some of its warming power.

At our feeders in late January the temp was minus-28.9. The first American Goldfinch to visit us in the morning went directly to the heated bird bath to drink. (We covered most of the water surface with a wide flat board to prevent actual bathing.)

CHICKADEE MECHANICS

They have a resting heart rate of over 500 beats per minute. That, by the way, is 3.26 billion beats in a chickadee lifetime of 12 years. Your heart, if you live to 70, will beat 2.5 billion times.

Generally, the smaller your size, the faster your heart beats.

Chickadees and other small species can reduce their body temperature as much as 22 degrees Fahrenheit during cold nights, research has found. Called regulated hypothermia, it is a lesser form of the inactivity level known as torpor.

Chickadees weigh about four-tenths of an ounce. A study at Tomsk State University in Russia found that the birds begin to lose weight as winter nights shorten. They need less fat for night heating.

The researchers said this change is triggered by the gain in daylight.