Chickadees are small songbirds in the family Paridae that are known for their ability to withstand frigid winter temperatures. Of the North American chickadee species, the Black-capped Chickadee (Poecile atricapillus) has the largest range and is found across much of Canada and the northern United States. Black-capped Chickadees have adaptations that allow them to survive temperatures well below freezing. In this article, we will explore how chickadees are able to tolerate extreme cold.
Winter adaptations
Chickadees have several key adaptations that help them deal with cold winters:
- Fluffy feathers – Chickadees grow extremely fluffy feathers in the fall that provide excellent insulation. The added feathers increase their overall body size by up to 10%.
- Thicker coat – As temperatures drop, chickadees grow a thicker winter coat. This coat contains more barbules on each feather which allows more air to be trapped. More trapped air = better insulation.
- Shivering – Chickadees shiver constantly in cold weather to generate body heat. They can raise their body temperature up to 7 degrees F through shivering alone.
- Feather tucking – Chickadees can fluff out their feathers and tuck their bill into their scapulars to retain body heat.
- Huddling – Chickadees will huddle together in tree cavities at night and during harsh weather to share body heat.
- Increase metabolism – In winter, chickadees increase their metabolic rate up to 20-30% to produce more internal body heat.
These adaptations allow chickadees to maintain a constant body temperature even when outside temperatures drop well below zero.
Extreme temperature tolerance
So just how cold can chickadees tolerate? Research indicates that Black-capped Chickadees can withstand temperatures down to -20°F (-29°C) on a regular basis. During extreme Arctic blasts, they have been recorded enduring temperatures below -40°F (-40°C)!
In one study by the Cornell Lab of Ornithology, Black-capped Chickadees were exposed to -9°F (-23°C) for an extended period. Their shivering and feather adjustments allowed them to maintain a normal body temperature even at this frigid temperature.
How do chickadees keep warm in the cold?
Chickadees are able to maintain warm body temperatures during cold winters because of several key behavioral and physiological adaptations:
Grow winter feathers
– In autumn, chickadees molt their worn summer plumage and grow fresh winter feathers. These winter feathers are longer, fluffier, and more densely packed than summer feathers. This provides thicker insulation to trap body heat.
Increase fat reserves
– Chickadees purposefully increase their fat reserves in autumn. This subcutaneous fat acts like an insulating layer to conserve heat. Chickadees may increase body fat by up to 30%.
Fluff feathers
– Chickadees can fluff out their winter plumage to create air pockets. Trapped air is an excellent insulator. Tucking their beak into shoulder feathers conserves heat.
Huddle for warmth
– At night, chickadees will huddle together in cavities. By clustering their bodies, they reduce surface area and share body heat. This helps them conserve energy.
Crank up metabolism
– Chickadees increase their metabolic rate significantly in winter, sometimes up to 30% above summer levels. This ramps up internal heat generation. Shivering also generates heat.
Seek shelter
– Chickadees will hide out in sheltered microclimates like dense conifers during periods of extreme cold. This provides insulation from wind, snow, and low temperatures.
Adapt energy usage
– In winter, chickadees balance keeping warm with energy conservation. They reduce activity levels and eat frequent small meals. This provides fuel for heat generation without depleting reserves.
How do they find food in winter?
Chickadees rely on several strategies to find food during harsh northern winters:
Use memory
– Chickadees have excellent spatial memory and recall thousands of cache locations. This allows them to relocate stored food.
Seek natural food sources
– Insects eggs, berries, tree seeds provide nutrition. Chickadees forage actively on bark and vegetation for winter food.
Visit feeders
– Feeders provide a reliable food source when natural supplies are limited. Chickadees readily visit feeders stocked with black oil sunflower.
Travel in mixed flocks
– By joining mixed flocks, chickadees gain safety in numbers and share information on food sources.
Adapt diet
– Chickadees expand their diet in winter, eating more tree seeds, berries, and suet. This compensates for fewer insects.
Make caches
– Chickadees hide food in thousands of cache sites in autumn. This provides reserves when winter foraging is tough.
Eat frequently
– Chickadees cannot store much energy so they eat small frequent meals in winter. This provides constant fuel for heat generation.
How do chickadees survive winter nights?
Chickadees have several adaptations that help them survive frigid winter nights:
Seek sheltered roosts
– Chickadees roost in cavities or dense conifers that provide insulation and block wind.
Fluff feathers
– Fluffing out feathers creates insulating air pockets critical for retaining body heat overnight.
Huddle together
– To share warmth, chickadees huddle tightly in cavities at night lowering their surface area.
Reduce activity
– Chickadees are mostly inactive at night to conserve energy and body heat. They may enter short-term torpor.
Burn fat reserves
– Chickadees can safely dip into fat reserves at night as fuel to maintain a warm body temperature.
Adjust metabolism
– At night, chickadees lower their metabolic rate to conserve energy but not so much that they lose heat.
Take sun baths
– Sun bathing in the mornings helps chickadees warm up through solar radiation before another cold night.
How do chickadees thrive in such cold climates?
Though small, chickadees thrive in bitterly cold northern climates because they have many specialized adaptations:
Insulating feathers
– Thick winter plumage with dense, fluffy feathers retain body heat by trapping air.
