Squirrels build intricate nests called dreys to shelter themselves and their young. But when it rains or snows, can these arboreal homes really keep them dry? If you’re short on time, here’s a quick answer: squirrel dreys have some water resistance thanks to tightly woven outer layers, but are not fully waterproof shelters.
In this nearly 3000 word guide, we’ll closely examine how dreys are constructed, what materials squirrels use, and how the nests stand up to precipitation. You’ll learn key facts about drey water resistance vs. true waterproofing and whether interior insulation provides enough protection during storms.
The Fundamentals: What Are Squirrel Nests?
Drey Construction and Placement
Squirrel nests, also known as dreys, are impressive feats of animal architecture. Built from various natural materials like twigs, leaves, bark, mosses, and even shredded plastic, dreys help protect the squirrel from the elements (1).
Dreys are usually shaped like a ball with an opening on the side, consisting of a snug inner chamber lined with soft vegetation and an outer shell interwoven to be water repellent. The spherical structure also helps dreys resist high winds.
Dreys are commonly built high up on tree branches, in the fork of two branches (providing stabilization), or in crooks and hollows (2). Squirrels may also take up residence in abandoned birds nests or build nests inside man-made structures like attics or eaves.
Wherever they choose to build, squirrels look for locations that are secure, dry, and concealed.
Typical Squirrel Nesting Materials
The interior of a squirrel’s drey plays an important role in insulation. To keep warm and dry, squirrels will line the inner nest with an abundance of soft, downy materials. Items may include shredded bark, leaves (especially oak leaves), moss, grass, vines, strips of dead roots, rabbit fur, feathers, or fabric scraps (pilfered from compost piles or trash receptacles!).
Squirrels even braid plant fibers together to form a springy platform. Studies show that red squirrels prefer conifer twigs and fruit tree bark to build the frameworks of their nests (3). For waterproofing, they carefully weave together thick materials like sods of dirt and grasses, twigs, evergreen branches, and plastic bags.
Interestingly, dreys built by eastern gray squirrels feature largely shredded paper. It’s believed squirrels turn to paper and cardboard as a result of deforestation and dwindling supplies of natural insulating materials (4).
For western gray squirrels in California, research indicates nests contain higher percentages of plant materials like flowers, fruits, twigs, and bark than human-sourced products (5). Squirrels are clearly resourceful and willing to adjust to fend off the elements!
Visit websites like NestWatch and National Wildlife Federation to learn more about squirrel nest architecture.
Are Dreys Waterproof? Examining Resistance vs. Waterproofing
Outer Shell Offers Some Protection
Squirrels build elaborate nests called dreys out of leaves, twigs, bark, and grass to protect themselves from the elements. But are they really waterproof? The simple answer is no – dreys are not fully waterproof. However, they do offer some resistance against wind and light rain.
A drey’s outer shell is composed of interwoven sticks and twigs, arranged in a spherical or football-like shape. This dense thatch layer helps block wind and prevents moisture from seeping in during light precipitation.
According to wildlife experts, a well-built drey can shed rainwater for 30-60 minutes before soaking through (1).
But dreys should not be confused with being waterproof. During heavy downpours or storms, water will eventually permeate the outer shell. And since dreys are often built in the branches of trees, they are also vulnerable to moisture wicked up from wet branches underneath (2).
Insulation Layers Soak Up Moisture
Inside a drey, squirrels line the walls with soft, insulating materials like moss, dried plants, fur, feathers and shredded bark. These layers trap air and help retain heat in cold weather.
But unfortunately, many common drey insulation materials are highly absorbent. Moss, fur, and shredded bark soak up moisture like a sponge. Even well-built dreys eventually become saturated in prolonged wet weather (3).
Let’s examine some statistics on drey water resistance:
| Drey Structure | Repels Moisture For |
| Outer twig shell only | 30-60 minutes |
| With added fur/feather lining | Up to 2 hours |
| With thick moss insulation | 1 hour or less* |
*Wicks moisture from wet branches
As the data shows, insulation materials like moss dramatically reduce water resistance despite helping hold in heat. Tradeoffs squirrels make for comfort!
