A Wolf-Moose Standoff at Isle Royale

January 31, 2012

By JOHN VUCETICH

 

John Vucetich 

A cow moose remains vigilant while her calf forages for what might be beneath the snow.

John Vucetich, a wildlife ecologist from Michigan Technological University, leads the wolf-moose Winter Study at Isle Royale National Park.

Thursday, Jan. 26

No flying today. Moisture drips from low and lingering clouds. But our ground-based crew is productive. Our field technicians, Dieter Weise and Beth Kolb, snowshoe all day through spruce, over creeks, beneath cedars. They are searching for moose tracks. They find five sets of tracks and follow them to the treasure they seek: pellet piles and yellow snow. The samples will tell us, with help of some chemical analyses, about the pregnancy and nutritional status of those moose.

Rob Bell, a National Park Service employee, snowshoes the Hugginin Loop, recording which balsam firs have survived from last year. The balsam firs are an important source of food for moose.
Each bit of information we collect is like a fragment of papyrus from an ancient text — not very informative by itself, but loaded with insight when the fragments are pieced together in just the right way.
Meanwhile, we take a sauna, not because we need it, but because we have time on our hands.

Friday, Jan. 27

The Flagship is in the air again. We fly for six hours, as the overcast overtakes the sun. We spot the Chippewa Harbor Pack bedded beneath a small clump of spruce on the north side of Mount Ojibway. Thirty meters away stand a cow moose and her calf. The calf’s only defense is staying close to its mother. The cow is apparently too much for the wolves to mount any kind of straight-on attack. But any advantage will be lost if she walks or runs away. So the moose stay. So do the wolves. But for how long? Although they cannot just take what they want, the wolves apparently see merit in waiting. If the mother moose is inexperienced at defending a calf, she might make a mistake in her anxiety-ridden state of mind. Everyone waits. These confrontations occur regularly. A typical moose might stand wolves down several times a year. Sometimes the wolves move on after just a few minutes. Sometimes they remain for days.

We see some wolf tracks near Grace Creek, more on the beach of Siskiwit Bay, and more again near Little Todd Harbor (see map). We’re not sure whether the tracks belong to one or two groups of wolves.

 

 

Blue lines indicate wolf tracks that we observed on Jan. 27.  We’re not sure whether they were made by the same group of wolves or maybe two groups of wolves. Wolves from Chippewa Harbor Pack kept a cow and calf on guard at site A. They killed a moose several days earlier just a mile to the northeast.

Still no signal from the radio-collared wolf Romeo. We’ve resigned ourselves to the possibility that his collar has malfunctioned. If he is alive, he has most likely left his pack. Perhaps he’s among the wolves making tracks at the west end of Isle Royale. When we find wolves, we’ll be looking to see if any wear a collar that doesn’t emit a signal.

Today marks a first for me: I saw more foxes than wolves on a flight. We see four of the small fluffy-tailed creatures. Throughout upper central North America, snowshoe hares are at the peak of their 10-year cycle. While the hares will be starving this winter as their populations begin to drop, it’s a good year to be a fox.
The wind quickly rises to 25 knots. Don wrestles the wind for control of the Flagship. It’s time to go home. The overcast skies bring light snow that soon turns to squalls.

source