Grey Wolf Communication

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A pack of wild Yellowstone wolves socially interacting near a herd of wild Bison (Photo credit: S Jones)

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A pack of wolves hunting Elk in Yellowstone National Park (Photo credit: S Jones)

The above photos (taken and donated by a friend of mine!) show some wolves interacting; there appears to be some form of social gathering in the first photo, and the second photo shows wolves hunting together – so, there must be some form of communication taking place among these wolves, but what exactly? What and how do wolves communicate within a pack? And why? Well, hopefully the following info I have written will give you some insights into the intricate ways in which wolves exchange information with one another, and hopefully allow you to see just how complex and fascinating these animals truly are.

Grey wolf communication | Background

Grey wolves (Canis lupus) are intelligent, social animals, living in packs ranging in size from two, to up to 42 individuals1. In fact, wolves have the most highly developed social system of all canids2, and are frequently used as a model for describing the social behaviour of group-living animals3; there are some who even consider them to be quite primate-like in their social behaviour!!

Wolf packs are essentially family units, generally (but not always!) consisting of a monogamously mated pair (the parents of the pack), their current pups, and previous adolescent offspring that have not yet dispersed from the pack (dispersal would usually occur upon maturity at 22 months old2,4,3,5). The parents are often referred to as the ‘alpha’ pair, followed in ranks by a ‘beta’ wolf, and at the bottom of the pack, the lower rank, being the ‘omega’ wolf, with auxiliaries of varying ranks in between. There are generally two separate social rank orders within wolf packs, one for females, and one for males6,3,5,2. However, the terms alpha, beta and omega are archaic and stem from behavioural observations conducted on non-stable captive wolf packs3; whereby unfamiliar wolves from different packs were amalgamated by humans, thus the natural social rank orders that occur within stable packs, formed and maintained by the family unit, were broken. The broken order of these human produced ‘packs’ resulted in frequent bouts of active dominance, often leading to conflict (forced-based dominance) as each wolf would try to establish its own rank within the new pack. Researchers at the time were lead to believe that wolf packs were governed by these frequent agonistic behaviours, and hence the afore-mentioned archaic terms were coined! But, wild wolves are rarely seen to engage in dominance contests3, nor are any other stable packs, wild or captive (such as my research wolves at the UK Wolf Conservation Trust). The term alpha can only really be applied to large packs3 with many auxiliaries; agonistic behaviour would be more likely to occur among adolescent auxiliaries as they attempt to establish dominance hierarchies, whereas with adults, dominance hierarchies have already been established and thus, pack cohesion and stability created. Through many vigorous behavioural observations of stable packs, we now know that wolves are not governed by heinous active dominance, they are in fact, directed simply by cooperation brought about by communication, particularly intra-pack (within-pack) communication, which is my area of research!!

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Black Yellowstone wolf (Photo credit: S Jones)

Grey wolf communication | The basics

Communication within wolf packs is vital to reduce aggression among pack members, thus maintaining pack cohesion and stability5. Wolves have a vast repertoire of communicative behaviour, utilising olfactory, auditory and visual modalities of communication7, to convey information about their ‘affective states’ and social status to other pack members5. Now this term, affective states, what are they? They are forms of motivation such as emotions, moods, attitudes, desires, preferences, intentions and dislikes8. What’s the point of understanding the affective states of non-human animals? Well, first and foremost, animal welfare; being able to discern an animal’s ‘emotional’ state is key to maintaining its health and psychological well-being9,10; highly important to understand for non-invasive methods of assessing the psychological and potentially physiological states of animals, i.e studying stress (an affective state, brought about by either intrinsic or extrinsic factors effecting the individual animal in question) in both captive and wild animals.

Grey wolf communication | Olfactory mode

Olfactory communication in wolves generally consists of scent marking via urination, defecation and scratching of the ground, usually along territorial boundaries in conspicuous places11,12,13,14,15. It should be noted that higher ranking wolves (male and female) generally perform ‘raised-leg urinations’, while subordinate individuals (male and female) will squat when urinating. The above methods of olfactory communication are widely considered as inter-pack (between-pack) communication for territorial purposes. But, as previously mentioned, my area of research lies with intra-pack communication, in that I research the communication that forms and maintains social bonds between individuals within a pack. Intra-pack olfactory communication in wolves involves investigatory behaviour of the head, neck and anal-genital area of pack conspecifics5, for example, ‘snuffling’ behaviour as described by Schenkel16. Anyone who shares their life with a domestic dog may also be very familiar with the way two dogs ‘greet’ each other, by sniffing each other’s ‘behinds’, much like the interaction depicted in figure 1; this interaction shows two wolves inspecting the anal regions of one another. The anal region of a wolf has five possible sources of scent, which can be detected by another wolf upon inspection; these include genital glands, anal- sac secretions, the precaudal gland, and traces of urine and faeces5. It is not known what information is transferred via anal region inspections5, but Eisenberg and Kleiman17 describe the possible information that may be conveyed through different sources of scent in canids and other taxa, so I highly recommend you have a quick read through their work!

