What is special about a squirrel's nest?

The Hindu

07-05-2025

'Where does a squirrel live?' I ask.
'A tree? In a hole?' my colleague replies, her eyebrows furrowing into a question mark.
'A cavity? They just store nuts and make that cavity a home. I don't think they build nests. Is this a trick question?' asks another, a little confused.
Lately, I've been asking this question to many people—mostly in an attempt to reassure myself that I wasn't the only one unaware of the nesting habits of this little rodent. A cavity was what I thought too. It never occurred to me that squirrels would spend time crafting elaborate nests, much like birds do.
I was proven wrong a few months ago when a squirrel decided to make its home on my bathroom windowsill. A brown, round, messy circular-shaped structure made of cotton, twigs and dry grass had appeared out of nowhere. And in it, a squirrel.
Why do creatures make nests?
'The main reasons for making nests is for protection from predators (and weather phenomena like storms, heavy rain), breeding and thermoregulation,' says Sreejith Sivaraman, who is doing PhD in community ecology of rodents under Dr. P Balakrishnan, senior scientist, Kerala Forest Research Institute (KFRI).
'With the rapid increase of urbanisation, green cover has disappeared and squirrels try to seek shelter and make nests in buildings (and branches of trees due to lack of cavity bearing trees. This behaviour is not seen in the wild among squirrels). They might perceive that these regions, closer to humans, may pose less of a threat and that they could provide them safety from predators such as snakes and raptors (or birds),' he adds.
Squirrels and nesting
Squirrels belong to the rodent family and their nesting habits are species specific. The Indian palm squirrel, the three-striped squirrel that we normally see around us chooses hollow trees, cavities, etc to make their nests. As green spaces reduce, different species of the urban wildlife tend to compete among themselves for making their nests, because of which they might end up choosing buildings. Interestingly, the materials used for nesting also differ between a squirrel living in the forest and one in urban areas, says Sreejith.
In the wild, a squirrel could make use of materials such as dry leaves, moss, twigs, tree bark and natural fibres to make nests. When it comes to urban areas, they take what is available, including plastic.
Nesting habits
The female squirrel will start building its nest once the mating process is complete. In two days it would have built its nest. The gestation period for the squirrel is 40-45 days and the litter size varies from 2 to 4. The babies will open their eyes in 24-30 days. They are hairless and sport a pinkish colour when they are born. 'In two weeks time they will get their incisors. One unique thing about the incisors is that they are ever growing. In the case of rodents, their incisors never stop growing, which is why they need to keep gnawing at something, to keep it shaped and small. If not, these could grow longer, pierce into their jaws and even cause death,' he says. From the 12th day, their hair will start growing. The babies will feed on the mother's milk and the chewed food she provides for up to two months. After that, they will be ready for solid food. Once they become adults, they are ready to leave the nest.
The process of nest building is different in different species of squirrels. Giant squirrels are seen to make multiple nests in trees. They will choose the highest canopy and build multiple nests. They can finish each nest in a matter of hours. On a given day they would complete two nests. Once complete, they choose a nest which they feel is safe among the nests they have built. 'They build multiple nests so they can confuse the predators. Further, they can also move their babies between these nests once they perceive a threat or a predator attack' says Sreejith.
Struggles in the urbanscape
Life in the urban areas is a challenge for these species. 'What has to be noted is that they didn't arrive from the forests. They have been living in our urban landscape. But as the frequency of urbanisation increases and tree cover and microhabitats are lost, life gets challenging for them,' he says.
What can you do then, as a human living in an urban setting?
Co-existence and preservation of microhabitats
The definition of a healthy tree may vary from the perspective of a silviculturist or a commoner and an ecologist. A healthy tree is not one that flaunts a golden-brown tree bark with no cavities. 'But one with cavities and fissures. Because these are microhabitats, which give a home to a wide range of species. Take, for example, a dry tree or log. These are microhabitats in which many species could be living,' says Sreejith.
As the march of our civilisation amplifies and continues, animals are finding it harder to exist amongst us. So what can be done? 'The answer is co-existence,' says Sreejith. 'We have to let them be. If they invade our spaces it is because they are losing their habitats. So we can learn to coexist with them, without disturbing each other,' he says.
And so, the squirrel raised her family there—on my windowsill. She returned yet again, to raise the next. Whenever she senses my presence, she shifts and moves about. Earlier, she would get agitated and swiftly dash out into the world, and all I'd see was the flicker of her furry tail. Now, I see a mound of grassy ball slightly quiver and tremble—as she shifts in her home, perhaps a tad unsettled by my presence. Then she reassures herself and retires.
I named her May, this month—and together, we are learning about co-existence.