BLACK WOLF: CHARACTERISTICS, HABITAT, FEEDING, REPRODUCTION - BIOLOGY - 2025

The black wolf is a phenotypic variety of gray wolf (Canis lupus) that has melanism on its fur. This variety of black fur can be found in various subspecies of wolves, such as the Italian and Asian wolves.

Originally this phenotypic variant was considered as a different species of the gray wolf, which is why the name of Canis lycaon was coined in the 18th century. However, various morphometric and genetic analyzes made it possible to include this melanistic variety within the Canis lupus species.

Wild Black Wolf in Yellowstone By Morehouse Keith, US Fish and Wildlife Service

The record of black wolves within the populations of the Asian gray wolf Canis lupus pallipes and the Italian gray wolf Canis lupus italicus has revealed that the black fur variant can be originated both by hybridization of wolves with domestic dogs, as well as independent recurrence of a mutation in these wolf populations.

These investigations highlight that the presence of feral or stray dogs is very rare in these areas, and hybridization events are highly unlikely for these wolf populations.

Melanism has been reported in other canid species such as the coyote (Canis latrans) and the eastern United States red wolf (Canis rufus).

General characteristics

Black wolves have very similar characteristics to gray wolves. Wolves in general can weigh between 30 and 60 kilograms, but black specimens have been found in southern Ontario that weigh between 7 and 10 kilograms more. They can measure between 1.5 and 2 meters in length from snout to tail.

Its tail measures between 35 and 40 centimeters and its skull is between 25 and 30 centimeters long and 12 to 15 centimeters wide. Its coat is moderately dense and thick.

The morphological variations of wolves are due to the hybridization of Canis lupus with other species such as coyotes (Canis latrans) or with domestic dogs (Canis lupus familiaris). The mutation that causes melanism is due to the elimination of three nucleotides. The latter has been detected in dogs, coyotes and wolves.

Probably the appearance of black wolves is due to the combination of dominant alleles. This genotypic combination occurs in black dogs and is rare, so only hybrid wolf-black dog combinations could produce a black wolf.

Origin of black fur

Mutations in the genes responsible for coat color, or hybridization with other species such as the coyote (Canis latrans) or with feral dogs, may be some of the causes of the morphological variables in Canis lupus.

Melanism in domestic dogs is controlled by the CBD103 gene, which is also related to the encoding of the protein beta-defensin.

This mutation is a deletion of three nucleotides at the K loci and has been detected in more than 50 breeds of domestic dogs and is also widespread in populations of wolves and coyotes in the western United States.

Molecular analyzes have shown that this elimination of nucleotides that cause melanism in wolves is the product of the migration of genes between two species (wolf x dog, coyote x dog, wolf x coyote) and the subsequent backcrossing of individuals.

In some wolf populations, such as Italian gray wolves, no hybridizations have been recorded in recent decades.

However, there is the occurrence of the black fur phenotype, which could give evidence of hybridization with feral dogs in the past, or spontaneous events of mutations related to the effects of various ecological factors and adaptation to environmental conditions.

Taxonomy

The Canis lupus species belongs to the Canidae family and has around nine subspecies, within which the phenotypic variation of the black wolf can appear.

In North America, there are five recognized subspecies, of which C. l. arctos and C. l. occidentalis show melanism. In Asia, at least two subspecies are recognized, being C. l. pallipes the most widespread in that continent, also presenting the black fur variant in some populations of Iran.

Of two subspecies described for Europe, melanism has only been reported for some populations of wolves of the subspecies C. l. italicus present in Italy.

Initially this phenotypic variety was described as a different species to the gray wolf (Canis lycaon). However, in the first decade of the 21st century, several genetic studies revealed that the black wolf exhibits the same mutation that domestic dogs with black fur present.

The domestic dog is classified by some zoologists as a subspecies of the wolf (Canis lupus familiaris) although it is also considered a different species (Canis familiaris).

Black wolf and white wolf specimens in zoo in France By Stéfan

Habitat and distribution

The black wolf is found in North America and some parts of Eurasia. In North America it is located in the western United States, Canada and Alaska. In Europe, it has been reported in Italy and Russia, currently only a few populations remain in eastern Italy.

In North America, black wolves have been recorded since the 16th century, tending to increase their occurrence in some regions. Currently its presence is common in the Great Lakes region, which includes Ontario in Canada, as well as eight states in the United States.

In addition, they are found in Minnesota and Yellowstone National Park, representing a significant percentage of wolf populations in these locations. In Europe, individuals of black wolves can be found in Italy in the Apennines and in the province of Arezzo.

In Asia, black wolves have been recorded in populations living in the Bahar region in Hamadan providence and in Ghidar in Zanjan providence, western Iran.

Like their gray-furred relatives, black wolves typically inhabit a wide variety of environments ranging from forests, rocky areas, scrublands, grasslands, wetlands, and deserts. However, its occurrence is more frequent in wooded areas.