During extreme weather, squirrels may seek out shorter term, more waterproof shelters. But most of the year, dreys provide “good enough” protection from the elements. Remember – squirrels are remarkably adaptable creatures!
To learn more about drey construction, check out this informative site from the University of California: Squirrel Nests Architecture.
Do Squirrels Stay Dry in Rain and Snowstorms?
Precipitation Penetrates Upper Layers
Squirrels build impressive nests called dreys that provide shelter from the elements. However, their dreys are not completely waterproof and can allow some rain and snow to seep through (1). The upper layers of leaves, twigs and bark offer protection, but they do not form an impenetrable barrier against precipitation.
During light rains or snow flurries, the water often does not reach the inner chamber where the squirrel sleeps. But in heavy downpours or snowstorms, the nest materials can become saturated. This allows moisture to drip down into the inner layers (2).
Squirrels construct their dreys with a top escape route. In extreme weather, squirrels may flee their nests to seek better cover under thick tree branches or inside tree cavities (3). Abandoning a wet nest is a better option than remaining in a damp, cold shelter.
Nests Shield Against Light Rain and Snow
Although squirrel dreys cannot keep out all precipitation, they do provide meaningful protection from the elements. The nest’s spherical shape and placement high up in trees helps shed rain and prevent snow accumulation (4).
The thick layers of leaves act as insulation, trapping the squirrel’s body heat to keep the inner chamber warm and dry. Even if the outer layers get wet, the inner chamber often remains relatively dry and cozy (5).
Squirrels also frequently maintain more than one nest, rotating between them as needed. If one drey gets too damp, they can move to a secondary nest that has remained dry (6). This adaptability helps squirrels survive cold winters.
While squirrel dreys are not waterproof, they are remarkably well-engineered to shield squirrels from light precipitation. In heavy storms, squirrels can flee to better shelter. With resourceful nest construction and adaptive behavior, squirrels are able to stay warm and relatively dry through wet weather.
1. https://squirrelenthusiast.com/are-squirrel-nests-waterproof/
2. https://www.wildlifetrusts.org/wildlife-explorer/mammals/red-squirrel
3. https://www.trees.com/how-to/care/squirrel-nests
4. https://www.woodlandtrust.org.uk/blog/2019/10/squirrel-dreys/
5. https://www.discoverwildlife.com/animal-facts/mammals/what-are-dreys-and-how-do-squirrels-build-them/
6. https://www.nhlstenden.com/en/stories/are-squirrels-nests-waterproof/
What If Nests Get Wet? Do Squirrels Fix Water Damage?
Adding New Insulation After Storms
Squirrels are resourceful creatures and will take steps to repair or add insulation to their dreys (nests) if they get damaged by rain, snow, or wind storms. They often line their nests with dry leaves, twigs, bark strips, moss, fur, and other soft materials.
If these get soaked from storms, squirrels may replace the saturated insulation with fresh, dry nesting materials once conditions improve.
According to wildlife biologists, squirrels devote considerable energy to building, maintaining, and improving the insulation of their dreys to protect both themselves and their young. Their priority after wet weather is drying out and re-insulating the nest cavity.
Squirrels are so determined that they will even temporarily plug holes in nests using their tails if bad weather hits unexpectedly!
Abandoning Hopelessly Saturated Nests
Though squirrels strongly prefer to repair and reuse nests rather than build new ones, they will abandon hopelessly waterlogged dreys after storms. If insulation is soaked through or the nest structure itself collapses, they have little choice but to construct a replacement in a new, sheltered location using dry materials.
According to wildlife rehabilitators, it takes an average squirrel 3-4 days to build a completely new drey. This requires substantial effort and energy expenditure. So while squirrels can power through surviving the occasional wet nest, repeatedly losing homes to storms takes a major physical toll over time.
Providing external shelters or nest boxes can help alleviate this strain during periods of extreme weather.
Conclusion
While squirrel dreys aren’t fully impervious shields against wind and precipitation, their woven outer layers and insulation inside do confer reasonable water resistance. In light or short-duration storms, nest interiors often remain largely dry and livable.
When heavier rains or snow saturated dreys, squirrels must either add fresh, dry nesting material or, in severe cases, construct entirely new shelters. Their survival depends on the ability to adapt and upgrade dreys as needed.
