By JOHN VUCETICH
John
Vucetich, a wildlife ecologist from Michigan Technological University,
leads the wolf-moose Winter Study at Isle Royale National Park.
Thursday, Feb. 23
We take off, and soon we’re following tracks on the island’s south shore, a few miles southwest of Lake Halloran. They almost certainly belong to the wolves we’ve named the West-End Duo.
With every step, as a wolf swings its leg forward, it lowers its paw, at first only gradually toward the ground, just grazing the snow with the top of its foot. Then, extending its ankle, toe pads pointed down, the wolf plunges its paw deep into the snow. The next step begins by lifting a paw up high and right out of the snow. So, from the air and under the right snow conditions, a wolf track is one long series of comet-shaped footprints. The grazed snow is the comet’s tail, and the hard step is the comet’s head, pointing in the wolf’s direction of travel. These wolves are heading northeast, and so are we.
After a few miles, we come to a long section of shoreline where wind and sun have left the beach increasingly bare of snow. As the snow patches get smaller, the tracks became more difficult to follow. Eventually we lose the tracks.
We know very little about these wolves that they don’t know much better themselves. We also know little about the specific habits of these two wolves. However, for the past 10 or so generations of wolves at Isle Royale National Park, when they travel northeast along this stretch of beach, they tend to head to Lake Halloran. It’s the easiest place to cross overland from the south shore to Siskiwit Bay. So we fly to Halloran hoping to pick the tracks up again. No luck.
We
fly off to find the Chippewa Harbor Pack. That should be easy, since
the wolves are most likely sleeping at the site of their most recent
kill. If so, we can make those observations quickly and return to spend
the rest of our time looking for the West-End Duo.
After an hour, we return to Lake Halloran and find wolf tracks that hadn’t been there an hour ago. The comet tails are useful, but there’s no substitute for seeing a wolf track at ground level. So we land, taxi to the tracks and, without getting out of the plane, confirm their direction — northeast, as we thought. The duo is not far ahead.
We take off again and follow their tracks for another mile along the open ridge that extends northeast from Halloran. The tracks disappear at the end of the ridge into a small patch of cedar trees. We circle and circle, straining to see where beneath the forest canopy the tracks lead next. Nothing. Have we lost their trail, or is this where the tracks end, with the wolves resting in the cedars?
We are almost out of fuel. In the time it takes to refuel, the West-End Duo changes directions, emerging onto Siskiwit Bay. Don and Rolf watch the pair walking side by side, shoulder to shoulder. Tracks indicate that they have done so for several miles.
That behavior is significant. Wolves usually walk one after the other. Sometimes it reflects the ease of walking through the snow in another’s footsteps. Sometimes it reflects the pack’s hierarchy. Wolves in courtship, however, are peers — equals in the pack. And a wolf in courtship must show unequivocal interest. Courting wolves frequently walk shoulder to shoulder in the days just before and after copulation. It’s a subtle sign, but we recognize it immediately. We are excited by the prospect.
Friday, Feb. 24
In the late afternoon, we go out for a short flight. Don and Rolf find the West-End Duo bedded a few miles farther down the shoreline.
When
the wolves stand up, the larger, presumably male wolf moves over to the
smaller, presumably female wolf. He places his nose at her rear end.
She accommodates by holding her tail to the side. Female wolves are
fertile for a very short time. To avoid missing that time, a male wolf
regularly sniffs for the scent of hormones.
Meanwhile, the wolves in the Chippewa Harbor Pack do what they mostly do. They sleep at the site where, four days earlier, they killed a calf.
Saturday, Feb. 25
It is windy, but we’re anxious to catch up with the West-End Duo. A storm is expected tomorrow. We’ll almost certainly have difficulty finding the wolves after the storm. Also, the winter study is almost over. If we are fortunate enough to see the duo today, it could be the last time until next winter.
In the afternoon, winds subside to levels that are barely tolerable. We fly. On the south side of Mud Lake, just a few miles from the last sighting of the duo, we see the kind of tracks that wolves make during the several minutes when they are joined in copulation. We see them again on the north side of Mud Lake. Later we find the West-End Duo, still shoulder to shoulder, walking southwest toward Hay Bay.
They follow the scent of a moose upwind, a moose that has been foraging on the ridge overlooking Hay Bay. The moose detects the wolves while they are about 40 meters away. They stop and consider a chase. The moose does not give an inch. After about a minute, the wolves move on.
