Connect with Animal Communication
By Cecile Ashen-Young
Communication is an important part of the behavioural repertoire of all animals. It is an intrinsic part of much of their social behaviour, facilitating social cooperation and conflict resolution (Turner & Bateson, 2000). In fact, it has been suggested that the primary function of animal communication is the manipulation of the behaviour of the receiver by the signaler in social interactions (Overall, 1997).
Communication is a multisensory process, and the most common modalities used to detect communication signals are hearing, vision, and smell/taste. While humans tend to concentrate on and readily perceive acoustic and visual signals, both dogs and cats use acoustic, visual, and olfactory signals to convey and receive information (Bolhius & Giraldeau, 2005). By better understanding how our dogs and cats communicate, we have the opportunity to use communication to optimize their welfare and quality of life.
Acoustic signals are an important communication tool used by both dogs and cats to transmit general messages over a range of distances and in different contexts. Acoustic signals are propagated at intermediate speeds that depend on the medium through which they are transferred (e.g. air temperature and humidity). They are always transitory, and the slow speed of sound through air will influence how the signal is perceived by the receiver and other animals in the vicinity (Bolhuis & Giraldeau, 2005).
The acoustic signals used by dogs are commonly categorized into different types of vocalizations that includes the bark, grunt, growl, and whimper/whine (Siniscalchi et al., 2018). The communicative function of each of these acoustic signals is quite varied, depending on the context in which the signal is used. The bark is used in defense (of territory) or as a warning, in play, as a greeting or a call for attention, and as a lone call. The grunt is used in greeting or to signal contentment. The growl is used as a defense warning or threat signal, and in play. The whimper/whine is used a submission signal, in greeting, as a call for attention, in defense, and as a pain signal (Bradshaw & Nott, 1995).
The acoustic signals used by cats also vary widely in form and function. Their vocalizations are categorized according to how the sound is produced. Murmur patterns are produced with a closed mouth and are used to seek out or initiate contact, and in greeting. Vowel patterns are produced when the mouth is open and then gradually closed and are used in greeting, and in sexual and aggressive contexts. Strained-intensity patterns are produced with a wide-open mouth and are used in defense and to signal aggression or fear and pain (Turner & Bateson, 2000).
For both species, some aspects of acoustic communication may have been affected by selection pressure, in other words, as a result of their adaptation to the human social environment. Although the vocalizations of the domestic dog are similar to its closest relative, the wolf, dogs vocalize in a wider variety of social contexts compared with wolves. For example, while barking seems to be common in young canids, selection for tameness may have led to the retention of this juvenile characteristic in the domestic dog even into adulthood with the result that the domestic dog relies more on barking as a communication tool than its wild counterparts (Bradshaw & Nott, 1995). In terms of its functionality when communicating with humans, studies have shown that humans can contextualize and therefore respond to a dog’s bark based on its frequency and modulation, (Yin & McCowan, 2004). It would therefore appear that the domestic dog has developed different and numerous vocal signals as a result of their functionality in conveying specific information to communicate with humans (Siniscalchi et al., 2018).
Similarly, the domestic cat is more vocal and uses vocalization in more contexts than its wild ancestors. The
vocalizations of wild felids are lower in frequency than that of domestic cats and are perceived as less pleasant
by humans. This suggests the possibility that humans may have selected for a more ‘pleasant’ cat voice.
Humans can also differentiate between positive and negative affect in their cat’s vocalizations and can respond
accordingly, making this an effective tool for interspecific communication (Houpt, 2011).
Visual signals tend to be a more immediate and persistent form of communication than either vocal or olfactory signaling. Visual signals travel at the speed of light and are therefore propagated almost instantaneously over a range of distances (Bolhuis & Giraldeau, 2005). They may also be persistent, as can be the case with the marks left by a cat on a favorite scratching site. In this case, the visual marker may also aid in olfactory communication as it draws attention to the scent deposited from the glands on the paws (Turner & Bateson, 2000).
