MAC COMO ZOO

 

Gray Wolf

gray wolf pic
Scientific Name:
Canis lupus

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Order:Carnivora

Family:Canidae

Distribution: Originally, Gray Wolves had the largest distribution of any mammal except humans.  Their geographic range was mainly in the Northern hemisphere spanning from the Arctic towards South America and Southern Asia.  Today due to habitat destruction and environmental changes, the Gray Wolf is found only in the United States, Alaska, Canada, Mexico, and Eurasia. Unfortunately, by the mid-1930s, the killing of wolves greatly reduced the Gray Wolf population in the United States to parts of Alaska, Idaho, Michigan, Minnesota, Montana, Wisconsin and Wyoming. Today, Minnesota has the largest wolf population of any U.S state!

Habitat: Wolves are highly adaptable to most habitat types except tropical rainforests and arid deserts.  Wolves can be found in savannas, taiga, tundra, plains, steppes, and all forest habitats

Description: Adult male wolves average 95-100 pounds, while adult females average 80-85 pounds.  The heaviest wolf ever reported was 175 pounds, found in east central Alaska.  Male body length averages from 5- 6 ½ feet (from nose to tail tip), and females average from 4 ½- 6 feet.  Most wolves have a height of between 26 and 32 inches.  The wolf’s fur color also varies geographically, from white with gray, brown, black, cream-color, tawny, and some nearly all uniform black or white (in arctic conditions).  However the gray fur color tends to dominate, as is evidence by the name, the Gray Wolf.

Diet: Wolves are carnivores and they hunt individually, in packs, or by stealing the prey of other predators.  They are also known to scavenge on carrion.  They eat mostly ungulates (large hoofed mammals) like elk, deer, caribou and moose, and their diet depends on the availability and vulnerability of this prey in their area.  They also eat beavers, rabbits and other smaller mammals.  Lone wolves will usually hunt smaller animals, and packs will take down larger prey. Scavenging supplements their diet, especially during denning and pack activities.  Wolves will make full use of the carcass, including hair and bones, and can eat up to 19.8 pounds of meat in one feeding.  On a zoo diet, the wolves are fed dog kibble and meat. 

Behavior: The Gray Wolf is a highly social animal, and their pack size can vary a lot, but are usually made up of 5-12 members.  However, packs can be made up of 20 or more members; these packs often eventually split up into smaller groups.  Packs have complex social structures; there is a dominance hierarchy with a top male or female serving as the pack leader.  Females are just as likely to be the pack leader than males are.  Pack leaders track and hunt prey, choose den sites, and establish the pack’s territory.  Individual positions and interactions within the pack reflect status and privilege. Ranks are also not permanent and contests are most intense during the winter breeding period.  It is suggested that the division of labor in a pack’s social organization involves the females primarily engaged in pup care and defense, while the males primarily engage in foraging and food provisioning.  Within packs, wolves develop strong social bonds and often display deep affection for their families.

Wolves use both chemical and vocal methods to mark territory and communicate.  Scent marking (usually with urine) is mainly used for marking territory, which is site-specific and long-term, while howling is a more immediate territory marker. Marking territories by urine, anal gland secretions, and scratch marks help to avoid conflicts between packs, warning other packs of alien territories. Scent marking can also communicate sex and reproductive state.  Other communication is through facial expressions and posture, such as crouching or rolling over to show the stomach.  These are fixed states of behavior that are recognized by other wolves as conveying moods of alertness, aggression, submission, etc.

Breeding: Gray Wolves breed once a year between January and April, depending on where they live; northern populations breed later in the season than southern populations.  Female and male wolves reach sexual maturity between 2 and 3 years.  A female goes into estrus once a year for 5 to 14 days.  When a female chooses a mate, they usually have a life-long bond and spend a lot of time together.  After mating, the female digs a den (using a cave or tree base) in which the pups are born and where she will raise them for the next several weeks.  The gestation period lasts 60 to 63 days, and a litter will be on average 7 pups.  The pups are born blind and deaf, so they are completely reliant on their parents and pack to raise them.  The time until weaning period is about 45 days.  For the first 3 weeks the female stays exclusively with the pups and then all members of the pack help to raise them. Pups are fed regurgitated food for the first 45 days; afterwards, they are fed meat.  Since all members of the pack care for them, the pups also become socialized and bond with the pack.  At about 10 months old, the pups start to hunt with the pack.

Adaptations: The gray wolf is an excellent runner and its body and limbs are well adapted for this purpose. Wolves are digitigrades, so when they walk only their toes touch the ground.  The front foot has 5 toes; the first toe is rudimentary and does not touch the ground, while the hind foot has 4 toes.  Their canine teeth are also perfect for puncturing and slashing flesh, picking meat off of bones, and their premolars and rear molars are capable of crushing bones.  The wolf’s large, simple stomach is also better adapted to storing food than quick digestion.  It allows wolves to eat up to 20 pounds in one feeding period to take advantage of unpredictable prey availability.  The food is digested mainly in the small intestine (aided by their large liver that secretes bile to help break down fats), and digests all except hair and bones of prey.  Wolves can also fast for up to two weeks while looking for prey: can you imagine doing something like that?

Conservation: Wolves play an important role in ecosystem functioning by controlling natural prey populations. As human settlement increased in the U.S., however, wolves were seen as a threat to livestock and were hunted to extirpation (local extinction) in much of the United States.  Today, there are only 2,600 gray wolves in the U.S., 2,000 of which live in Minnesota.  However, the main cause of recent population decline is habitat destruction by humans.  There have been many programs to reintroduce wolves into protected land and this has greatly increased their chance for survival in North America.  In Canada and Alaska, the wolf population has remained stable.  Canada has 50,000 wolves handled by provincial governments, and Alaska has between 6,000 and 8,000.  In Western Europe, populations have been mostly eradicated, with isolated populations surviving in Poland, Russia, Portugal, Spain and Italy. 

The gray wolf is listed as endangered by the U.S. Fish and Wildlife Service in the lower 48 states under the Endangered Species Act (ESA). The species has been controversially de-listed in few states including Minnesota, Michigan, Wisconsin, Montana, Wyoming, and Idaho.

Miscellaneous: Contrary to popular the belief that wolves are dangerous to humans, there is actually a better chance that a person will be hit by a meteorite than killed by a wolf!  There has been no documented case of any person being killed by a healthy, wild wolf in the United States.  However, according to the Center for Disease Control and Prevention, 10 to 20 people are killed and 4.7 million people are attacked each year by dogs.

 

MORE ON THE EVOLUTIONARY HISTORY OF THE GRAY WOLF

Sources:

http://animaldiversity.ummz.umich.edu/site/accounts/information/Choloepus_hoffmanni.html

http://animals.nationalgeographic.com/animals/mammals/two-toed-sloth.html

http://bristolzoo.org.uk/learning/animals/mammals/two-toed-sloth

http://www.britannica.com/eb/article-218683/sloth

Gould, Edwin; McKay, George. “Sloths” Encyclopedia of Mammals. Ed. Edwin Gould, George McKay.  1 vol. 2nd edition. Weldon Owen Pty Limited. San Francisco. 1998.

http://www.tigerhomes.org/animal/tow-toed-sloth.cfm

http://xenarthra.org