Why Do Squirrels Lie Flat?

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If you’ve ever startled a squirrel, you may notice a curious behavior.  Oftentimes, the squirrel will stop what it’s doing and lie flat on the ground.  

Even when it’s not scared, you may see squirrels lying flat on the ground or on a branch in a tree.

A red squirrel lies partially flat against the ground while carrying food in its mouth.
When a squirrel senses danger it will flatten all or part of it’s body on the ground. Red squirrel on the alert for danger. Photo: NPS/Robbie Hannawacker. Denali National Park.

There are several reasons for why squirrels will suddenly lie flat on the ground, a patio railing, or tree branch.

Squirrels Lie Flat to Hide and Survive

While it may seem counter-intuitive to suddenly stop in the presence of a danger, the act of lying flat is a protective mechanism for squirrels.  

Picture of a red squirrel sitting in a spruce tree, Denali National Park.
The underbelly of many tree squirrels is much lighter than its outer coast. Photo: NPS/ Robbie Hannawacker, Denali National Park

First, the act of lying flat hides the lighter colored belly of a squirrel. The fur color on the outer side of a squirrel evolved to help the squirrel blend in with its environment.

 If you’ve ever seen a squirrel against the bark of a tree, you will see how well the fur blends with tree bark (there are some exceptions where non-native squirrels have been introduced such as the melanistic eastern gray squirrel found in many communities around the United States).

Photo of a tree squirrel in Nez Perce National Historical Park.
Unlike the lighter colored underbelly, the fur on the outer body of a squirrel helps it it blend in with its environment. Photo: Nez Perce National Historical Park, NPS.

Second, the posture of lying flat on a surface also helps to protect the vital organs of a squirrel should it be attacked.  This posture also protects the genitalia of male squirrels from being bitten by other squirrels.

Squirrels Lie Flat to Cool Down

A hoary marmot relaxing during a sunny day on a rock ledge by the Eielson Visitor Center in Denali National Park, AK.
A hoary marmot relaxing during a sunny day on a rock ledge by the Eielson Visitor Center in Denali National Park, AK. Photo: NPS/Jen Wall

Beyond being a defensive strategy, lying flat has other benefits.  

Lying flat on a cool surface helps the squirrel cool down by dissipating body heat.  By spreading out the body on a patch of ground that is cooler than the surrounding air, the squirrels allows the superficial blood vessels to be in closer contact with the ground.

A ground squirrel resting on rocks.
A ground squirrel resting on rocks. Photo: NPS/Debbie Martinez

Lying flat exposes as much of the squirrel’s body surface to the cooler surface so that heat can be transferred from the squirrel to the ground. This strategy of reducing the squirrel’s heat load is called ‘heat dumping’.

Squirrels will find tree limbs, shaded pavement, and other surfaces that are cooler compared to the surrounding air to press their underbellies against. The fur on the squirrel’s belly is thinner compared to the thicker fur on the outer belly.

Squirrels Lie Flat to Rest

Lying flat in a tree when resting helps prevent the squirrel from falling out of the tree.

The prone posture also provides the sleeping squirrel with some protection from predators by camouflaging itself against the bark of the tree.

A yellow-bellied marmot, a type of ground squirrel, lies on a rock.  Photo: NPS, public domain.
A yellow-bellied marmot, a type of ground squirrel, lies on a rock. Photo: NPS, public domain.

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