State of conservation

The Canis lupus species is classified in the category of least concern (LC) according to the IUCN. Although the conservation status of the black wolf variety has not been evaluated and it is not very common in most localities where the gray wolf inhabits, it has a great representation within some wolf populations.

In the mid-20th century, black wolves accounted for more than 40% of the populations of Yellowstone National Park in the United States, and about 32% of wolf sightings in Canada concerned black-furred wolves.

In other locations such as Alaska, they represent more than 30% of the wolf population. In Italy, individuals of black wolves have been reported in resident populations of the Apennine mountain, representing between 23% and 30% of the population.

It is estimated that the number of individuals with the phenotype for black fur is currently increasing, because said coloration does not represent a disadvantage in sexual selection. In addition, the genotype for black color is related to resistance to certain diseases.

On the other hand, the less aggressive behavior of these individuals gives them a certain vulnerability to humans, who hunt them to market their skin or to consider them a threat.

Control and reintroduction of the wolf in the United States

During the 1920s and 1930s, wolf population control was carried out in Yellowstone National Park, driven by the damage caused by these animals to livestock. In addition to this, poaching and sport hunting of these animals reduced the populations of this species in its original range of distribution.

By the 1980s, Canis lupus was in danger of extinction, listed by the IUCN as "vulnerable" (V). All this despite the fact that, since the 1970s, several reintroduction programs were carried out in different locations in North America, in addition to reforestation and habitat recovery activities. The reintroduction of Canis lupus comprised both gray wolves and black wolves.

In the late 1990s, wolf populations became stable in some localities in the United States such as Minnesota, Wisconsin, Idaho, Arizona, and Oregon. However, the wolf's distribution has declined considerably due to the destruction of its habitat.

Feeding

Black Wolf By Matthias

Black wolves, like gray wolves, are flexible and opportunistic predators. They feed on a variety of hoofed animals that represent around 90% of their diets in some localities, as well as small and medium mammals such as rodents and even some aquatic animals such as seals and salmon.

One of their most common prey is the red deer (Cervus elaphus) on which they feed throughout the year. Wolf packs of 4-16 members have been recorded, following packs of ungulates during their migration times in Yellowstone National Park.

Generally, wolf packs wait in secret for their prey to be distracted to attack together, whether it is large prey such as antelope, horses, elk or bison.

Once the prey is surrounded, they attack by biting the back of the animal, causing deep wounds in the perineum area, which cause exsanguination in the animal.

In some cases, they kill their prey by biting the region of the trachea, when crossing the jugular. It is common for wolves to supplement their diet with some plant species and fruits, although predation by other mammals accounts for more than 80% of their diet.

Reproduction

Black Wolf Pup (Canis lupus) By English: NPS Photo

Wolves compose packs with a complex hierarchical order. In wolf packs, alpha individuals (male and female) make up the breeding pair. During the year, the breeding pair mates once between the months of January and April.

Both females and males reach sexual maturity at approximately six months of age. Once the female is in heat, she increases her aggressive behavior towards the other females in the herd, to inhibit the heat in them.

Intercourse occurs around 15 days after the onset of heat and can last between 10 and 30 minutes. The erectile tissue of the male penis expands while the muscles of the vagina contract stimulating ejaculation.

During this period, the male and female are united, placing their heads in opposite directions to be alert to any danger or threat.

Gestation lasts about 90 days and females can have between 12 and 18 cubs at each birth. The new litter usually migrate from the flock upon reaching sexual maturity, to found or join new flocks.

Negative selective pairing

In Canis lupus there is no selective pairing (known as negative selective pairing), that is, wolves do not choose their partners based on their similarities in coat color and other characteristics, but rather they usually choose a partner that differs of them phenotypically.

Some research has found that between 1995 and 2015, approximately 64% of wolf pairings in Yellowstone National Park were between a gray and a black individual. In this study, the proportion of black males with gray females and black females with gray males was very similar.

The allele for the black coloration (allele K) is a dominant character, since it has been possible to register that in the crosses of gray and black wolves, of an average of 14 pups per crossing, 10 generally result with black fur.

The low selectivity in the mating of these animals and the dominant character of the allele have allowed the permanence of the black fur phenotype in Canis lupus.

Biological efficacy

Some studies have shown that heterozygous black wolf individuals have higher biological (fitness) efficacy than homozygous black wolves. This means that your genes will spread more successfully to subsequent generations.

The high fitness of these heterozygous individuals may be due to the fact that the mutation for black fur is associated with high levels of the protein beta-defensin. This protein is related to immunity to viral and bacterial infections in the skin.

On the other hand, homozygous black wolf females are rare and have 25% fewer live offspring than gray females.

Because of this, female gray wolf have greater reproductive success. It is possible that the immune advantage of individuals with black fur has a reproductive cost, causing a balanced selection of this phenotype.

References

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