Territorial Behavior in Dogs: Do Dogs Defend a Territory?

1. Why the Question Matters

1.1 A Familiar Scene

A delivery van stops in the street. Before the driver has opened the gate, the dog is at the fence, barking and running along the boundary. The driver drops the parcel and leaves, and the dog goes quiet. Most owners would call this territorial behavior: the dog is defending its home.

The label carries more than a description. It implies a motivation (defense of an area), a comparison (wolves defend territories too) and often a recommendation (the owner has to take charge of the house). Each of these can be checked against research, and they do not hold up equally well.

The same barking at the fence can mean different things. One dog may be frightened by an approaching stranger and try to increase distance. Another may be highly aroused by movement in the street. A third may have learned that barking is followed by the stranger leaving. From the outside, these dogs can look very similar. The behavior has to be read in context.

1.2 What This Article Covers

The article starts with the concepts ecologists use to describe space use, then reviews territorial defense in wolves and free-ranging dogs. The main part deals with household dogs: how so-called territorial aggression is measured, how it relates to fear, what breed, genes, castration and learning contribute, and how the behavior can be read in context.

2. Territory, Home Range and Core Area

2.1 The Classic Distinction

The concepts most often used in mammal ecology go back to Burt. As quoted in later reviews, Burt defined a territory as "any defended area" and contrasted it with the home range, "that area traversed by the individual in its normal activities of food gathering, mating and caring for young" (Burt, 1943, as quoted by Potts & Lewis, 2014). Another review puts it this way: a territory is an area whose exclusive ownership, or at least priority of use, individuals attempt to maintain, whereas a home range merely represents how an animal has occupied a given region of space (Burt, 1943, as quoted by Giuggioli & Kenkre, 2014).

The key difference is defense. A home range describes where an animal goes; a territory describes an area it tries to keep others out of. There can be territorial areas within a home range (Giuggioli & Kenkre, 2014). "Ownership" here is a technical term for exclusive or priority use, not a mental concept of possession.

2.2 How Space Use Is Measured

Modern studies rely mostly on GPS collars that record an animal's position at regular intervals. From these positions, researchers estimate a utilization distribution, a map of how intensively different parts of the area are used; in mathematical terms, a home range resembles such a distribution over time (Potts & Lewis, 2014). For dogs, two thresholds are commonly reported: the core home range contains 50% of the estimated use, the extended home range 95% (Molloy et al., 2017).

These numbers depend on how the data were collected. Home range estimates depend heavily on sampling frequency and on the time span of recording (Giuggioli & Kenkre, 2014), so studies with different collar settings are not directly comparable.

2.3 What Counts as Evidence of Territoriality

Because a territory is defined by defense, GPS data alone cannot show it. Evidence comes from other observations: aggressive encounters between neighboring groups, where they happen, how animals respond to intruders and where they place scent marks. In territory models, scent marks play a central role, and territories built on marking change slowly over time (Potts & Lewis, 2014). Even marking is indirect evidence, because marks can serve several functions at once.

The strongest evidence therefore combines several kinds of data: where animals live, where they fight, who wins and who takes part. For wolves, such combined data exist. For free-ranging dogs, they exist for a few populations. For household dogs, as later sections show, they are largely missing.

3. Wolves: Territoriality in the Strict Sense

3.1 Deaths at the Edges

Gray wolves are among the best-documented territorial mammals. In some species, including gray wolves, intraspecific strife is described as the leading cause of natural mortality (Cassidy et al., 2017).

A radio-telemetry study in north-eastern Minnesota from 1968 to 1992 recorded 22 territorial wolves killed by other wolves (Mech, 1994). Of these, 23% were killed precisely on the borders of their estimated territories, 41% within 1.0 km of the estimated edge (about 16% of the mean territory radius) and 91% within 3.2 km (about 50% of the mean radius). The author described this as the first report of intraspecific mortality along territorial boundaries. Conflicts between neighboring packs were concentrated where their areas met, and they were fatal. The territories were estimated, and the data come from one population.

3.2 Who Wins: Pack Size and Composition

A long-term study in Yellowstone National Park analyzed 121 aggressive interactions between wolf packs from 1995 to 2010 (Cassidy et al., 2015). Relative pack size improved the odds of displacing the opponent, but packs with relatively more old members (older than six years) or more adult males had higher odds of winning despite a numerical disadvantage. Some individuals, the authors concluded, are more valuable than others in interpack conflict.

