This is a visual comparison of the Mackenzie Valley Wolf/Canadian Timber Wolf (occidentalis) and the now very-likely-extinct Northern Rocky Mountain Wolf (irremotus). Occidentalis is the subspecies that was illegally transplanted into the United States and ultimately caused the extinction of irremotus, most likely through interbreeding. Below is a brief summary of physical and behavioral differences between the two subspecies.


Canis lupus irremotus:

• Body size: Females ~55-70lbs.; Males ~85-105lbs.
• Highly secretive behavior; very sensitive to roads and highways; largely nocturnal
• Usually found either as dispersed individuals or pairs
• Packing activity was very rare except during the months of January-February
• Pack size at breeding time was usually 4-7 individuals
• Females retained pups for an average of 18 months
• Pack dispersal was very consistent after breeding season
• Litter size consistently around 1-3 pups; females bred at 2 years old
• Extremely selective regarding food source; rarely fed on old carcasses or kills of other species, except in the most harsh winter conditions
• Very much an opportunist when different prey was available; spent great percentage of hunting effort on rodent acquisition
• Surplus killing almost negligible; most ungulate depredation was consumption; typical kill showed hams and shoulders consumed
• Territory of individuals or pairs was quite large; average 2 week return cycle
• Competition with other predator species including coyote and fox was low; other canine species coexisted and thrived in presence of resident wolves
• Habitat utilized consistently: mid to high elevation, with forest and mixed taiga; resident wolves were very resistive to utilizing large areas of open rangeland with grass or sagebrush cover
• Older mature males almost always solitary
• Conflict with domestic dogs very minimal except in rare cases
• Livestock depredations extremely rare but do occur in remote areas
• Consistent avoidance of man-made structures, roads, vehicles, and humans
  

Canis lupus occidentalis, 1996 to present:

• Body size: Females ~60-85 lbs.; Males ~90-120 lbs.
• Exhibits low level of fear of humans; non-secretive behavior; minimal avoidance of humans, vehicles, domestic animals; will cross large open terrain at will even when other options for cover are available
• Mackenzie Valley wolf is found in small to very large pack sizes; small packs of 5 individuals are common up to large packs with over 20 members (eg., Hog Valley wolf pack containing 40 members)
• Pack merging, which is the condition of two or more packs combining, is being observed in many areas in the west and is not uncommon; merged packs which result in 40 wolves have been observed in the central Idaho wilderness
• Females can be bred even at one year of age, and produce from 5-9 pups per season; pups usually remain with the pack but can disperse or be driven off by other pack members
• All females of breeding potential in the pack are usually bred; there is absolutely no indication that any females are kept from breeding by the lead female; large packs are quickly produced and can disperse and merge several times within a week
• Mackenzie Valley wolves show a diet preference for elk calves but will switch at will to a secondary prey species; low preference is shown for rodent species, but wolves do sporadically hunt rodents
• Surplus killing is highly developed in Mackenzie Valley wolf packs; from observations in the field, 3-5 ungulates are killed for each ungulate consumed; this killing is greatly increased if the pack size is large or packs have merged; often small wintering herds of deer or elk as well as livestock are completely extirpated in one hunting event.
• Competition with other predatory species is extreme and often fatal; both mountain lion and bear have been impacted by attacks and from reduced available prey; other canines such as coyotes and fox have been severely impacted in most of their habitats; foxes are only able to survive in habitats that include lots of willow or dense underbrush; coyote populations have been reduced by are persisting at lower than historic levels
• Mackenzie Valley wolves have been found to utilize all available habitats, from high elevation alpine to sagebrush deserts; this has allowed this variety of wolf to be opportunistic in all ecosystems available to it
• Large mature male wolves remain with the pack throughout the year, sometimes dispersing for short periods of time
• The Mackenzie Valley wolf is highly predatory on all domestic canines; hunting hounds are especially vulnerable to attacks and are usually killed outright in a confrontation by wolves
• Mackenzie Valley wolves have shown a preference for predating on domestic livestock even with abundant natural prey present; beef calves are the most common victims of wolf depredation
• Mackenzie Valley wolves show a high level of habituation to humans, and man-made structures; it is not uncommon to find Mackenzie Valley wolves in very remote areas eating out of dog dishes and coming onto porches of homes when the owners are present

Further information

• Skull size comparison, irremotus on left, occidentalis on right

---