thumb|A dog barking
A bark is a sound most often produced by dogs. Other animals that make this noise include, but are not limited to, wolves, coyotes, foxes, seals, frogs and owls. Bark is also a verb that describes the sound of many canids. Researchers at the University of Massachusetts Amherst and Hampshire College have defined a bark as a short, abrupt vocalization that is relatively loud and high-pitched, changes in frequency, and often repeats rapidly in succession.
In dogs
Dog barking is distinct from wolf barking. Wolf barks represent only 2.4% of all wolf vocalizations, in warning, defense, and protest. In contrast, dogs bark in many social situations, with acoustic communication in dogs being described as hypertrophic. While wolf barks tend to be brief and isolated, dog barking is often repetitive.
One hypothesis for why dogs bark more than wolves is that dogs developed vocal communication as a result of their domestication. Domesticated breeds show vast physical differences from their wild counterparts, an evolution that suggests neoteny, or the retention of juvenile characteristics in adults. The behaviour of adult dogs also shows puppy-like characteristics: dogs act submissive, whine, and bark often.
The frequency of barking in dogs compared to wolves could also be the product of the different social environments of dogs. From a young age, humans may be among a dog's primary social contacts, an environment that presents different stimuli than would be found by wolves in the wild. Intruders may frequent the boundaries of a captive dog's territory, thus triggering the bark response as a warning. Dogs also live in densely populated urban areas, allowing for more opportunities for socialization. For example, kennelled dogs may have increased barking due to a desire to facilitate social behaviour. Dogs' close relationship with humans also renders dogs reliant on humans, even for basic needs. Barking can be used as a way to attract attention, and any positive response exhibited by the owners reinforces the behaviour. For example, if a dog barks to get food and the owner feeds it, they are conditioned to continue said behaviour.
Types
The purposes of barking by domestic dogs is a controversial topic. While barking is suggested to be "non-communicative", data suggests that it may indeed be a means of expression that became increasingly sophisticated during domestication. Due to the lack of consensus over whether or not dogs communicate using their barks, not much research has been done to categorize the different types of barking in dogs. Some existing research has been criticized by Feddersen-Petersen as "lack[ing] objectivity". Using sonographic methods, Feddersen-Petersen identified several distinct types of barks, then analysed them for meanings, functions, and emotions. He separated dog barks into subgroups based on said sonographic data:
{| class="wikitable"
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! Bark !! Characteristics !! Behavior
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| Infantile bark (pup yelp) || Harmonic || Emitted spontaneously in protest or as a distress call
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| Harmonic play bark || Mixed sounds involving "concurrent superimposition" of growls, noisy bark || After barking, play behavior was often observed.
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| "Christmas tree" bark || Sonogram displayed "Christmas tree" effect. There is a "sequential loss of overtones". || Seen in German Shepherds and Alaskan Malamutes.
|-
| Noisy overlappings || Short, overlapping sounds || Seen in poodles.
|-
| Pure harmonic sound || || Often accompanied with play behavior.
|-
| Specific vibrato-growl || ||
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| Noisy bark || || Agonistic contexts only. Seen in Alaskan Malamutes.
|-
| Play-solicited barks || Often combined with growls, other bark subunits. || Matched with play behavior
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| Noisy play bark || Harsh, short sound. Low-pitched, with an extremely short, sharp rise. || Associated with more harsh play-fighting seen often in American Staffordshire Terriers and Bull Terriers. "Often show[ed] changeovers to aggressive interactions."
|-
| Threat bark || Short, low-pitched sound. ||
|-
| Warning bark || Short, low-pitched sound. ||
|}
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Turid Rugaas classifies barks thusly in her book Barking: The Sound of a language:
{| class="wikitable"
|-
! Bark !! Description
|-
| Excitement bark || It's a high-frequency hysterical-sounding bark. It can be accompanied by whining. One observes it when a hyper dog is highly aroused, like when people come home or the dog is going out in a car or there is another dog in sight.
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| Warning bark || It's a single "woof" sound meant to convey a warning. It's not going to be loud and prolonged. But it has an important message. Often people don't even notice this bark. So a dog feels like his/her message was ignored and then takes charge of the situation. This can result in aggression or a full-fledged barking problem. Acknowledge warning barks.
|-
| Fear barking || This is a long series of high-pitched barks, similar to excitement barking. But you can sense the dog's fear. The bark could end in a howl. A classmate of mine once explained this: "When a dog has fear in his voice, you just know it!" What a dog is afraid of is hard to predict and sometimes hard to understand. But it's important to accept it and respect it. A dog will take time to overcome his/her fears. It's important to note what s/he is expressing fear towards and give him a chance to get away from it.
|-
| Guard bark || This type of barking occurs when a dog feels the need to defend himself/herself against a perceived threat. The barking is often accompanied by plenty of growling. Due to the growling, it is often mistaken for aggression or dominance. But the need to defend oneself comes from a fear. It is a pity when such dogs are then reprimanded or dominated. It pushes them further into a corner and can force them to go into a shell or snap back. A dog that feels a need to guard has to be removed from that position immediately. Further training can help the dog learn to be less fearful in such situations.