Location relative to the packs' territories had no effect on the outcome (Cassidy et al., 2015). This does not contradict the Minnesota data, because one study looked at where wolves died and the other at which pack won. The two results should not be merged into a rule about "home advantage". The Yellowstone population was reintroduced, and only the abstract was available for this review.

3.3 Who Defends: Males and Division of Labor

A second Yellowstone analysis covered 292 inter-pack interactions from 1995 to 2011, more than 5,300 days of observation and 534 wolves (Cassidy et al., 2017). All wolves were more likely to chase rivals when their pack outnumbered the opponent. Males were more likely than females to chase rival packs and male lone intruders, and male age correlated positively with chasing. Gray-colored wolves were more aggressive than black ones, and males and gray wolves had higher cortisol. The authors interpreted this as a division of labor in resource and territory defense. Territorial defense in wolves is thus a group activity in which individuals contribute differently, not a uniform reaction of every pack member. The study is observational, and the cortisol link is correlational.

3.4 Scent Marks at Crossroads

In a 12,000 ha natural park in north-western Spain, researchers collected 311 wolf scats along roads between 1998 and 2000 (Barja et al., 2004). Scats were deposited preferably at crossroads (60.1%) and on conspicuous substrates (72.1%), more often at intersections connecting distant territories, and more at larger crossroads. The authors concluded that scats have an important function in territorial marking. That function is inferred from placement, not from the responses of other wolves.

3.5 The Wolf Pack Is a Family

Popular explanations of territorial behavior in dogs often borrow the image of an "alpha" wolf defending its land. That image is outdated. A literature review combined with 13 summers of observation on Ellesmere Island concluded that the prevailing alpha view stems mostly from non-natural assortments of captive wolves (Mech, 1999). The typical wild pack is a family in which the parents guide activities in a division of labor, with the female predominating in pup care and defense and the male in foraging and provisioning (why the dominance concept fails as an explanation for dog behavior). The wolf data support territorial defense as a family group activity with real costs, not as an expression of rank.

4. Free-Ranging Dogs: Space Use and Group Conflict

4.1 Free-Ranging Dogs Are Not Wild Wolves

Free-ranging dogs are often treated as a window into what dogs do "naturally". They are a better model than captive wolves, but they are not wild wolves. Most live close to people and depend on them, and their social organization differs between places (how dogs and wolves differ in social behavior).

4.2 Home Ranges from GPS

In four remote Aboriginal communities in the Northern Territory of Australia, 58 dogs wore GPS collars for one to four days, with positions every one to three minutes (Molloy et al., 2017). The median core home range was 0.27 ha, the median extended home range 3.1 ha. Ranges differed between communities, and coastal dogs traveled more per day. Range size was associated with sex and neuter status; entire males roamed more than neutered females, and dogs in poor or fair body condition had larger core ranges. Recording periods were short and limited to one season.

Across eight Aboriginal and Torres Strait Islander communities, GPS data from 135 dogs showed core home ranges of 0.17 to 2.33 ha and extended home ranges of 0.86 to 40.46 ha (Dürr et al., 2017). Non-castrated males had the largest ranges, followed by neutered females, and dogs roamed more before the wet season than after it.

A study across four countries fitted 773 dogs in Chad, Guatemala, Indonesia and Uganda with georeferenced contact sensors and GPS recording for about 60 hours on average (Warembourg et al., 2021). Eighty-seven dogs were excluded from the home-range analyses because of insufficient recordings, too few GPS positions or missing data. Median core home ranges were similar: 0.30, 0.33, 0.30 and 0.25 ha; median extended ranges were 7.7, 5.7, 5.6 and 5.7 ha. The predictors of roaming varied by country, and sex was a predictor only in Chad. The authors concluded that roaming is closely related to the owners' socioeconomic context and local environment, and that free-roaming dogs strongly depend on humans.

On the Tiwi Islands, only 9.8 ± 2.5% of an estimated 326 ± 52 dogs were confined to a house yard (Sparkes et al., 2014). Seven-day activity ranges varied from 9.2 to 133.7 ha, males ranged more widely, and entire females and neutered males had more contacts with other dogs than spayed females or entire males. Because the deployments lasted only seven days, the authors did not calculate traditional home ranges and used the term activity range instead.