A few minutes later, they disappear into the forest, perhaps for the last time, as far as this winter’s observations are concerned. We wait all throughout the winter study to make the kind of observations that we’ve made the past three days. In the past three years, the Isle Royale wolf population has declined by about two-thirds, and the Chippewa Harbor Pack seems to be struggling. This West-End Duo very well may be the future of the Isle Royale wolf population.
source
John Vucetich
A male and female wolf walk shoulder to shoulder.
Thursday, Feb. 23
We take off, and soon we’re following tracks on the island’s south shore, a few miles southwest of Lake Halloran. They almost certainly belong to the wolves we’ve named the West-End Duo.
With every step, as a wolf swings its leg forward, it lowers its paw, at first only gradually toward the ground, just grazing the snow with the top of its foot. Then, extending its ankle, toe pads pointed down, the wolf plunges its paw deep into the snow. The next step begins by lifting a paw up high and right out of the snow. So, from the air and under the right snow conditions, a wolf track is one long series of comet-shaped footprints. The grazed snow is the comet’s tail, and the hard step is the comet’s head, pointing in the wolf’s direction of travel. These wolves are heading northeast, and so are we.
After a few miles, we come to a long section of shoreline where wind and sun have left the beach increasingly bare of snow. As the snow patches get smaller, the tracks became more difficult to follow. Eventually we lose the tracks.
We know very little about these wolves that they don’t know much better themselves. We also know little about the specific habits of these two wolves. However, for the past 10 or so generations of wolves at Isle Royale National Park, when they travel northeast along this stretch of beach, they tend to head to Lake Halloran. It’s the easiest place to cross overland from the south shore to Siskiwit Bay. So we fly to Halloran hoping to pick the tracks up again. No luck.
John Vucetich
Tracks like these, left by the West-End Duo on Mud Lake, are indicative that these wolves have copulated.
After an hour, we return to Lake Halloran and find wolf tracks that hadn’t been there an hour ago. The comet tails are useful, but there’s no substitute for seeing a wolf track at ground level. So we land, taxi to the tracks and, without getting out of the plane, confirm their direction — northeast, as we thought. The duo is not far ahead.
We take off again and follow their tracks for another mile along the open ridge that extends northeast from Halloran. The tracks disappear at the end of the ridge into a small patch of cedar trees. We circle and circle, straining to see where beneath the forest canopy the tracks lead next. Nothing. Have we lost their trail, or is this where the tracks end, with the wolves resting in the cedars?
We are almost out of fuel. In the time it takes to refuel, the West-End Duo changes directions, emerging onto Siskiwit Bay. Don and Rolf watch the pair walking side by side, shoulder to shoulder. Tracks indicate that they have done so for several miles.
That behavior is significant. Wolves usually walk one after the other. Sometimes it reflects the ease of walking through the snow in another’s footsteps. Sometimes it reflects the pack’s hierarchy. Wolves in courtship, however, are peers — equals in the pack. And a wolf in courtship must show unequivocal interest. Courting wolves frequently walk shoulder to shoulder in the days just before and after copulation. It’s a subtle sign, but we recognize it immediately. We are excited by the prospect.
Friday, Feb. 24
In the late afternoon, we go out for a short flight. Don and Rolf find the West-End Duo bedded a few miles farther down the shoreline.
Rolf Peterson
The male of the West-End Duo inspects the reproductive organs of the receptive female.
Meanwhile, the wolves in the Chippewa Harbor Pack do what they mostly do. They sleep at the site where, four days earlier, they killed a calf.
Saturday, Feb. 25
It is windy, but we’re anxious to catch up with the West-End Duo. A storm is expected tomorrow. We’ll almost certainly have difficulty finding the wolves after the storm. Also, the winter study is almost over. If we are fortunate enough to see the duo today, it could be the last time until next winter.
In the afternoon, winds subside to levels that are barely tolerable. We fly. On the south side of Mud Lake, just a few miles from the last sighting of the duo, we see the kind of tracks that wolves make during the several minutes when they are joined in copulation. We see them again on the north side of Mud Lake. Later we find the West-End Duo, still shoulder to shoulder, walking southwest toward Hay Bay.
They follow the scent of a moose upwind, a moose that has been foraging on the ridge overlooking Hay Bay. The moose detects the wolves while they are about 40 meters away. They stop and consider a chase. The moose does not give an inch. After about a minute, the wolves move on.
A few minutes later, they disappear into the forest, perhaps for the last time, as far as this winter’s observations are concerned. We wait all throughout the winter study to make the kind of observations that we’ve made the past three days. In the past three years, the Isle Royale wolf population has declined by about two-thirds, and the Chippewa Harbor Pack seems to be struggling. This West-End Duo very well may be the future of the Isle Royale wolf population.
source
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