Birds in Winter & the Fascinating Brain of a Chickadee

Nature Highlights

About the Author: Claire O'Neill ➔

Claire is a co-founder of Earthwise Aware (EwA), an environmental nonprofit that brings biodiversity knowledge and science, ecological ethics, and environmental leadership to the heart of communities. She is the director of EwA's Biodiversity & Climate Participatory Science program– an initiative that connects the public with its immediate natural systems and empowers communities. EwA focuses on place-based urban wildlife and natural history, and the conservation of species interactions. Its program runs regular continuous biodiversity and phenology studies in 8 cities. The program fosters a deeper understanding of ecological systems and provides tools to the public to make evidence-based environmental decisions. Locally, Claire is a co-organizer of the iNaturalist City Nature Challenge for the Greater Boston Area. She also serves as a board member of the Friends of the Fells, and is an advisor for the Green & Open Somerville group. [More...]

Claire strongly believes that individually and altogether we can be ethically & ecologically engaged–whoever we are, whatever we do, and wherever we are. Ethical Nature conservation is not circumstantial, it is a mindset that you acquire which then turns into a way of life. Once on that path, a great many rewards for us becomes obvious. And the satisfaction out of practicing good ethics is almost addictive. There is no looking back...

Her favorite motto: “Nature Conservation as A Way of Life”

EwA Nature Highlights
Season: Winter | Location: New-England’s meadows, parks, and gardens

Enjoy winter birding. Look for adaptions that are likely to help birds in winter.

EwA runs biodiversity walks monthly when we invite our guests to observe with us the passage of the seasons on the local flora and fauna. Each exploration is a chance to highlight nature chronicles that we may enjoy together right at the time of the walk. Check EwA’s events calendar 📅 and come discover with us the hidden stories of our urban green spaces.


Winter is a special time. The trees open up to the sky. As there is less leaf-distraction, it provides a great opportunity to zoom out and observe birds while thinking about the different adaptations that they have evolved to cope with winter.

Here are a few: 

Migration. Some birds leave for a warmer climate.

Feet. Fewer arteries, mostly tough tendons, meaning reducing heat loss. Some birds grow extra pads in winter.

Countercurrent heat exchange system. Heat loss is reduced by 90% in a bird’s extremities by reducing the diameter of the arteries in their legs and by an exchange of heat between arteries and veins (that are adjacent in birds).

Feathers. Birds have 6 types of feathers, including the insulating semiplumes and down feathers.

Fluff and tuck. Ever wondered why there are so many headless birds standing on one foot in winter? They tuck to reduce exposure to cold, and decrease heat loss. Some birds fluff to trap as much air as possible between their feathers – air that will warm and provide an additional insulation layer. 

Shivering. Quick muscle spasms convert energy into heat (goldfinches are notorious shiverers).

Torpor. Some birds, such as doves, experience a temporary and radical decrease in metabolism. Some birds can easily look dead or nearly dead when in torpor (like hummingbirds)!

Fat reserves. Many birds gorge on food in the fall to accumulate fat for the winter.

Cache for later. Birds like chickadees (Poecile atricapillus) store large supplies of seeds in many different places in the fall to prepare for soon-to-be hard times


Speaking of chickadees, do you know that they are the Massachusetts state bird? I so enjoy their distinctive chick-a-dee-dee-dee and whittled fee-bee calls. I love seeing them hiding in the spruces in my driveway lurking at the seed heads of the native wildflowers in my garden. In wintertime, you are likely to see chickadee groups mixed with nuthatches, creepers, kinglets, titmice, and other birds. ‘Strength is indeed in numbers’ for finding food as well as for protecting the group against predation!

In late summer and early fall, an interesting biological phenomenon happens to our chickadee friends: As they gather and cache food for the hard times to come, their brain expands by about 30% in volume. The hippocampus (the part of the brain that supports spatial memory) grows new brain cells that help them remember where they stash their winter food supply. It is now assumed that as the bird’s memory space capacity limit is reached, then old cells are discarded to leave room for new information. Then in spring, when there’s less need to remember where stuff is, the chickadee’s hippocampus shrinks back to its normal size. Remarkable adaptation, isn’t it?

So… ‘Bird brain’? I don’t think so! If anything else, chickadees teach us that there is a lot that we don’t understand and that there is so much more for us to observe and marvel at right from our backyards, parks, and city streets.


Enjoy your time outside exploring Nature’s wonders right in our yards, parks, and urban forests. Share your findings with us (you can comment below)!

If you want to learn more about chickadees (e.g., controlled hypothermia, social structure, etc.), or about the natural history of our urban natural places, from birds, insects, animals, to plants, how they work together, and how you can help protect urban nature, I invite you to join our Biodiversity Walks 📅.


EwA Useful Links

🦅 EwA Field Guide – Birds in Winter, Deadwood & Springtails (pdf)

📸 EwA New England December Biodiversity Sightings through Time

📖 Birds: A Complete Guide to their Biology and Behavior (2016) by Jonathan Elphick

📰 Seasonal Hippocampal Plasticity in Food-storing Birds by Sherry DF, Hoshooley JS in Philos Trans R Soc Lond B Biol Sci. 2010;365(1542):933-943. doi:10.1098/rstb.2009.0220


by Claire O’Neill I Nov, 28th 2021 

The photos in this article are visual records that the EwA team has collected in the Greater Boston Area. Click on any picture, and you’ll land on the record and its owner. Photos are licensed under Attribution-NonCommercial (CC BY-NC). 

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