4.3 What Home Range Data Do Not Show

Many free-roaming village dogs spend most of their time in a fraction of a hectare around their owner's house. What these studies do not show is defense. None measured whether dogs kept other dogs out of their core areas, and the Tiwi dogs contacted each other frequently (Sparkes et al., 2014). Calling a small core area a territory would require evidence of defense that was not collected. A home range result describes how a dog uses space, and nothing more.

4.4 Group Defense in Rome

The clearest evidence for group defense of space in dogs comes from free-ranging dogs in Rome. Conflicts between neighboring groups were regular events with recognizable participants and predictable escalation and withdrawal, and the groups were stable and showed coordinated collective behavior (Bonanni, Valsecchi & Natoli, 2010). How these groups are organized is reviewed elsewhere (how free-ranging dogs organize their social life).

A study of naturally occurring conflicts in a suburban free-ranging population found that the probability of at least one pack member approaching opponents aggressively increased as the ratio of rivals to companions decreased, while the probability that more than half of the pack withdrew increased with that ratio (Bonanni et al., 2011). Assessment improved with larger asymmetry when at least one pack had more than four members. The dogs behaved as if they compared opponents with companions before committing to a fight. The study is observational, and its sample size could not be verified for this review.

4.5 Boundaries and Scent in India

In Katwa, India, a 12-month study followed 21 free-ranging dogs in four neighboring groups (Pal, 2015). Cooperative defense occurred mainly at territory boundaries, males showed more agonistic behavior there, and in most cases more than one dog participated in conflicts. The group home range was largest in the late monsoon and winter. The sample was small and from one town.

In a pack of free-ranging dogs, scent marking was used to form a "property line" and to threaten rivals during conflicts; both sexes also marked in relation to rank and probably to relocate food or maintain possession, and the authors stressed that these functions are not mutually exclusive (Cafazzo et al., 2012). A field experiment in India presented scent marks from dogs of different sex and group at strategic spots in a territory (Biswas et al., 2025). Both sexes were more interested in marks than in controls, overmarking was mainly shown by males, especially toward male marks and marks of neighboring groups, and neighboring-group male scents evoked the most distinct reactions. The authors concluded that marks mediate both territorial defense and intrasexual competition (what scent marking communicates between dogs).

Group life is not only conflict. A five-year study of 23 mother-litter units in 15 groups documented widespread allo-parenting, with putative fathers playing with and protecting pups more (Paul & Bhadra, 2018). Protecting pups is a form of defense, but not defense of an area.

4.6 Variation Between Populations

The literature does not support a general statement that "dogs defend territories". Stable packs with coordinated intergroup conflicts were described in Rome (Bonanni, Valsecchi & Natoli, 2010), smaller family-based groups with boundary defense in one Indian town (Pal, 2015), and small home ranges tied to the owner's household, with no measure of defense, in village populations (Warembourg et al., 2021). Dogs are capable of group defense of space under some ecological conditions. Whether a population is territorial depends on its ecology, group stability and dependence on humans.

5. Household Dogs: What "Territorial Aggression" Means in the Data

5.1 A Label for a Place

For pet dogs, "territorial aggression" usually refers to aggression at or near the home: barking and lunging at the fence or window, threatening visitors or rushing at delivery workers. The label names where the behavior happens, not why (why aggression labels describe contexts rather than causes). The conditions that define territoriality in wolves are mostly absent: there are no neighboring rival groups and no evidence that the dog maintains an exclusive area against other dogs over time. What remains is a dog reacting to people and dogs at a familiar place.

5.2 How the C-BARQ Captures It

Much of the large-scale research uses the Canine Behavioral Assessment and Research Questionnaire (C-BARQ). In its validation study, owners of 1,851 dogs plus 203 behavior-clinic dogs answered 152 items, and factor analysis yielded 11 factors from 68 items, accounting for 57% of the common variance; 200 of the 203 clinic dogs could be assigned to seven diagnostic categories matching seven factors (Hsu & Serpell, 2003).

