It's 57 degrees on my back porch, but I am wary about the winter to
come. This little compendium of the winter strategies of the chickadee
makes you wonder at how they do it.
Bill Whan

MD: From January 2018 FOSC Newsletter:How Do Our Tiny Chickadees Survive
the Frigid Cold?
Five basic adaptations help our Carolina Chickadees (and their close
cousins, the Tufted Titmouse) get through the kind of brutal cold we
recently experienced.
Like many birds, chickadees and titmice fluff out their feathers in a
cold snap, which makes them look fat but adds many layers of insulating
air between their bodies and the cold. Studies have shown that bird
feathers provide much better insulation than mammal fur.
A second way they maintain daytime body temperatures is to shiver, which
burns calories but generates heat.
Another adaptation allows chickadees to drastically reduce their body
temperature at night by more than 50 degrees Fahrenheit, from 108 to
about 50. This process of "nocturnal hypothermia" saves considerable
energy because the birds don't burn precious fat to maintain their
daytime body temps over the long winter nights, which they spend alone
in tree cavities.
Chickadees can add 30 percent more brain cells in fall for remembering
hundreds of hidden seed locations.
A fourth adaptation to cold is their ability to store vast numbers of
seeds in hidden caches all over their huge flock territories in winter.
A single chickadee can cache tens of thousands of seeds a year, each
seed in its own hiding place, usually behind strips of bark. Some
chickadees have been observed caching 1,000 seeds in a single day.
This caching of seeds would be useless without the chickadee's
astonishing ability to remember their locations, which they do almost
without fail over winter territories up to ten square miles.
Their remarkable spatial memory is created by a whopping 30 percent
increase every fall in the capacity of the hippocampus, that portion of
their brains (as in mammals) devoted to spatial memory.
In 1994, it was discovered that chickadees add a tremendous number of
nerve cells to this part of their brains as winter approaches. Since
then, scientists have shown that seasonal brain enlargement in
chickadees is greater in more northern latitudes and at higher
elevations, even in the same species.
Lab studies show that chickadees remember thousands of seed locations by
relating them to angles or distances from landmarks.
(nationalgeographic.comdrawing)
Since severe cold (and predators) inevitably take their winter toll on
chickadees, their backup plan is to rear up to nine chicks every spring,
which improves the chances that a few will make it through the winter,
no matter how cold it gets.


-- M. Wilpers, Natural History [log in to unmask]

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