|-
| Frustration bark || This is a monotonous bark that keeps repeating and sometimes ends in a howl. It is born out of boredom or utter frustration. Such dogs are crying out for help. They need mental stimulation or need some serious reconsideration of their lifestyle. A behaviorist should be able to help in such a situation.
|-
| Learned bark || Such barking can be recognised by looking at the dog. The dog will bark and then keep looking back at people to see what reaction he/she is getting out of the people. He has learned that barking gets him a certain reaction. Giving him any reaction, including yelling at him, gives him exactly what he is planning on getting. Work with a behaviorist to correct this behavior. But do not reprimand him. That will make matters worse.
|} -->Not all breeds demonstrate every subgroup of barking. Instead, there is significant variance in vocalization between different breeds. Poodles show the least of all barking subunits. Barking in wolves was observed as less diverse. For example, wolf barks are rarely harmonic, tending instead to be noisy.
There is some evidence that humans can determine the suspected emotions of dogs while listening to barks emitted during specific situations. Humans scored the emotions of dogs performing these barks very similarly and in ways that made sense according to the context. In one example, when subjects were played a recording of a dog tied alone to a tree, a situation in which one could infer that the dog would be distressed, the human listeners tended to rank the bark as having a high level of despair. Some suggest that this may be evidence that dog barks have evolved to be a form of communication with humans, since humans can determine a dog's needs by listening to their vocalizations. Further studies have found that the acoustic structure of a bark "[varies] considerably with context." These studies suggest that barks are more than just random sounds, and hold some communicative purpose.
As noise pollution
Causes and solutions
thumb|upright|Signaling to a dog with the palm of the hand is prescribed as a way to address a dog that is alert barking.
Different kinds of barking require different approaches to reduction.
Common approaches
thumb|upright|Splitting is prescribed as a way to address a dog that is alert barking.
Barking is a normal behaviour for dogs. What counts as excessive barking is a subjective idea. Excessive dog barking can be a nuisance and a common problem that dog owners or their neighbors may face. Excessive barking indicates an underlying problem, a trigger or the dog lacking exercise or mental stimulation. Reasons for excessive barking can be, among others, pain, fear, boredom, frustration, separation anxiety or territorial behaviour (warning about potential threats). Turid Rugaas explains that barking is a way a dog communicates. She suggests signaling back to show the dog that the dog's attempts to communicate have been acknowledged and to calm a dog down. She suggests the use of a hand signal and calming signals called 'splitting'.
- Seeking professional advice from local organizations, dog trainers, or veterinarians.
If all other methods have been tried, a last effort is using a bark collar. These collars might release an unpleasant smell or mild to painful shock. Various bark collars have been praised and criticized; some are considered inhumane by various people and groups. Critics consider them torturous and compare their use to electrocution. However, most Societies for the Prevention of Cruelty to Animals agree that in a last resort an electric collar is better than euthanasia if it comes to an ultimatum, for a stubborn dog that will not stop any other way. Most agree that understanding the communication and retraining by reward is the most effective and humane method.
Surgical debarking
The controversial surgical procedure known as 'debarking' or 'bark softening' is a veterinary procedure for modifying the voice box so that a barking dog will make a significantly reduced noise. It is considered a last resort by some owners claiming that it is better than euthanasia, seizure, or legal problems if the matter has proven incapable of being corrected any other way.
Debarking is illegal in many European states and is opposed by animal welfare organizations.
Breeds
The Huntaway is a working dog that has been selectively bred to drive stock (usually sheep) by using its voice. It was bred in New Zealand, and is bred based on ability rather than appearance or lineage.
Naturally "barkless" dog breeds
Compared to most domestic dogs, the bark of a dingo is short and monosyllabic. During observations, the Australian dingo's bark has a small variability; sub-groups of bark types, common among domestic dogs, could not be found. Furthermore, just 5% of the observed vocalizations consisted of barking. Australian dingoes bark only in swooshing noises or a mixture of atonal and tonal. Also, barking is almost exclusively used for giving warnings. Warn-barking in a homotypical sequence and a kind of "warn-howling" in a heterotypical one have also been observed. The bark-howling starts with several barks and then fades into a rising and ebbing howl and is probably, similarly to coughing, used to warn the puppies and members of the pack. Dingoes also emit a sort of "wailing" sound, which they use most often when approaching a water hole, probably to warn already present dingoes. According to current knowledge, it is impossible to get Australian dingoes to bark more often by making them associate with other domestic dogs. However, Alfred Brehm reported a dingo that learned the more "typical" form of barking and knew how to use it, while its brother did not. Whether dingoes bark or bark-howl less overall is unknown.
The extinct Hare Indian dog of northern Canada was not known to bark in its native homeland, though puppies born in Europe learned how to imitate the barking of other dogs. When hurt or afraid, it howled like a wolf, and when curious, it made a sound described as a growl building up to a howl.
The Basenji of central Africa produces a yodel-like sound due to its unusually shaped larynx. This trait also gives the Basenji the nickname "Barkless Dog".
In other animals
Besides dogs and wolves, other canines like coyotes and jackals can bark. Various bird species produce vocalizations that include the canonical features of barking, especially when avoiding predators.