The item list published with a later study shows where home situations end up (Farhoody et al., 2018). "When mailmen or other delivery workers approach your home", "when strangers walk past your home while your dog is outside or in the yard", "when joggers, cyclists, rollerbladers, or skateboarders pass your home", "when an unfamiliar person approaches you or another member of your family at home", "toward unfamiliar persons visiting your home" and "toward unfamiliar persons approaching the dog while s/he is in your car" all belong to stranger-directed aggression. "Toward unfamiliar dogs visiting your home" belongs to dog-directed aggression.

In the sources reviewed here, there is no separate validated territorial factor. What owners call territorial is measured as aggression toward strangers, with home contexts mixed in with the car and other situations. Findings on stranger-directed aggression therefore apply to a composite, not specifically to the fence or the door.

5.3 How Common It Is

In a UK owner survey, aggression toward unfamiliar people entering the house was reported in about 7% of dogs and toward family members in about 3% (Casey et al., 2014). Co-occurrence across contexts was low, and the measured variables explained less than 10% of the variance. Use of positive punishment or negative reinforcement was associated with more reported aggression toward strangers. The exact sample size and effect sizes could not be checked against the primary source.

In 13,700 Finnish dogs, aggression toward family members and toward strangers was each reported in 6%, and only 9% of aggressive dogs were aggressive toward both (Salonen et al., 2020). In a UK survey on dog-directed aggression, 22% of owners reported aggression toward unfamiliar dogs and 8% toward household dogs, with low concordance between dog- and human-directed aggression (Casey et al., 2013). Aggression is often specific to a context and target, one more reason to treat "territorial aggression" as a description of a situation, not a trait.

5.4 Bites at Home and on Property

In an online convenience sample of 484 bite victims, 66.1% of biting dogs were known to the victim (Oxley et al., 2018). Of 402 bites with a recorded location, 40.5% occurred on private property, 27.4% in public and 16.7% on commercial premises; 0.7% occurred at a public-private border, such as an arm put through a fence. Of 398 described situations, 34.7% involved interacting with the dog and 20.1% walking or walking past; entering or leaving a house, room, property or garden accounted for 6.5%, and delivering post, newspapers or leaflets for 3.0%. Most bites were minor: 62.3% of victims sought no medical treatment. The sample was self-selected, contexts were described by victims, and the dogs' motivation is unknown (what is known about bites by familiar dogs).

In a Cheshire community survey of 694 respondents in 385 households, 24.78% had ever been bitten, with an incidence of 18.7 per 1,000 per year; 54.7% of bites came from a dog never met before (Westgarth et al., 2018). Owners of several dogs were 3.3 times more likely to report having been bitten. Whether these bites occurred on the dog's property was not analyzed in the parts available for this review.

A clinic-based study in Kingston, Jamaica (660 dogs) and San Francisco (452 dogs) found that dogs acquired for companionship were more likely to have bitten than dogs acquired for protection (relative risk 1.66; 95% CI 1.02 to 2.70), and that routinely allowing the dog to be present with visitors was associated with biting (Messam et al., 2008). Other risk factors differed between the cities: sleeping in a family member's bedroom was a risk factor in Kingston but not in San Francisco, and leaving the yard unaccompanied in San Francisco but not in Kingston. The authors emphasized that associations differ by culture. The protection-dog finding runs against the guard-dog stereotype, but it needs care, because dogs kept for protection may be more restricted and therefore less exposed to situations in which bites happen.

6. Fear and Stranger-Directed Behavior

6.1 Aggression and Fear of Strangers Go Together

If the household version is mostly stranger-directed aggression, the most consistent correlate in the large surveys is fear. In a C-BARQ breed study, stranger-directed aggression correlated with stranger-directed fear in both samples: rs = 0.357 (n = 1,275) and rs = 0.409 (n = 3,216), both P < 0.0001 (Duffy et al., 2008). These are moderate correlations: dogs rated more aggressive toward strangers tended to be rated more fearful of them, not every aggressive dog is fearful.

6.2 Fear as the Strongest Correlate

A study of Finnish purebred dogs analyzed 9,270 dogs, 1,791 with frequent aggression toward people (Mikkola et al., 2021). The items included growling or snapping when a stranger tried to touch the dog "in its home or outside". Older age, male sex, small size, no conspecific company, being the owner's first dog, breed and fearfulness were associated with higher odds. Fearfulness was the strongest: high versus low fearfulness had an odds ratio of 5.181 (95% CI 4.525 to 5.917), moderate versus low 1.931 (1.667 to 2.237). The authors could not separate fear-related from other aggression, considered it possible that most dogs showed fear-related aggression, and did not analyze the home context.

