With their bushy tails and quick movements, squirrels delight many who spot them foraging or playing. But are squirrels truly as cute and harmless as they appear, or do they have a darker side? If you’re short on time, here’s the quick answer: squirrels do display some aggressive behaviors, but overall they tend to avoid conflict when possible.

In this nearly 3000 word article, we’ll take a comprehensive look at various squirrel behaviors to help you better understand these common backyard critters. We’ll explore whether aggression is common among squirrels, what situations tend to bring out squirrel aggression, defensive tactics squirrels use, and whether squirrels make good pets.

Squirrel Aggression: How Often Does it Occur?

Territorial Behavior

Squirrels are highly territorial animals that establish their own domains consisting of nesting sites and foraging areas. According to research from the American Society of Mammalogists, male squirrels defend territories of 0.5 to 5 acres depending on the abundance of resources, while female squirrels occupy nesting sites and smaller feeding areas of around 0.5 acres.

Encounters at territory boundaries often lead to aggressive chases and occasionally, physical combat.

A key factor influencing aggression is population density – the higher the density, the more instances of hostile squirrel interaction. One study in an urban area recorded chase encounters at a rate of once per hour during peak autumn activity.

In more sparse wild habitats, serious physical altercations may occur a few times per month. Overall, chase encounters happen fairly regularly in squirrel populations, but outright combat is less frequent.

Mating Competition Aggression

The breeding season brings a major spike in aggressive behavior among normally solitary squirrels. Male squirrels compete vigorously for opportunities to mate with females that briefly enter estrus. Dominant males chase subordinates out of their territories and engage in battles that researchers have described as “wrestling matches” where opponents grab each other with forepaws and teeth, dragging one another in circles.

These fights resolve social hierarchy for breeding priority. In one population, males fought up to 14 times per hour across a two month mating season. Females may also mount aggressive defense of their nests sites against infanticidal males.

All in all, the mating period accounts for a substantial portion of annual squirrel aggression.

Aggression Over Food Sources

While squirrels mostly forage alone, preferred food sources like large seed mast crops or balcony bird feeders bring high densities of squirrels into close contact. This drives up competition and territorial behavior. Aggressive scrambles break out routinely at rich food patches.

A famous study of spruce mast yields found yearly spikes in squirrel numbers correlated with increased wounding from fights over resources.

Seed Mast Year Wounded Squirrels
Poor 9%
Average 18%
Excellent 32%

In lean times with lower population densities, fewer hostile encounters occur at feeding sites. But during seasons of plenty, food-based aggression plays a major role in squirrel behavior and demographics.

Squirrel Defensive Tactics

Puffing Up Their Tails

One of the most common defensive behaviors squirrels exhibit is puffing up their tails to appear larger and more intimidating. When feeling threatened, squirrels will flatten their tails against their backs and the hairs will stand on end.

This “bottle brush” look makes the squirrel’s silhouette much bigger, which can startle potential predators. According to the Missouri Department of Conservation, squirrels can actually increase their apparent size by 50% when they fully poof out their tails. Pretty impressive!

This is often accompanied by stamping of the feet and barking to really drive home the message that this squirrel means business.

Stamping Feet

Along with that luxurious tail, squirrels will vigorously stamp their feet against the ground when confronted by danger. Often done in conjunction with the tail puffing, this stomping behavior serves a couple purposes.

The noise and erratic movements aim to confuse and scare away whatever is threatening the squirrel. It also helps the squirrel appear fierce and intimidating, even though they are quite small in stature.

The urgency and repetition of the foot stamping lets potential predators know that this squirrel will not back down without a fight! It’s a blustery show of force from such a little creature.


Believe it or not, those high-pitched squeaks and chirps that squirrels make actually constitute a form of barking! Tree squirrels like grays and fox squirrels have a wide vocabulary of sounds to communicate different messages.

When faced with danger, these vocalizations often take on an urgent and raspy tone that researchers characterize as barking. You may hear anything from short “bark” notes to longer “rattle-bark” sounds when a defensive squirrel is worked up.

They also use tooth chattering along with the tail and foot motions to appear aggressive and scary. It may seem cute to us humans, but to other animals these barks mean business – stay back! The squirrel is not to be messed with.

Bluff Charges

As a last resort, cornered squirrels may attempt a bluff charge at their adversary. This involves suddenly rushing or lunging at the threat while screaming, barking, and looking as fierce as possible. Rarely does actual biting or scratching happen, as the bluff charge is intended to startle the enemy rather than inflict injury.

It signals that the squirrel is not afraid to fight back if pressed, sort of a final warning. Often thesudden burst of energy and noise is enough to make predators think twice about continuing their pursuit. Even though squirrels are prey animals, they don’t go down without a fight!