Fat reserves
– Chickadees bulk up on fat each autumn which acts like insulation and provides energy.
Adapt energy usage
– Chickadees balance keeping warm with not exhausting reserves. They reduce activity in extreme cold.
Microclimate shelter
– Cavities, dense conifers, etc provide shelter from harsh elements. Chickadees use habitat to their advantage.
Social thermoregulation
– By huddling together, chickadees combine body heat and reduce heat loss.
Shivering and metabolism
– Chickadees can ramp up heat generation by shivering and increasing metabolism when needed.
Food caches
– Storing thousands of caches provides backup food when foraging is difficult.
Adaptability
– Chickadees can shift their diet and foraging strategies as conditions dictate.
These adaptations allow chickadees to regulate body temperature and energy balance even in extreme subzero temperatures.
What are some of the coldest temperatures chickadees experience in the wild?
Here are some examples of frigid temperatures chickadees endure in northern climates:
- Alaska – Temperatures below -40°F not uncommon in winter.
- Northern Canada – Routinely below -20°F. Can plunge below -30°F during Arctic blasts.
- Upper Midwest (U.S.) – Extended cold snaps bring temps from 0°F to -20°F.
- New England – Arctic weather can push temps down to -10°F to -15°F.
- Northern Rockies – Bitter cold is normal in winter with lows of -20°F.
These extreme subzero temperatures require chickadees to utilize all their specialized adaptations to maintain normal body temperature and survive. Their high tolerance for cold is remarkable.
How do chickadees keep their feet from freezing in winter?
Chickadees have several adaptations to prevent their feet from freezing in winter:
Countercurrent heat exchange
– Warm arterial blood flowing into the feet transfers heat to colder venous blood returning from the feet. This minimizes heat loss.
Reduced circulation
– Constricting blood vessels in the feet lessens exposure to frigid temperatures. Less blood flow means less potential for heat loss.
Insulative scales
– Leg scales cover the feet and help hold in heat much like feathers. Scales grow more dense in winter.
Hunkering down
– Chickadees fluff out leg feathers and settle down into snow burrows which insulates their feet.
Perching adaptations
– Strong feet and legs allow chickadees to shift positions and keep their feet against their warm body.
Tucking feet
– Chickadees can tuck their unfeathered feet up into downy flank feathers to conserve heat.
What is the coldest temperature ever recorded for chickadees?
According to records, some of the lowest temperatures ever documented for wild chickadees include:
- -46°F in Alaska’s interior in January 1971
- -43°F in International Falls, Minnesota in January 1910
- -40°F in Tower, Minnesota in February 1996
- -38°F in Fort Yukon, Alaska in December 1983
- -35°F in Saskatoon, Saskatchewan in January 1893
These extremely low temperatures were survived by Black-capped Chickadees and other northern chickadee species like Boreal and Gray-headed. However, even chickadees have their limits in these polar conditions. They relied on excellent winter adaptations to endure these frigid situations.
How does winter weather affect chickadee behavior?
Frigid winter weather causes several important changes in chickadee behavior:
Increased feeding
– Chickadees increase feeding rates and food intake to generate energy for staying warm. They eat frequent, small meals.
Feather fluffing
– Chickadees frequently fluff out their plumage in cold to trap insulating air pockets near their bodies.
Added vocalizations
– More frequent chickadee dee calls are believed to maintain contact in poor visibility and stormy weather.
Cavity roosting
– Chickadees start roosting in more protected tree cavities rather than exposed branches.
Shelter seeking
– During extreme cold snaps, chickadees spend more time hiding in sheltered microclimates.
Mobbing decreased
– Chickadees reduce their mobbing of predators in very cold weather to conserve energy.
Social cohesion
– Flocks stay tightly cohesive for added protection and warmth. Dominance hierarchies relax.
How do chickadees conserve energy in winter?
Chickadees rely on some key strategies to conserve energy during harsh northern winters:
Nightly hypothermia
– They allow their body temperature to drop up to 10-12°F at night, saving energy.
Short-term torpor
– During extreme conditions, chickadees can enter a short-term torpor to lower metabolism.
Reduced activity
– Chickadees cut back on unnecessary activity and movements to reduce energy expenditure.
Eat high-fat foods
– Shifting to fatty foods like sunflower seeds provides more calories per bite.
Cavity roosting
– Cavities provide insulation and lower heat loss compared to exposed branches.
Resting posture
– Adopting a well-insulated resting posture reduces heat loss.
Feather pillow
– Using tarsi feathers as a pillow retains body heat that would be lost through the feet.
Social thermoregulation
– Huddling together with flock mates reduces heat loss through shared body warmth.
Food caching
– Storing food saves energy flying around foraging when conditions are poor.
Conclusion
Chickadees are remarkably hardy songbirds that can withstand bitter northern winters far below freezing. Key adaptations like fluffy insulating feathers, cavities roosting, and hypothermia make their exceptional cold tolerance possible. At night, chickadees allow their temperature to drop to conserve energy while special countercurrent heat exchange mechanisms prevent freezing in their feet and legs. Though small, chickadees readily survive the harshest wintry conditions. Their adaptations provide valuable lessons on surviving extreme environments. With climate change increasing winter weather variability, understanding chickadees’ cold hardiness takes on added importance for wildlife conservation.