While both the domestic dog and its closest relative, the gray wolf, have an
extensive range of social communicative behaviours (Abrantes, 2005), the
domestication of the dog has resulted in the development of unique visual
communication patterns that facilitate dog-human communication while at the
same time altering, and in some cases resulting in a loss of many of the visual
signaling structures of the dog (Overall, 1997).
Nevertheless, the postural and visual signals used by domestic dogs may still be
compared to a two-dimensional wolf model: aggressive/fearful and dominant/
submissive. For example, both wolves and dogs use a variety of visual signals such
as posturing of the ears, mouth, facial expression, hair, and overall position and
stance to convey distance increasing and distance decreasing messages. In the
context of agonistic encounters, an aggressive posture will be upright, with the
head and tail held high and the ears pricked. A dominant/aggressive canid will
also display piloerection, curled lips and bared teeth. A subordinate or friendly
posture will serve to decrease the signaler’s size relative to the receiver: the body
is held low, the ears are flattened, and the tail is low and close to the body. A
subordinate/fearful canid will further exaggerate this posture and may roll on its
back and present the inguinal region to the receiver (Bradshaw & Nott, 1995).
Dogs also regulate social distance and interaction through their facial expression, modifying gaze, ears, and mouth position. For example, the eye region plays an important informative role especially where sustained eye gaze is used. Dogs may use the stare to signal a threat; however they also use staring in play behaviour. In this regard, staring in dogs conveys different information depending on the animal’s posture and the context in which it is used (Bradshaw & Nott, 1995).
The use of the tail is another important part of a dog’s communicative behaviour patterns. A loose free-wagging tail conveys friendliness, a low, stiff-wagging tail is generally seen as an appeasement signal, a tucked tail is indicative of fear, and a stiff, upright-flagging tail conveys threat and possibly active aggression (Bradshaw & Nott, 1995).
Both undomesticated and domestic felids are generally solitary hunters, but both species enjoy a flexible social system. They tend to live in groups when food is plentiful but spend most of their time out of sight of one another. The signaling structures of the domestic cat have not been affected by domestication to the same extent as that of the domestic dog.
Similar to dogs, cats also use a variety of visual signals to communicate. The postures used by the domestic cat function in a similar way in agonistic encounters to those used by the domestic dog. An aggressive posture will be upright with piloerection and the cat may adopt a side-on stance, thereby effectively increasing in size relative to the receiver. The subordinate cat will crouch low to the ground, withdraw its head, and flatten its ears, effectively decreasing its size. In cats, rolling on the side or back is usually a male-male signal used to communicate submission, or as a component of female proestrus behaviour.
Cats also use facial expression to regulate social distance and interaction. In situations that involve
agonistic encounters between two cats, the cats will keep track of each other without locking gazes.
However, direct, fixed eye contact with constricted pupils is an offensive or stare threat that can be used to
regulate social and territorial distance. This is in contrast to a nervous or fearful cat who will have dilated
pupils (Turner & Bateson, 2000). Staring can also be used in play behaviour, particularly in kittens. In the
face-off play category, two kittens will look intently at each other while directing paw movements at each
other’s faces (Beaver, 2003).
The cat’s mobile tail has an independently movable tip and is used for signaling as well as to maintain
balance. A vertically held tail-up position indicates affiliative behaviour, aggressive behaviour is signaled
by a side to side lashing of the tail together with piloerection, and submissive/defensive behaviour is
signaled by a tucked tail. Undomesticated felids do not appear to use the tail as a signaler to the extent that domesticated cats do (Turner & Bateson, 2000).
Chemical signals are probably the most common signals used by animals. They rely on the speed of air or water currents and are therefore the slowest signals. However, chemical signals can persist: they can remain in the environment for days or weeks, functioning even when the sender is not present. This also allows for a time delay between the sending and the receiving of a signal and allows a receiver to come to the signal rather than the signal coming to them. On the other hand, scent can be dispersed by the elements and, because of its persistence in the environment, the signaler cannot control who the receiver may be (Bolhuis & Giraldeau, 2005).
