Small birds, big preparations for winter
September 1, 2023 | View PDF
As we near the end of summer, many of us are planning for the winter months ahead: hunting, picking berries, canning vegetables, and freezing summer's food bounty. And the birds who will spend the winter with us are doing the same.
Many birds that live in Alaska year-round have clever strategies for ensuring they have enough food to get them through our long, cold winters. If you watch closely, you can see them gathering and caching food at this time of year. Some are scatter hoarders, hiding their foods in various places around the environment, and some cache food nearby.
Red-breasted nuthatches, the small songbirds who you see going up and down tree trunks seemingly upside down, stuff beetles and seeds under the bark of birch and spruce and often cover the cache with moss, lichen or even small rocks.
Black-capped chickadees are also busy this time of year, hiding seeds and insects behind tree bark, under dead leaves, between spruce needles or under moss.
The Canada jay also caches foods in multiple places in their territory, coating their finds with sticky saliva that helps to preserve the food for the long winter.
These three birds have learned that the antimicrobial properties in spruce resin help preserve their caches of insects and seeds.
The Boreal owl, a small owl primarily active at night, caches food too. Their strategy is to cache voles or shrews just before and after snowfall. They do not store their food long-term, like the chickadee, nuthatch or jay, but instead have a quick meal on hand after thawing their frozen prey using the heat from their feathered feet.
How do the birds that scatter their food around the environment remember where they hid everything, you might wonder?
Studies have found that chickadees in Alaska have larger hippocampus volumes with more neurons than their relatives in more southern latitudes. This gives them increased spatial memory to recall where they put that spider back in September.
Many studies of corvids (the family that includes ravens, jays, crows, and magpies) have found that these birds also have hippocampus adaptations that aid in spatial memory.
Birds who store their food must be aware of which individual birds are nearby when they are caching, as some are adept at stealing others' caches. To prevent possible loss of their cache, they may make sure they are out of the sight of potential thieves when they cache their food, reduce their caching efforts until the coast is clear, or space their food in various locations.
These birds' ability to plan for the winter by storing food and remembering where most of their caches are is impressive. Unlike us, they can't run to the grocery store weekly to restock their food supplies.
Even after the multitudes of summer birds have migrated out of Alaska, Bird Treatment and Learning Center remains open to care for injured and ill birds who keep us company throughout the winter.
Lisa Pajot is an ornithologist and Bird Treatment and Learning Center volunteer.