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The Grey Wolf (Canis lupus)

The grey wolf, Canis lupus, is the most widespread of carnivores and the most misunderstood. Historically, the wolf occupied all habitats in the Northern Hemisphere that contained large ungulates, ranging from 20°N latitude to the polar ice pack, inhabiting dense forest to open grasslands, Arctic tundra to extreme deserts. However, as a result of human persecution and habitat destruction, their range has been reduced by approximately one third. They are now only found in a few areas of the contiguous United States, Canada, Alaska, Eurasia and a small population in Mexico. Europe has seen huge declines in wolf populations into the late 1960’s, shrinking the range and creating small isolated populations. However, a ban on poisoning and legal protection is all that was needed in most cases to aid recovery of populations; this is due in part to the wolves’ tenacity and ability to survive in the most degraded of habitats. However, although all European nations have subscribed to the Bern Convention (providing full legal protection of both wolf populations and their habitat) not all countries obey their obligations and still allow hunting of wolves. Romania remains the European stronghold for the wolf with figures ranging from 3000-4000 individuals (40% of the European population outside Russia), the majority of which reside in the Carpathian Mountain range.

Physical characteristics

The wolf is the second largest carnivore in Europe with males weighing up to 80kg and females rarely reaching more than 50kg and measuring 1-1.5m from the tip of the nose to the tip of the tail and can live for 6-10 years in the wild. They are also highly territorial with ranges on average of 200km2, with a core of around 35km2 in which they will spend 50% of their time. The fur colouration varies greatly from white through grey to grey-brown and black with each population usually being a blended mix of colours although it is not uncommon for an individual or entire population to be one colour. When pups are born they have darker fur and bright blue irises which change to yellow-gold between 2 and 4 months. Wolves are highly sociable living in packs of 2 to upwards of 30 individuals although packs in the Carpathians are small consisting of the dominant breeding pair (alpha male and female) their pups and a few juveniles. Each pack has a strong hierarchy where only the alpha male and female breed monogamously and although sexually mature adults are able to breed, breeding is usually prevented by the dominant pair whilst still in their natal pack to prevent inbreeding. In a thriving population where food is abundant, the alpha pair while breed every year producing a litter of 5-6 pups in spring to coincide with the birth pulse in herbivore populations. After a gestation period of 61-64 days, the pups are born blind, deaf and completely dependant on their mother. The pups then undergo four developmental stages to maturity:

1) neonatal period – birth to eye opening around 12-14 days
2) transition period – eye opening to around 20 days
3) socialisation period – 20-77 days
4) juvenile period – 77 days to maturity around 1-3 years

During these stages, the pups not only develop physically, but many of their reflex behaviours develop into interactive routines. The rapid learning during the transition and socialisation periods has important implications for the social context of learning later in life, for example vocalisations become differentiated and associated with specific contexts. Via trial and error pups are able to learn the consequences of their actions and with experience older pups develop counter-tactics. The ability to learn these counter-tactics during play may provide a basis of learning complex social relations later in life, as well as aerobic conditioning and practising of instincts useful for hunting. Upon reaching maturity (1-3 years), wolves will leave their natal pack to search for or form their own pack rather than challenging for dominance, this is the only time a stranger will be accepted into another pack.

Communication

Communication between wolves occurs through a variety of signals including vocal, olfactory, tactile, gustatory and visual. Signals can be defined as the behaviours and features of animals that have evolved to encode the information being conveyed.

Vocal communication is the most familiar and development has been recorded in the den from as early as birth to 6 weeks with all adult sounds recognised by 3 weeks of age. Harmonic sounds such as whimpering, whining and yelping are associated with friendly or submissive contexts, while noisy sounds such as growls, snarls, woofs and barks are associated with aggression, including assertion of dominance. Howling, possible the most characteristic sound of wolves, occurring at 150-780Hz, is used for a wide variety of reasons including keeping the pack in touch with each other and calling the pack together at a specific location.