Dogs have a very acute sense of smell: they have a large area of olfactory epithelium and a vomeronasal organ that functions in sexual behaviour. They use olfactory communication in two ways: via the deposition of faeces, urine, and anal sac secretions, and through their individual, distinctive body odors (i.e. glandular secretions). Unlike wolves that use faeces to communicate their residency, there is no evidence to suggest that domestic dogs use faeces alone for communication. Domestic dogs do investigate the faeces of other dogs and male dogs are more inclined to mark with faeces than female dogs. Anal gland secretions are eliminated with the faeces and may give them a unique odor. Dogs may use these sac secretions to identify one another, and they may also be expressed as a fear pheromone. Domestic dogs do use urine to mark territories and home ranges. They may overmark the urine of other dogs and may scratch the ground after urination to spread the scent. The most powerful form of olfactory communication is the urine of the estrous bitch. This urine contains pheromones that can attract male dogs from great distances. Male dogs flick their tongues just behind their incisor teeth, introducing estrous urine into the vomeronasal organ (Bradshaw & Nott, 1995).
Dogs have a variety of subaceous and sudoriferous glands that produce body odors. These glands are found
all over the body with particular concentrations around the head, the anal region, the upper surface of the
tail, and the perineum. Dogs will sniff these areas, particularly the anal and tail areas, of both familiar and
unfamiliar dogs, suggesting that they receive some information from the scents (Bradshaw, 1995).
For both domestic and undomesticated cats, olfactory communication is particularly important. Scent can be
used to avoid encounters with conspecifics, and to produce colony or group specific odors. Similar to canids, undomesticated cats use faeces more frequently than domestic cats to communicate residency and mark territories. Also similar to dogs, the cat’s anal gland secretions have a very distinctive odor and are secreted by a frightened animal. Cats deliberately scent mark with urine by spraying on vertical surfaces. Both males and females spray but males, particularly free-ranging tom cats, spray most frequently. Urine marks are intently investigated by other cats, first by sniffing and then by flehman. Flehman is similar to the dog’s behavior of moving the tongue just behind the incisor teeth, introducing air and fluid borne molecules into the vomeronasal organ. This behaviour gathers and perhaps stores social information about other cats (Turner & Bateson, 2000).
Like dogs, cats have a variety of skin glands, particularly on the paws, beneath the chin, at the corners of the
mouth, on either side of the forehead, at the base of and along the tail, and in the external ears. Cats may
deposit scents on different surfaces by scratching or rubbing against objects, and exchange scents by rubbing
against each other. Like dogs, cats will sniff one another to gather social information but, unlike dogs, will
concentrate on the head region (Turner & Bateson, 2000).
Abrantes, R. (2005). The Evolution of Social Canine Behavior. Michigan: Wakan Tanka Publishers.
Bolhuis, J. J. & Giraldeau, L. (2005). The Behavior of Animals. Mechanisms, Function, and Evolution. Oxford: Blackwell Publishing.
Bradshaw, J. W. S. & Nott, H. M. R. (1995). Social and communication behavior of companion dogs. In J. Serpell, The Domestic Dog (pp. 115-130). Cambridge: Cambridge University Press.
Beaver, B. V. (2003). Feline Behavior, A Guide for Veterinarians. Missouri: Saunders.
Houpt, K. A. (2011). Domestic Animal Behavior for Veterinarians and Behavior Scientists. Iowa: John Wiley & Sons, Inc.
Overall, K. L. (1997). Clinical Behavioral Medecine for Small Animals. Missouri: Mosby.
Turner, D. C. & Bateson, P. (2000). The Domestic Cat: The biology of its behavior. Cambridge: Cambridge University Press.
Yin, S. & McCowan, B. (2004). Barking in domestic dogs: context specificity and individual identification. Animal Behaviour 68 , 343-355.