In the larger Finnish sample, fearful dogs were 3.2 times more often aggressive than non-fearful dogs, which the authors interpreted to mean that aggression is commonly motivated by fear (Salonen et al., 2020). That is an interpretation of co-occurrence, not a measurement of motivation (how fear and anxiety work in the dog's brain).

6.3 Where Social Fear Comes From

In 6,000 Finnish dogs, fear of conspecifics or unfamiliar people was associated with urban living, poor puppy socialization, infrequent training and activities, small size, female sex and neutering, with breed differences (Puurunen et al., 2020). The design was cross-sectional, so direction is not established, but fear of strangers has developmental and environmental correlates, not only genetic ones.

6.4 Correlation Is Not Motivation

A dog barking and lunging at the fence cannot simply be assumed to be a confident defender. In many dogs, the behavior may be distance-increasing; in others, a mixture of approach and avoidance, or high arousal without much fear. No study reviewed here tested motivation directly at the home boundary, and inferring emotion from behavior always involves interpretation (why behavior is not a direct readout of emotion). The cautious conclusion is that household territorial behavior is often fear-related, and that this should be considered before assuming confident defense.

7. Barking at Strangers

7.1 Barks Differ by Context

Barking is the most common part of what owners call territorial behavior. A theoretical paper argued against the view that barking is nonfunctional, proposing that bark structure varies predictably with context (Yin, 2002). Barks of ten dogs in a disturbance situation were harsh, low in frequency and little modulated, whereas barks during isolation and play were higher and more tonal (Yin & McCowan, 2004). What the disturbance situation consisted of could not be verified here.

With barks of Mudi dogs recorded in staged situations, including a stranger at the gate, human listeners categorized the situations "high above chance" (Pongrácz et al., 2005). Low, harsh barks with short intervals were typical of the stranger and fight situations (Pongrácz, Molnár & Miklósi, 2006). The barks came from one breed, and the situations were staged (what barks, growls and whines communicate).

7.2 Who Is the Bark For?

A review concluded that barking provides information for humans about the dog's inner state, although there are few indications that barking is used for communication between dogs (Pongrácz, Molnár & Miklósi, 2010). This suggests a hypothesis: fence barking may work as much as a signal to the household as to the stranger. Because barks recorded in stranger situations are acoustically distinct, they may at least inform people that something unusual is happening. No study reviewed here tested whom fence barking is addressed to, and the hypothesis should not be treated as a finding.

8. Breed, Genes and Sex Hormones

8.1 Breed Differences at Population Level

In the C-BARQ breed study, aggression was most severe toward other dogs, then unfamiliar people, then household members (Duffy et al., 2008). Dachshunds, Chihuahuas and Jack Russell Terriers scored high for serious aggression toward strangers and owners, Australian Cattle Dogs toward strangers, while Golden and Labrador Retrievers, Bernese Mountain Dogs, Brittany Spaniels, Greyhounds and Whippets were among the least aggressive. In Finland, aggression toward strangers was reported in 10.6% of Miniature Schnauzers but 0.4% of Labrador Retrievers (Salonen et al., 2020).

Duffy et al. (2008) also compared their rankings with expert rankings for "watchdog barking" (alerting to an intruder) and "territorial defense" (attacking an intruder), and found broad agreement with some divergent breeds. This is the only place in the household-dog sources where "territorial" appears as a ranked trait, and it comes from expert opinion. A genetic study of more than 14,000 dogs of 101 breeds found high among-breed heritability for 14 behavioral traits and 131 associated genetic variants near genes highly expressed in the brain (MacLean et al., 2019). The trait-specific heritability for stranger-directed aggression could not be verified for this review.

8.2 Little Predictive Value for the Individual

Breed averages say little about an individual. Duffy et al. (2008) noted that substantial within-breed variation suggests a major role for developmental and environmental factors, and that owner reports may be biased by breed stereotypes. In 18,385 surveyed and 2,155 genotyped dogs, most traits had heritabilities above 25%, but breed explained only about 9% of behavioral variation in individuals (Morrill et al., 2022). For "agonistic threshold", how easily a dog is provoked by frightening, uncomfortable or annoying stimuli, breed was almost uninformative. Encyclopedia rankings for "watchdog ability" and "friendliness towards strangers" both correlated with human sociability, but in opposite directions (how little breed predicts about an individual dog). "Guard breeds are territorial, others are not" is therefore not supported.