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Figure 1. Two wolves inspecting the anal regions of one another, the dominant wolf performs ‘anal presentation’ by raising its tail, while a low ranking subordinate performs ‘anal withdrawal’, by lowering its tail. Adapted from Schenkel16.

Grey wolf communication | Auditory mode

Wolves are renowned for howling, nature’s greatest song, sung out across the wilderness, travelling up to six miles (in ideal conditions1), away from the signalling wolf to the ears of a receiving wolf, or anyone who has the pleasure to hear it. As well as a vocalisation that can haunt the imaginations of many and resonate through your soul, howling has been of great interest to wolf researchers for decades; varying theories for the function of wolf howls include inter-pack territorial behaviour, to rally separated pack members after a hunt, to maintain strong family bonds, attracting a mate, and some researchers even theorise that wolves will simply howl just for fun!1,4. What’s more fascinating is that wolves seldom howl on the same note continuously; individual wolves howling in chorus will change the frequency and pitch of their howls (thus increasing variability) to make it sound as if their pack contains more members than it actually does!1,4.

Adult wolves produce a wealth of other vocals also, including growls and snarls, and plaintive yips and yaps, and combinations such as growl-barks4,18,19, however, these sounds are subdivided into four main vocalisations; the growl, whimper, bark, and previously discussed howl19. A fifth vocal also exists, the ‘social squeak’, but relatively little is known about this vocalisation5. The complexity of each vocalisation is depicted in their frequency ranges and durations (figure 2). Harrington and Mech19 discussed each wolf vocalisation in detail (again I recommend a read!), and it has been shown that these vocals are utilised in various intra-pack interactions to convey information of affective states to pack conspecifics.

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Figure 2. Adult wolf vocalisation sonograms; showing the ranges of frequencies and durations of the whimper, growl, bark and howl of adult individuals. Adapted from Harrington and Mech19.

Grey wolf communication | Visual mode

The main mode of intra-pack communication in wolves is visual, which involves the utilisation of the entire body5, including tail shape and positioning16,20, and postural displays16,20. But, the most visually expressive part of a wolfs’ body is its head16,20, with a wealth of facial expressions21,16, but more on that in a moment!

Visual mode | Postural displays

Postural displays are utilised to mostly convey social status in wolves and are many and varied, and context specific5. In most social interactions of postural displays, dominant wolves appear ‘self-inflated’, giving the impression of ‘explosive readiness’ to attack5,16, while subordinates appear ‘self-deflated’, either giving the impression of ‘friendliness’ during active submission or the impression of timidity during passive submission5,16 (similar to figure 3). But remember, in stable packs these interactions are seldom seen!

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Figure 3. The domination-submission ritual; the dominant wolf appears ‘self-inflated’ and grasps the muzzle of the subordinated (who appears ‘self-deflated’) forcing it to the ground, an act of active assertion/dominance. Adapted from Schenkel20.

Visual mode | Tail positions

The position, shape and movement of a wolf’s tail conveys information about either status or affective states during social interactions16. For example, a loose, freely hanging tail wagging with large amplitudes signifies a ‘friendly’ state, while more submissive individuals have a more elaborate swinging of the entire hind-quarters accompanied by a pulled-in tail5,16. Aggressive states are often depicted by raised tails, accompanied by sudden, rapid wagging of the entire tail or just the tail tip5,16. See figure 4 for some examples of tails positions and shape.

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Figure 4. Various tail positions seen in wolves; a portrays ‘self-confidence’ during social interactions; b is an indication of certain threat towards a conspecific; c portrays an ‘imposing attitude’, often seen with sideways brushing of the tail; d is a relaxed state; e is an uncertain threat towards a conspecific; f is another variation of a relaxed state; g indicates depression (note the lowered base of the tail and contrast with d & f); h is in between threat and defence; i and j are characteristic of ‘self-deflation’; k is a character of increased submission. Adapted from Schenkel16.

Visual mode | Facial expressions

(Finally, the main focus of my research – wolf facial expressions!)

