Tricks of the trade for some of Nome’s overwintering birds -- Part 2

With temperatures hovering around 30 below zero over the snowy, windswept landscape, early January seemed an uninviting time to be a bird in Nome. 
While the winter scene appeared devoid of food or comforts to most of us, the birds that overwinter here know where to look, and are experts at finding what they need to survive.
Let’s take a look at a few of the birds that winter in the Nome area and explore their behaviors, specialized adaptations and diets that enable them to eke out a living throughout a northern winter.

McKay’s and Snow Buntings
Buntings are cold weather specialists. Snow buntings nest further north than any other songbird and McKay’s buntings spend their entire lives along Bering Sea coastlines. They dress the part in dense white plumage that drapes over their legs and nostrils, minimizing heat loss.
As winter conditions become more extreme, buntings can quickly adjust their metabolism to put on body fat, and can tolerate a significant drop in body temperature, without risk of hypothermia. To escape severe conditions, they bury themselves alone in the snow for shelter and insulation. 
Buntings are one of the more noticeable birds around Nome in winter. They are seed-eaters that flock to bird feeders to gobble millet and sunflower hearts amidst cheerful chatter.
Out of town, mixed flocks of McKay’s and snow buntings roam the Seward Peninsula coastline where beachgrass grows. Flying low on white, black-tipped wings, flocks of buntings sweep along the beaches, leapfrogging each other as small groups pause to feed among the grasses. They find exposed seeds on the snow, or cling to grass stalks— sometimes bending them to the ground—while extracting the seeds.

Black-capped chickadee
These cheery northern residents have some very interesting cold-weather behavioral and physiological adaptations and are one of the most-studied of our winter bird companions.
Lively bundles of energy, black-capped chickadees are always on the go. By day, these little birds move through the willows in loose flocks, constantly exploring for seeds and frozen insects or larvae, all joining the feast when food is found.
In leafless thickets that look barren to our eyes, they manage to find and consume more than 35 percent of their body weight each day in calorie-rich foods that maintain their fat reserves and fuel their nights.
Roosting alone at night, crammed into tiny tree holes or crevices, chickadees fluff their feathers and enter a state of hibernation-like torpor to save energy. Their heart rate and respiration slow, and their body temperature drops to reduce heat loss. While shivering, they burn fat to generate heat. By morning their fat reserves may be depleted and must be quickly replenished at first light.
Chickadees needn’t rely on luck to quickly find breakfast, for they are well prepared. They cache food, and lots of it. A single bird may cache hundreds of seeds or frozen insects a day and remember where each is stored.
A chickadee’s hippocampus, which is the part of the brain used for spatial memory, is exceptionally large. In the fall when caching begins, the hippocampus grows even larger, especially so at northern latitudes where longer, harsher winters require more caching.
Research has found that black-capped chickadees of the north are 25 percent larger than those living in southern regions and able to store more body fat, which provides both insulation and fuel for staying warm.

Canada Jay
Canada jays are well suited to year-round life in cold climates. Their long, soft feathers fluff up for insulation, drape over their feet and legs for warmth and cover their nostrils to warm incoming air.
These jays are omnivores, eating all sorts of animal and plant foods, and anything they can scavenge from predator kills or human activities. Such a versatile diet is a big advantage in winter when food can be hard to find.
Like black-capped chickadees and ravens, Canada jays cache food in preparation for winter scarcity. They spend summer and fall gathering and storing thousands of bits of food and use their sticky saliva to glue it to hiding places under bark, beneath lichens, or in forked branches. They scatter their secret stashes throughout their territory and remember where to find them.

Common Raven
Bold, smart and opportunistic, ravens can make a living almost anywhere, and they are Nome’s most common winter bird.
The raven’s bulky body is an advantage in cold weather. Their robust body mass is large compared to their surface area, making them better able to retain heat than smaller birds.
In cold weather ravens depend on their high metabolic rate to continually generate heat. They are able to tolerate extreme cold without the specialized physiological adaptations that some smaller birds have evolved for heat retention.
Of course, this strategy requires regular intake of high-calorie foods. These resourceful birds are omnivorous and will eat almost anything. We provide well for them at the Nome landfill. Like our chickadees and jays, ravens cache surplus food for later consumption.
Ravens are well known scavengers, but they are hunters too, preying opportunistically on ptarmigan, other birds, and small mammals. And they are kleptoparasites, meaning they steal food from other animals. Twice, I have watched brazen thefts of freshly caught ptarmigan from gyrfalcons, once by a pair and once by a gang of ravens.
At night ravens depend on their dense plumage and sheltered communal roosting sites for protection from the elements. In the Nome area, various abandoned structures such as dredges have served as roosts.

Willow and Rock Ptarmigan
Clad in cozy, white camouflage, ptarmigan even grow feathers on their feet, which provides insulation and a snowshoe effect as they walk over the snow.
At night and during stormy weather, ptarmigan hollow out snug chambers in the snow, usually amidst shrubbery.  There they hunker, insulated by the snow and protected from bitter winds and cold.
In winter, willow ptarmigan feed on willow buds, while rock ptarmigan eat the buds and catkins of dwarf birch.
As the shrubs they depend on disappear under winter snows and their habitat shrinks, the birds may be forced to migrate beyond their breeding areas. In such cases, one might see nomadic flocks of hundreds of ptarmigan cruising low over the landscape, traveling as far as needed to find exposed shrubs that provide food and shelter.
Winter can be a challenging time for birds and other wildlife. It is when many populations experience their highest mortalities. Finding enough calories during short winter days to fuel long nights, while minimizing the calories burned obtaining them is a tough balancing act, in spite of all these marvelous adaptations.