8.3 Castration and Territorial Aggression

The oldest study that measured territorial aggression specifically is a retrospective study of 42 adult male dogs castrated for behavior problems, with owners interviewed by telephone a mean of 27 months later (Hopkins, Schubert & Hart, 1976). Median age at castration was 24 months (8 months to 12 years). Problems included roaming (16 dogs), urine marking in the house (10), mounting (15), aggression toward other males (8), territorial aggression (8) and fear-induced aggression (4). The authors classified aggression into several types, including competitive, fear-induced, pain-induced, predatory, territorial, maternal and learned aggression, a scheme based on context rather than on measured motivation (mounting behavior in dogs).

Roaming was reduced in 90%, aggression toward other males declined in 62% of the eight affected dogs, and urine marking in the house declined in about half. Territorial aggression and fear-induced aggression were not altered (Hopkins, Schubert & Hart, 1976). The 62% is a share of dogs, not a 62% reduction. The authors themselves warned that their percentages were not an accurate representation of subjective owner reports. With eight dogs, no control group and recall data, the study shows only that castration did not obviously change territorial aggression in this small group (what testosterone does and does not do in aggression).

A C-BARQ study analyzed 13,498 surveys for aggression toward strangers (Farhoody et al., 2018). It found a low but significant increase in the odds of moderate or severe stranger-directed aggression in gonadectomized dogs, accounted for entirely by dogs gonadectomized at 7 to 12 months (26% more likely), and no association with aggression toward familiar people or dogs. In Finland, neutering was associated with social fearfulness (Puurunen et al., 2020). The directions are not consistent, and all data are cross-sectional or uncontrolled, but none supports castration as a treatment for territorial or stranger-directed aggression (what neutering changes in behavior and what it does not).

9. What Keeps the Behavior Going

9.1 The Mail Carrier Who Always Leaves

One feature of household territorial behavior is often overlooked: the stranger almost always leaves. The mail carrier walks on, the passer-by continues, the driver drives away. For the dog, every episode ends the same way, whether or not the barking had anything to do with it.

Learning theory offers a plausible mechanism. If barking is followed by the departure of something the dog finds threatening or unsettling, the departure may act as negative reinforcement, and over many repetitions the barking may become stronger and faster. This is a hypothesis. No empirical study of barking at mail carriers with a verifiable publication record was found, and how much learning contributes relative to fear, arousal or genetics is unknown.

9.2 Repetition, Sensitization and Arousal

Repeated exposure can lead to habituation or to sensitization, depending partly on stimulus intensity and the animal's state (when repetition calms and when it sensitizes). A dog watching a busy street all day may get used to it or become more reactive. Arousal can also accumulate: a dog that has barked at three passers-by within an hour may react more strongly to the fourth. Both ideas fit what is known about arousal and learning, but neither has been studied specifically at the home boundary.

Learning, fear and arousal are not competing explanations. A dog that is mildly afraid of strangers, highly aroused by movement and repeatedly experiences strangers leaving after it barks could be influenced by all three at once. Which of them dominates in a given dog cannot be read from the questionnaire data, and the answer may change as the behavior is repeated over months.

9.3 Explanations the Evidence Does Not Support

Four popular explanations are widespread, and the evidence reviewed here does not support them.

The household dog defends its pack's territory like a wolf: wolves defend territories at high cost against neighboring packs (Mech, 1994; Cassidy et al., 2015, 2017), and the wolf pack is a family (Mech, 1999). A pet dog does not live in a territorial group with neighboring rivals, and stable territorial groups are documented only in some free-ranging populations (Bonanni et al., 2011; Pal, 2015). The comparison does not transfer.

The dog barks at the fence to show it is the boss: no source reviewed here links fence or door barking to rank. These situations are measured as stranger-directed aggression (Farhoody et al., 2018), which correlates with fear (Duffy et al., 2008; Mikkola et al., 2021; Salonen et al., 2020).

The dog guards because it thinks it owns the house: no study has measured ownership beliefs in dogs. The biological concept of territory is defined by defense, not by a mental concept of possession (Burt, 1943, as quoted by Potts & Lewis, 2014). Describing what the dog does, where and toward whom is more accurate.