As previously stated, the most visually expressive part of a wolfs’ body is its head16,20; combinations of facial features, including pelage patterning (colouration and fur slope), mimic muscle movements, and the activities of the eyes, nose and ears, emphasise the appearance of the snout, lips, eyes, forehead and ears (the main conveyors of facial expressiveness22,21,16). Past studies show that wolf facial expressions convey affective states and social status21,16 (figure 5); however, these studies are dated and lack quantitative data, they only cover agonistic behavioural interactions, and they do not consider the individual behaviour of the wolves being studied. So, this is where I come in, to fill the gaps and update this area of research! While also researching the effects of facial morphology divergence (from an ancestral wolf form) in domestic dogs (Canis lupus familiaris) on their ability to effectively communicate in a pack environment – are their facial expressions similar or different to that of wolves? So, to learn more about the facial expressions of wolves and their domestic cousins keep an eye on this space!!

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Figure 5. Various facial expressions seen in wolves, conveying social status and affective states; a and b show the relaxed facial expressions of a dominant, high ranking wolf; c and d show the facial expressions of an anxious wolf; e and f are the facial expressions of a threatening wolf; g and h portray suspicion or doubt. Adapted from Schenkel16.

References:

  1. Mech LD & Boitani L (2003). Wolves, Behaviour, Ecology, and Conservation. United States of America: The University of Chicago Press.
  2. Sheldon JW (1992). Wild dogs: The natural history of the nondomestic Canidae. United States of America: Academic Press Limited.
  3. Mech LD (1999). Alpha status, dominance, and division of labor in wolf packs. Canadian journal of zoology, 77: 1196-1203.
  4. Busch RH (2007). The wolf almanac: A celebration of wolves and their world. 3rd China: The Lyons press.
  5. Mech LD (2007). The wolf: The ecology and behaviour of an endangered species. 13th United States of America: University of Minnesota press.
  6. Mech LD (1974). Canis lupus. Mammalian species, 37: 1-6.
  7. Fox MW (1975). Ch. 30: Evolution of social behaviour in canids. In The wild canids: Their systematics, behavioural ecology and evolution. Ed. Fox MW, 1975, pp. 429-460. New York: Van Nostrand Reinhold.
  8. Sloman A, Chrisley R & Scheutz Matthias (2003). The architectural basis of affective states and processes. For inclusion in Who needs emotions?: The brain meets the machine. Ed. Fellous and Arbib, United Kingdom: Oxford University Press.
  9. Desire L, Boissy A & Veissier I (2002). Emotions in farm animals: a new approach to animal welfare in applied ethology.Behavioural processes, 60: 165-180.
  10. Yeates JW & Main DCJ (2008). Assessment of positive welfare: a review. The Veterinary Journal, 175: 293-300.
  11. Barja I, de Miguel FJ and Barcena F(2004). The importance of crossroads in faecal marking behaviour of the wolves (Canis lupus). Naturwissenschaften, 91: 489-492.
  12. Peters RP and Mech LD (1975). Scent-Marking in Wolves: Radio-tracking of wolf packs has provided definite evidence that olfactory sign is used for territory maintenance and may serve for other forms of communication within the pack as well. American Scientist, 63: 628-637.
  13. Rothman RJ and Mech LD (1979). Scent-marking in lone wolves and newly formed pairs. Animal behaviour, 27: 750-760.
  14. Briscoe BK, Lewis MA and Parrish SE (2002). Home range formation in wolves due to scent marking. Bulletin of Mathematical Biology, 64: 261–284.
  15. Petak I (2010). Patterns of carnivores’ communication and potential significance for domestic dogs. Periodicum Biologorum, 112: 127-132.
  16. Schenkel R (1947). Expression-studies of wolves. Behaviour, 1: 81-129.
  17. Eisenberg JF and Kleiman DG (1972). Olfactory Communication in Mammals. Annual Review of Ecology and Systematics, 3: 1-32.
  18. Feddersen-Petersen DU (2000). Vocalization of European wolves (Canis lupus lupus L.) and various dog breeds (Canis lupus f. fam.). Archiv fur Tierzucht, 43: 387-398.
  19. Harrington FH and Mech LD (1978). Wolf vocalisations. In Wolf and man evolution in parallel. Ed. Hall R and Sharp H, 1978, pp. 109-132. United States of America: Academic press.
  20. Schenkel R (1967). Submission: Its Features and Function in the Wolf and Dog. American Zoologist, 7: 319-329.
  21. Fox MW (1970). A Comparative Study of the Development of Facial Expressions in Canids; Wolf, Coyote and Foxes. Behaviour, 36: 49-73.
  22. Bolwig N (1964). Facial Expression in Primates with Remarks on a Parallel Development in Certain Carnivores (A Preliminary Report on Work in Progress). Behaviour, 22: 167-192.
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Yellowstone wolf wearing a radio collar – technically a form of wolf to human communication! As researchers gather information about the individual wolf’s movements…..(Photo credit: S Jones)

 

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