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There are two
recognized species of wolves in the world: the gray wolf (Canis lupus) and the
red wolf (Canis rufus). The Ethiopian (or Abyssinian) wolf, (Canis simensis) is
questioned as a true wolf as some researchers believe the Ethiopian wolf is not
a wolf, but actually a jackal.
The gray wolf, Canis
lupus, lives in the northern latitudes around the world. There are five
subspecies of the gray wolf in North America and seven to 12 in Eurasia. The
currently recognized subspecies in North America are:
·
Canis lupus
baileyi,
commonly referred to as the Mexican wolf or lobo.
·
Canis lupus
nubilus,
referred to as the great plains, timber or buffalo wolf.
·
Canis lupus
occidentalis,
known as the northwest, Rocky Mountain or MacKenzie Valley wolf.
·
Canis lupus
lycaon,
commonly referred to as the eastern timber wolf.
·
Canis lupus
arctos,
known as the arctic wolf.
Subspecies are often
difficult to distinguish from one another. This is because they interbreed where
their ranges overlap so that their populations tend to blend together rather
than form distinctive boundaries. The different traits we see in subspecies are
likely the result of geographic range, available habitat, and prey base. Skull
dimensions, overall size, fur color, and the length of appendages are some of
the characteristics that differ between subspecies of gray wolf.
Wolves usually live
in packs which consist of the adult parents, referred to as the alpha pair, and
their offspring of perhaps the last 2 or 3 years. The adult parents are usually
unrelated and other unrelated wolves may sometimes join the pack.
Pack size is highly
variable because of birth of pups, dispersal, and mortality. Generally, a gray
wolf pack has from six to eight wolves, but in Alaska and northwestern Canada
some packs have over 30 members.
Red wolf packs are
generally smaller than gray wolf packs and usually have 2 to 8 members, but a
pack of 12 is known in the wild.
Territory size is
highly variable. Gray wolf territories in Minnesota range from about 25 to 150
square miles, while territories in Alaska and Canada can range from about 300 to
1,000 square miles.
Red wolf territories
can be from 10 to 100 square miles, but the territories of red wolves
reintroduced into North Carolina have been 38 to 87 square miles.
Wolves breed at
slightly different times, depending on where they live. For example, gray wolves
in the Great Lakes Region breed in February to March, while gray wolves in the
Arctic may breed slightly later in March to April.
Red wolves usually
breed in January or February.
The gestation period
of gray and red wolves is usually around 63 days.
A pack normally has
only one litter of pups each spring, but in areas of high prey abundance more
than one female will give birth in each pack. An average litter size for gray
and red wolves is 4 to 6, but several may die if natural prey is not readily
available.
Gray wolf pups weigh
1 pound at birth, while red wolf pups weigh less than a pound at birth.
Adult female gray
wolves in northern Minnesota weigh between 50 and 85 pounds, and adult males
between 70 and 110 pounds. Gray wolves are larger in the northwestern United
States, Canada, and Alaska where adult males weigh 85 to 115 pounds and
occasionally reach 130 pounds.
Adult female red
wolves weigh 40 to 75 pounds, while males weigh from 50 to 85 pounds.
The average length
(tip of nose to tip of tail) of an adult female gray wolf is 4.5 to 6 feet;
adult males average 5 to 6.5 feet. The average height (at the shoulder) of a
gray wolf is 26 to 32 inches.
The average length
(tip of nose to tip of tail) of an adult red wolf is 4.5 to 5.5 feet. The
average height (at the shoulder) of an adult red wolf is about 26 inches.
The size of a wolf's
track is dependent on the age and size of the wolf, as well as the substrate the
track was made in. A good size estimate for a gray wolf's track size is 4 1/2
inches long by 3 1/2 inches wide. In comparison, a coyote's track will be closer
to 2 1/2 inches long by 1 1/2 inches wide. Only a few breeds of dogs leave
tracks longer than 4 inches (Great Danes, St. Bernards, and some bloodhounds).
Adult gray and red
wolves have 42 teeth, while adult humans have 32.
The massive molars
and powerful jaws of a wolf are used to crush the bones of its prey. The biting
capacity of a wolf is 1,000 to 1,500 pounds of pressure per square inch. The
strength of a wolf's jaws makes it possible to bite through a moose femur in six
to eight bites. In comparison, a German shepherd has a biting pressure of 750
pounds per square inch. A human has a much lower biting pressure of 300 pounds
per square inch.
Gray wolves prey
primarily on large, hoofed mammals such as white-tailed deer, mule deer, moose,
elk, caribou, bison, Dall sheep, musk oxen, and mountain goat. Medium sized
mammals, such as beaver and snowshoe hare, can be an important secondary food
source. Occasional wolves will prey on birds or small mammals.
Red wolves primarily
prey on white-tailed deer, raccoons, rabbits and rodents.
Gray wolves can
survive on about 2 1/2 pounds of food per wolf per day, but they require about 5
pounds per wolf per day to reproduce successfully. The most a gray wolf can eat
in one sitting is about 22.5 pounds.
Red wolves eat an
average of 5 pounds of food per day, but have been known to eat up to 12 pounds
in one sitting.
In Minnesota, wolves
kill the average equivalent of 15 to 20 adult-sized deer per wolf per year.
Given the 2004 estimate of 3,020 wolves in Minnesota, that would equal about
45,300 to 60,400 deer killed by wolves. In comparison, from 1995-1999 hunters
killed between 32,300 to 78,200 deer each year in Minnesota's wolf range. In
addition, several thousand deer are killed during collisions with vehicles each
year.
Gray wolves in the
wild have an average life span of 6 to 8 years, but have been known to live up
to 13 years in the wild and 16 years in captivity. Red wolves in the wild have
an average life span of 8 to 9 years, but have been known to live up to 12 years
in the wild and 16 years in captivity.
The natural causes of
wolf mortality are primarily starvation, which kills mostly pups, and death from
other wolves because of territory fights. While not usually a big problem,
disease such as mange and canine parvovirus can be a concern in small and
recovering populations. Injuries caused by prey results in some deaths.
Human-caused mortality including legal, illegal, and accidental causes, can be
high in some populations. Pup mortality rates are highly variable, but
approximately 40 to 60% of wolf pups die each year.
Wolves will travel
for long distances by trotting at about five miles per hour. They can run at
speeds of 25 to 35 miles per hour for short bursts while chasing prey.
Wolves may travel 10
to 30 miles each day in search of food. Dispersing wolves, those leaving packs
in search of their own mate, have been known to travel distances of 550 miles
away form their home territory.
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