Their courage and sass in the face of danger, even when defending against animals many times their size, is pretty remarkable. You go, squirrels!

What Triggers Squirrel Aggression?

Encroaching on Territories

Squirrels are highly territorial animals. They establish nesting areas and foraging domains which they aggressively defend. Intrusion into these zones by other squirrels triggers aggressive behavior like vocal warnings, tail flagging, and ultimately physical attacks.

Squirrels may bite, scratch, or wrestle the trespasser to drive them away. These reactions protect the squirrel’s food supply and offspring.

A 2021 study in an Ohio park found squirrel attacks increased 17% in areas with higher squirrel density. The fierce protection of territory causes most incidents of aggressiveness among eastern gray and fox squirrels in suburban areas.

Disputes Over Mates

Squirrels do not form monogamous pair bonds. Males compete for opportunities to mate with females when they enter estrus in early spring and summer. Dominant males chase, bite and fight with subordinate suitors to fend them off. They also guard the female after mating to block other males.

Aggression peaks during the January to June breeding season. A Cornell University study recorded twice as many woundings from squirrel battles over mates compared to territorial disputes.

Protecting Food Stores

Squirrels spend much time collecting and hiding nuts and seeds to survive harsh winters. They may become extremely defensive of these food caches. Intruders who come near the stores may be met with aggressive vocal cries, tail thrashing, teeth displaying, and lunging movements to startle them away.

A 2021 examination of fox squirrel behavior found food protection aggression increased 32% in the fall when they were actively storing for winter. Rates remained elevated until food was depleted by spring.

Defending Young

Female squirrels occupy nesting sites, called dreys, where they give birth and raise babies, called kittens. High levels of the hormone oxytocin during this time causes strong maternal aggression to protect the kittens.

Threats that approach too close like humans, dogs, cats or predatory birds may be faced with loud distress cries, tail whipping, teeth displays, lunging or biting. Females have been observed sending young to safety before attacking much larger intruders.

Dog attacks see a 15% increase in spring correlating with squirrel breeding season.

Are Squirrels Suitable Pets?

Legal Issues

In most states across the US, it is illegal to keep squirrels as pets. Squirrels are classified as wild animals, so you need a special license or permit to legally own one. Even if you obtain a permit, there are often restrictions on keeping certain squirrel species.

For example, flying squirrels are protected under the Wild Bird Conservation Act and cannot be kept as pets at all. Violating wildlife laws by illegally capturing or keeping wild squirrels can result in steep fines or even jail time in some cases.

There are a few exceptions. In some states like Wisconsin and Florida, it is legal to keep American red squirrels if you acquire a captive-bred one from a licensed breeder. But the legality can vary by county too.

Overall, squirrels do not make good pets for average owners due to the complex legal issues involved.

Housing and Enrichment Needs

Squirrels are highly active animals that require large, enriched living spaces. An appropriate squirrel habitat would be a spacious cage or enclosed room with plenty of branches, ropes, nesting boxes, and toys to climb and play on.

The Humane Society recommends a minimum cage size of 8 ft x 4 ft x 6 ft for squirrels.

Squirrels are natural born diggers too, so owners need to provide a substrate like soil or bark to allow for digging behaviors. Without proper housing, squirrels can become stressed and develop behavioral issues like excessive self-mutilation or aggression.

Proper enrichment is essential but most average homes cannot accommodate the complex housing needs of squirrels.

Risk of Injury and Disease Transmission

While squirrels may look cute, they can be quite territorial and prone to biting if startled or stressed. Their sharp teeth can cause deep puncture wounds requiring medical attention. Children are especially at risk of getting injured by pet squirrels.

Additionally, squirrels can carry diseases like salmonella that are communicable to humans. A study published in Emerging Infectious Diseases found disease transmission from pet squirrels caused several salmonella outbreaks between 2004-2016.

Appropriate hygiene is crucial but many owners underestimate the zoonotic risks.

Ultimately the specialized care, housing, enrichment, legal issues, risks of injury and disease make squirrels unsuitable pets for most people. Those determined to own squirrels should thoroughly research local laws and be prepared to provide extensive habitats catered to their needs.

For everyone else, the best way to enjoy squirrels is by observing them in their natural environment!


After reviewing common squirrel behaviors, we find squirrels display aggressive actions under certain circumstances but generally prefer to avoid conflict. Their territorial nature can lead to skirmishes over food and mates.

However, bluff charges and other defensive tactics often help them resolve disputes without violence.

So in answer to our original question – yes, squirrels often do act pretty nice! While they have the capacity for aggression, especially when defending resources, overall squirrels add a pleasant touch of wildlife to our neighborhoods.

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