Castration cures territorial aggression: territorial aggression did not change in eight castrated dogs (Hopkins, Schubert & Hart, 1976), and the large C-BARQ study found no reduction in stranger-directed aggression (Farhoody et al., 2018).

10. Reading the Behavior in Context

10.1 The Same Bark, Different Meanings

No test tells which motivation lies behind a particular dog's behavior at the fence. What the research offers is a set of possibilities to keep apart: fear of strangers, high arousal triggered by movement or noise, behavior maintained by its consequences, frustration at a barrier, and in some dogs perhaps a confident threat. They are not mutually exclusive, and a dog can show different mixtures on different days. Posture, timing and recovery provide clues: a dog barking with its weight shifted back and ears pulled back may be in a different state from one standing tall with ears forward, although such signals are ambiguous on their own (how to read posture and facial signals in dogs).

In practice: It often helps to separate "how aroused is the dog?" from "how afraid is the dog?". A dog that barks at every movement, including familiar neighbors, may be dealing mainly with arousal, whereas a dog that reacts only to unfamiliar people and avoids them afterward may be dealing mainly with fear. This distinction comes from training practice, not from controlled studies, and many dogs show both.

10.2 Managing Access to the Boundary

If learning and repetition contribute, the number of repetitions matters. Reducing episodes does not change the underlying motivation, but it may keep the behavior from growing stronger while other work is done.

In practice: Limiting unsupervised access to the places where the behavior occurs, such as a fence along a busy footpath or a low window facing the street, often reduces episodes considerably. Window film, rearranged furniture or supervised garden time are simple ways to do this. This is an observation from practice, not from controlled studies.

10.3 Safety Around Visitors and Delivery Workers

Bites happen on private property, some when people enter a home or deliver something (Oxley et al., 2018), and routinely having the dog present with visitors was associated with biting (Messam et al., 2008). Neither study establishes cause, but the moment of entry deserves attention.

In practice: For dogs that react strongly to visitors or delivery workers, it is safer to have the dog behind a closed door or gate before the front door opens, and to let it meet visitors, if at all, once they are inside and calm. A letterbox outside the fence means no one has to reach into the dog's area. These measures come from practice and aim at preventing incidents, not at changing motivation.

10.4 Training and Aversive Methods

Training for reactions to strangers at home usually aims to change the dog's emotional response, for example by pairing a stranger at a distance with something pleasant and gradually increasing intensity while the dog stays below its reaction threshold (how desensitization and counterconditioning change emotional responses).

Aversive methods, such as startling or punishing the dog when it barks, can stop barking in the moment. The question is what the dog learns and at what cost. If the barking is fear-related, punishment adds an unpleasant experience to a situation the dog already finds threatening. In UK surveys, positive punishment or negative reinforcement was associated with more reported aggression toward strangers and dogs, although the design does not show cause and effect (Casey et al., 2013, 2014). Punishment can also suppress warning signals without changing the underlying state (what punishment can do to warning signals and behavior).

In practice: Training at the fence or door tends to progress more reliably when it starts at a distance or volume at which the dog can still notice the trigger and respond to the owner, with short sessions that end before the dog is overwhelmed. This is an observation from practice, not from controlled studies.

11. Summary at a Glance

A territory is a defended area, a home range the area an animal uses (Burt, 1943, as quoted by Potts & Lewis, 2014; Giuggioli & Kenkre, 2014). GPS studies of free-roaming dogs measure home ranges, often with core areas of a fraction of a hectare, but not defense (Molloy et al., 2017; Dürr et al., 2017; Warembourg et al., 2021).

Wolves are territorial in the strict sense: conflicts between packs can be lethal and are concentrated near territory edges, outcomes depend on pack size and composition, and males specialize in defense (Mech, 1994; Cassidy et al., 2015, 2017). Some free-ranging dog populations defend space as groups and assess opponent numbers, but social organization differs between populations (Bonanni et al., 2011; Pal, 2015; Biswas et al., 2025).

In household dogs, territorial aggression is measured as stranger-directed aggression, without a separate territorial factor (Farhoody et al., 2018). It correlates with fear (Duffy et al., 2008; Mikkola et al., 2021). Breed explains little individual variation (Morrill et al., 2022), and castration did not change territorial aggression in a small, uncontrolled study (Hopkins, Schubert & Hart, 1976). Learning through the repeated departure of strangers is plausible but untested. Pack, rank and ownership explanations are not supported.

