Thursday, March 1, 2012

Scientist at Work; Notes from the Field Continues

February 29, 2012

A Pack of Hungry Wolves

A member of the Chippewa Harbor Pack. 
John Vucetich
A member of the Chippewa Harbor Pack.
 
John Vucetich, a wildlife ecologist from Michigan Technological University, leads the wolf-moose Winter Study at Isle Royale National Park.

Friday, Feb. 17

It is difficult to connect with the mind of another creature. But today, the alpha wolf of the Chippewa Harbor Pack and I are most likely recalling memories of the same event, even if we experienced it from wildly different perspectives.

It’s a windy day, and we fly just enough to find the Chippewa Harbor Pack and to check old kill sites for other wolves. We find two wolves feeding from a kill site just a couple miles northwest of the bunkhouse. The wolves of the Chippewa Harbor Pack sleep beneath the afternoon sun on a south-facing slope near Hay Bay, the farthest that the pack has ventured from its core territory this winter. One can only imagine the memories being recalled by the alpha male as the wolves walked up that ridge overlooking Lake Superior.
One year ago, minus four days, I hiked over this same ridge and then just a quarter of a mile beyond. It was warm and sunny, like today. On a sled behind me, I hauled the 85-pound carcass of the alpha male of the Middle Pack; two days earlier, he had been killed by the alpha male of the Chippewa Harbor Pack.
In the year since, the Chippewa Harbor wolves have not had to defend their territory, as they are the only surviving pack on Isle Royale. You can see why that was a big day for the alpha male of the Chippewa Harbor Pack.


Chippewa Harbor Pack chases a moose and her calf. 
John Vucetich 
The Chippewa Harbor Pack chases a moose and her calf.

Saturday, Feb. 18 

Last night the Chippewa Harbor Pack crossed the Greenstone Ridge to the north side of the island. By morning the wolves were near Little Todd Harbor, traveling northeast back toward their core territory.
We watch them abruptly turn northwest. We can see what they had smelled — a cow moose and calf that had themselves been foraging upwind. It doesn’t look good for the cow and calf. The calf is too far from the cow, and they seem to have different ideas about how to handle the situation. When the wolves rush in, the cow — which is between the wolves and her calf — turns to face the wolves. But only for a second. The calf bolts. If the cow doesn’t do the same, the wolves will run past the cow and kill her calf with relative ease. The cow and calf are also separated by four or five wind-thrown trees, their trunks a crisscrossed mess. The cow hurls herself over the trunks, which are four or maybe five feet off the ground. She catches up with her frantic calf before the wolves do.

Then the chase is on, led by the least experienced of them all — the calf. The cow, capable of running faster, stays immediately behind the calf, no matter what direction the terror-ridden mind of that calf decides to take. Every third or fourth step, the cow kicks one of its rear hooves. One solid knock to the head would kill a wolf.

After a couple of minutes and perhaps a third of a mile, the pace slows. By the third minute, they’re all walking — the calf, the cow and the wolves. The stakes are high for each, but not greater than the exhaustion they share. Eventually they all stop. Not a hair’s width separates the cow and calf, and the wolves are just 20 feet away. She faces the wolves. A few minutes later the wolves walk away.
By nightfall, the Chippewa Harbor Pack has pushed on another six miles or so. As they pass who knows how many more moose, their stomachs remain empty.

Sunday, Feb. 19

The Chippewa Harbor Pack covers only a few more miles through the night. By midmorning we find the wolves traveling northeast through thick, tangled cedars in a drainage just southwest of McCargoe Cove. On at least two occasions in the past month, they tracked and chased the cow and calf that live in this area. Both times, the wolves failed. They almost certainly know half a dozen or more sites where they can find another cow and calf. There must be something about this particular pair. Maybe the mother is inexperienced or old, or maybe the calf is underdeveloped.

Even from the privileged vantage of the Flagship, it is nearly impossible to see the wolves through the dense cedars. Maybe once every third circle, we glimpse one wolf as it passes from one cedar to the next. After quite a few more circles, a moose runs out of the swamp and over an open ridge top. A moment later the wolves appear on the same ridge top, but the moose is long gone. The wolves lie down on the ridge and sleep for several hours. It is entirely possible that the Chippewa Harbor Pack has chased or tested half a dozen moose or more in the past 36 hours. It is not easy to kill an 800- or 900-pound moose with your teeth.

source

**Note: if you haven't kept up with this fascinating series by a noted scientist, you can find past logs here in the back pages of this blog.**

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