The olfactory sense is probably the most acute of the wolf’s senses, with scent marking providing information for day’s even weeks on gender, breeding condition, social status, condition and even diet. These olfactory signals are honest and most are produced by physiological and bacteriological processes, and it has been shown that subordinate male wolves excrete elevated levels of corticosteroids in the urine when under social stress. Communication generally occurs between pack members and is commonly used to affirm the dominance hierarchy through a combination of signals; this aids the quick settling of conflicts within packs through visual and vocal signalling of dominance and submission. Scent marking and howling are often used to affirm territory boundaries of neighbouring packs, indicating the location of the core of the territory and enforcing a territory-independent buffer zone.

Predator-prey & predator-livestock relationships

Although grey wolves are flexible and opportunistic predators, their main food source tends to be medium to large ungulates, but they will take small mammals, ground-dwelling birds, insects and carrion and will also rob other predators of their prey. In the wild, wolves play an important role in the regulation of wild ungulate populations, preying on the old, sick and young. There are recorded incidences of livestock being taken but these have mainly occurred in areas where there is insufficient ungulate prey. In Romania, depredations on livestock have declined since the populations of native ungulates were restored and animal husbandry techniques improved.

Wolves predominantly prey on the less fit individuals of a population, this does mean that hunts can often be unsuccessful and they must endure a feast or famine existence. Wolves have become well adapted to this feast-or-famine lifestyle they lead in a number of ways. Once a wolf is sated, it begins to cache excess food, these caches may contain anything from intact carcasses to regurgitated food and this behaviour appears to occur predominantly in summer when they hunt in small packs or individually and helps them through times when prey are less abundant. Another adaptation to food scarcity is the ability to locate suitable prey over large areas, even when it is scarce or less vulnerable. The exceptional senses of the wolf greatly aid them in prey searches along with the ability to assess the vulnerability of the prey in a given situation, and therefore the decision as to abandon or press the attack, are continually honed with each hunt. Honing of these skills may lead to prey specialisation in some wolf populations.

What now?

As human populations continue to grow, suitable available land for wolves to roam and colonize will decrease, and resulting habitat destruction remains the greatest long-term threat. Wolf management is a complex and controversial area consisting of four main problems. The first is defined as the clash between the wolf’s biology and human legal structure that has been overcome by the wolf’s enormous flexibility and buffering in its natural history. Secondly, conservation is a multidisciplinary process and as such requires teams that include biologists, sociologists, economists, land planners and such like. The third arises from political decisions made more on emotions than fact due to the complexity of wolf biology and ecology that has lead to simplifying matters to black and white. The final problem and probably the biggest to overcome is that of prejudice and ignorance which is widespread. To protect and conserve the grey wolf these problems must be addressed along with full understanding of the behaviour, ecology and adaptability of the species as well as tolerance, livestock protection techniques and acceptance.

References

Bekoff, M. 1984. Social play behaviour. Bioscience 34: 228-233.

Kreeger, T.J., DelGiudice, G. & Mech, L.D. 1997. Effects of fasting and feeding on body composition of gray wolves (Canis lupus). Canadian Journal of Zoology 75:1549-1552.

McLeod, P.J. & Fentress, J.C. 1997. Developmental changes in the sequential behaviour of interacting timber wolf pups. Behavioural Processes 39: 127-136.

Mech, L.D. 1970. The wolf: The ecology and behaviour of an endangered species. Natural History Press, Garden City, N.Y

Sax, J.L. 1991. Ecosystems and property rights in Greater Yellowstone: The legal system in transition. Pp 77-84 in R.B. Keiter & M.S. Boyce, eds., The Greater Yellowstone ecosystem: Redefining America’s wilderness heritage. Yale University Press, New Haven, CT.

Scott, J.P. 1967. The evolution of social behaviour in dogs and wolves. American Zoologist 7:373-381

Wolves: Behaviour, Ecology and Conservation. 2006. Edited by Mech, L.D. & Boitani, L.