12. Research Gaps and Critical Appraisal

12.1 No Study at the Boundary

The central gap is that no study reviewed here measured the motivation of household dogs at the home boundary directly, with standardized triggers and measures of fear, arousal and recovery. Everything said about motivation is inferred from questionnaire correlations and from other populations. Observational studies that record the behavior at real fences and doors over time, together with the dog's body language and recovery, would close much of this gap.

12.2 Owner-Report Measures

The household-dog data come almost entirely from owner questionnaires. The C-BARQ is validated (Hsu & Serpell, 2003), but its stranger-directed aggression subscale mixes home contexts with others, and owner reports are open to bias and breed stereotypes (Duffy et al., 2008; Morrill et al., 2022). The Finnish studies could not separate fear-related from other aggression (Mikkola et al., 2021), and correlations of 0.36 to 0.41 leave much variation unexplained.

12.3 Small and Uncontrolled Castration Data

The only study that measured territorial aggression before and after castration had eight such dogs, no control group and retrospective telephone recall (Hopkins, Schubert & Hart, 1976). The larger C-BARQ data are cross-sectional (Farhoody et al., 2018). A controlled study is missing.

12.4 Short GPS Periods

The GPS studies recorded one to seven days in one or a few seasons (Molloy et al., 2017; Sparkes et al., 2014; Warembourg et al., 2021). Because estimates depend on sampling frequency and duration (Giuggioli & Kenkre, 2014), the reported ranges are snapshots, and none measured defense.

12.5 Few Populations

Evidence for group defense in free-ranging dogs comes mainly from Rome and India. The Indian boundary study included 21 dogs in one town (Pal, 2015), and sample sizes of some key studies could not be verified (Bonanni et al., 2011; Biswas et al., 2025). The wolf data come from two regions, one with a reintroduced population (Cassidy et al., 2015, 2017).

12.6 Bite Data Without Motivation

Bite surveys used convenience or community samples and victims' descriptions (Oxley et al., 2018; Westgarth et al., 2018). They show where bites happen, not why. Peer-reviewed data on bites to mail carriers with a verifiable publication record were not found.

13. Conclusion

Do dogs defend a territory? Some do. Free-ranging dogs in stable groups have been observed defending space against neighbors, assessing opponents and marking boundaries, much as wolves do. That is territoriality in the biological sense, documented in a few populations.

The household dog barking at the fence is a different case. Research measures this behavior as aggression toward strangers at a familiar place, and its most consistent correlate is fear. Breed contributes at population level but predicts little for the individual, castration does not appear to change it, and learning through the repeated departure of strangers is plausible but untested. The household version is better described as stranger-directed behavior at a familiar place, often related to fear or arousal and sometimes maintained by learning. Pack, rank and ownership explanations are not supported. The same barking can mean different things, and reading it in context is more useful than a single label (how to handle barking at the fence, the window and the door).

Key Insights (Takeaways)

• A territory is a defended area, a home range the area an animal uses; GPS studies of free-roaming dogs measure home ranges, not defense (Burt, 1943, as quoted by Potts & Lewis, 2014; Warembourg et al., 2021).

• Wolves are territorial in the strict sense: 91% of 22 wolves killed by other wolves in Minnesota died within 3.2 km of the estimated territory edge (Mech, 1994).

• Some free-ranging dogs defend space as a group and weigh opponents against companions before attacking or withdrawing, but populations differ (Bonanni et al., 2011; Pal, 2015).

• In pet dogs, the situations called territorial are measured as stranger-directed aggression; no separate territorial factor appears in the sources reviewed (Farhoody et al., 2018).

• Stranger-directed aggression correlates with fear of strangers, and fearfulness is the strongest correlate of aggression toward people in large surveys (Duffy et al., 2008; Mikkola et al., 2021).

• Breed explains about 9% of individual behavioral variation (Morrill et al., 2022), and territorial aggression did not change after castration in eight dogs (Hopkins, Schubert & Hart, 1976).

• Learning through the repeated departure of strangers is a plausible but untested mechanism; pack, dominance and ownership explanations are not supported.

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