Seasons of the wolf
- Article by: DOUG SMITH
- Star Tribune
- September 11, 2012 - 11:48 PM
Though wolves are at the top of their food chain, their survival from Day 1 is a life-and-death struggle -- as it is for all wildlife. Here's a snapshot of their lives:
As fall and Minnesota's first wolf hunt approach, wolves and wolf pups have been living a relatively charmed life. They've been feeding primarily on easy prey: deer fawns born last spring, and some newborn calves and sheep. But food soon will be harder to get.
Pups born last spring now are about 40 pounds, and their puppy teeth have been replaced by the real deal, including 1-inch fangs. By late fall, pups might weigh 50 to 60 pounds and will travel and hunt with the adults, usually in packs of five to six. During summer, the packs weren't as mobile when the pups were young -- the adults stayed near the dens or "rendezvous sites,'' feeding the pups. Soon they'll begin hunting throughout their territory, about 40 square miles per pack.
The shorter fall days trigger the wolves' fur to grow thick to help them weather winter. By mid-November they'll have their full winter coat.
This fall, wolves will face one more obstacle to survival: man.
A make-or-break time, winter can be brutal or a breeze for wolves, depending on snow conditions. Last winter, with little snow, wolves had trouble catching whitetails, their primary food source. But with deep snow, or crusted snow, deer are more vulnerable and wolves can feast.
Wolves can subsist on about 2 1/2 pounds of food per day, but they require about 7 pounds a day to reproduce successfully. A large wolf can eat up to 22 pounds of meat in a short time, but adult wolves can survive for days and even weeks without food.
Healthy wolves can easily handle the subzero northern Minnesota temperatures. They curl up in a ball, like a sled dog, out of the wind and in sunlight, if possible.
But mange, a parasite that burrows into wolves' skin and causes them to lose hair, can be deadly. Sickened wolves can freeze to death or be weakened and killed in territorial clashes with other wolves.
However, winter brings new life: Wolves breed in February.
After a 63-day gestation period, wolf pups are born in April, usually in a litter of four to six, in a den -- a hole in the ground, an old beaver lodge, brush pile or rotted tree. Like any canine puppy, at birth they are small, blind and dependent on adults for survival.
Mortality is highly variable, but can be 40 to 60 percent, with starvation and disease likely the main killers. Besides mange, wolves can be infected with diseases that dogs are vaccinated against, including parvovirus, distemper, Lyme disease and heartworm. But in Minnesota, mange is the greatest threat.
Life is hard: Only about 10 percent of wolves live beyond five years. Lucky ones can survive 10 years or longer. For the adult parents, the focus is on raising those pups. When it comes to food, spring brings plenty.
Deer give birth to their fawns, and cattle drop calves -- both relatively easy pickings for wolves. But this year, under new rules, landowners killed a dozen wolves to protect their livestock.
By June, pups are being weaned and are eating meat the adults regurgitate. Wolves continue to feast on beavers, young deer and moose calves. Over a year, one wolf will eat the equivalent of at least 15 to 19 adult-sized whitetails.
That means with an estimated 3,000 wolves in the state, wolves kill 45,000 to 57,000 deer or more. In comparison, last year a half-million hunters killed 191,500 deer.
Wolves in northeastern Minnesota also will kill and eat moose, as well as beaver and other smaller critters. But their primary diet is deer.
Those young wolves -- male and female -- leave their natal packs when they are 1 to 2 years old and disperse, possibly joining or creating their own packs. They might disperse hundreds of miles away, looking for empty territory or a member of the opposite sex for breeding.
Conflicts between members of different packs are not uncommon, and each stakes out territory. As one biologist said: "Wolves live a hard life.''
© 2014 Star Tribune