March 1, 2026: Warm Winter Homes

During our snowshoe trip through Page Pond last week we found a squirrel nest high in a Black Cherry tree, which caught my attention because I usually see Gray Squirrel nests in oak trees.  A gray squirrel nest can be identified by its location high in a sturdy tree, and almost always constructed with an outer layer of oak leaves.  They usually build their nest in an oak, probably for easy access to their preferred building material, but that isn't always the case as seen in that cherry tree and this pine tree:

A gray squirrel nest in a sturdy White Pine.

I've often wondered how a nest made of leaves placed high in the bare branches of an oak can survive through winter with the wind tearing at it for months - let alone how a squirrel can keep warm in there when it's 10 degrees below zero with a northwest wind howling.  And doesn't the resident get wet when it rains?  I found the answers to my questions in a book titled "Winter World" by Bernd Heinrich. [HarperCollins, 2003]  Heinrich explains that the gray squirrel builds its nest in the summer when the oak leaves are still green. 

In this nest - which is in an oak tree - some leaves still show some green color.

It chews off branches with the leaves still on them, brings them to the construction site, and then weaves them together to form the frame of the nest.  Thus the leaves are securely attached to the branch because without completing the fall leaf progression, the chemical process that released leaves from a tree doesn't take place.  They turn brown, but they stay secured to the branch, and that's how the nest survives the wind.

Here we can see branches woven together.

Next the squirrel will chew off green leaves which it layers and knits together inside the frame in a shingle-like manner to shed rain and snow melt, explaining how it keeps dry.  Finally, it will chew up soft woody material, bring it to the nest, and attach it to the green leaves all around to create a thick internal layer of insulation.  Heinrich doesn't say where the entrance hole is, but I expect it's near the bottom on the side away from the prevailing wind.  So inside that apparent random collection of oak leaves is a tight, dry, insulated home for the squirrel.  And that's important since squirrels mate in late winter with their offspring born in early spring.

With all that said, gray squirrels will also make a nest in a tree cavity for their winter home and raising their first of two litters.  But I know they were using the nest I saw in the White Pine because someone was up there making a racket - that's the only reason I found it - I went looking to see what was making all that noise.  I wouldn't otherwise look in a pine tree for a squirrel nest.

Red Squirrels have a similar nesting method and schedule, though there are notable differences.  Red squirrels nest lower in trees, and for some reason, tend to pick small, flexible trees.  This may be to discourage larger predators from climbing up to raid their nest.  Or maybe they just like to be swayed to sleep as the wind blows the tree around.

Here's another example of a red squirrel nest I've seen.

Did you notice the invasive bittersweet climbing all the trees?  😞  

As well as squirrels build protective nests, they alone are not enough to keep them warm in winter; they must eat constantly in order to burn enough calories to generate heat to keep them warm.  Small animals, unlike the large species such as moose, deer, and even beavers, don't have enough body mass to store much fat to burn during the winter.  But many small mammals, the red squirrel included, have a special attribute: it builds small stores of brown fat around its internal organs.  Unlike the more typical white fat, brown fat has a high rate of oxidation when burned which creates a lot of heat.  It's this heat that keeps the red squirrel warm on the especially cold days when it won't venture out to access the food stores it collected over the fall season.  To fuel its heat generating needs, a single red squirrel will need to collect thousands of pine cones in its winter pantries.  

A Red Squirrel's hoard of White Pine cones collected in the fall.

We don't see red squirrels as often as the gray, but this one has been visiting in the warmer weather this week (we saw 40 degrees!), happy to collect the easy pickings of all the bird seed its best friend the white-breasted Nuthatch shovels out of the birdfeeder onto the snow.

Gobbling up a high fat content sunflower seed.

The high energy content in sunflower seeds will regenerate its fat stores while reducing the depletion of its cone collection.  Red squirrels are fun to watch, but they can't top the antics of the gray squirrels.

Ah, yes, bright sun and 40 degrees - spring is here!  Meteorological spring that is.  March first is considered by meteorologists as when the weather patterns are more spring-like than winter-like.  There is still plenty of winter left in New Hampshire, and March is often the best time to enjoy winter activities such as skiing, snowshoeing, ice fishing, or just a walk on a pretty trail.  The WOW trail in Laconia is a prime candidate, just bring some traction devices for your boots.  Other options are the many snowmobile trails in the area, such as the trail between Lake Wicwas and Lake Winnisquam.  For those you'll need snowshoes.

The bog in the Chemung State Forest between Lake Wicwas and Lake Winnisquam.

With the deep snow cover and thick ice on the lakes, it will be an excellent season to enjoy your favorite winter activities!