As Wolves Diminish, Moose Flourish
By JOHN VUCETICH
John Vucetich
Three hungry wolves from Chippewa Harbor Pack.
Monday, Feb. 20
Chippewa Harbor Pack hunts throughout the night. It’s been 10 days since they last killed a moose. In the past 30 days, they’ve caught only one adult cow moose, one yearling cow and one calf. One of the pack will likely starve to death. Chippewa Harbor Pack entered this winter with six wolves, and it has been three weeks since we’ve seen that sixth wolf. He may have left to look for a mate. Or he may have starved. We do not know. If he starved, he may not be the last.
As morning comes, the wolves walk out of the forest and onto the frozen ice of Moskey Basin. They rest some, then return to the forest to hunt. Within an hour, they find and chase a cow and her calf. Exhaustion is the only result. They come up out of the forest again, to rest on a south-facing ridge. A few hours later, they re-enter the thick stand of fir trees north of Moskey Basin. They find and chase another cow and calf, this time injuring both. But, as night falls, none have eaten, and none have died.
John Vucetich
This chase once again resulted only in exhaustion.
We are excited about the few inches of snow that fell today, meager as it may be. It is the first measurable snow accumulation in a month. Mostly, we learn what’s going on by finding and following tracks in the snow. Without fresh snow, a month’s worth of tracks — moose, otter, foxes and wolves — have accumulated. Wolves walk in their old tracks, in old moose tracks or don’t leave any tracks at all as the snow becomes hard and crusty. The island is our teacher, but the lessons are easier to grasp when she occasionally erases the chalkboard.
I spend the day boiling flesh off the bones we’ve collected during necropsies of wolf-killed moose. Pretty light duty this year — only four necropsies so far this season. When moose escape predation and wolves suffer food shortage, work at the bone pot is a little lighter.
Wednesday, Feb. 22
By late afternoon, the clouds have cleared just enough to permit a flight. With only a couple of hours before nightfall, Don and Rolf take off in the Flagship. They have enough time to discover that Chippewa Harbor Pack has finally killed a moose, probably the calf it injured two nights ago.
The wolves fall asleep with the content feeling that comes from having full bellies. However, that feeling may well be ephemeral. Wolves flourish when old moose are plentiful. Old moose are easier to kill and provide a much larger meal than a calf. Isle Royale wolves are entering a period when old moose will be rare, and it’s likely to last for at least five years. This is the consequence of conditions that occurred about a decade ago. Around the turn of the century, the moose population encountered tough times, and few calves were born for several consecutive years. Now, a decade, or so later, those calves have grown old. But there aren’t many of them.
And what caused the tough times for moose a decade ago? That decline was, we believe, fueled by a combination of hot summers, moose ticks and wolf predation. Nature tends to be complicated this way. What’s happening now is often rooted in what happened many years ago. And it’s never a single causal root, but instead a tangled web of roots. Sir D’Arcy Thompson, a pioneer in biology, summed it up well when he wrote: “It is the principle involved, and not its ultimate and very complex results, that we can alone attempt to grapple with.”
For whatever reason, the hunting difficulties that Chippewa Harbor Pack has experienced are likely to persist. But nature is not well understood from any single perspective. As the wolf population of Isle Royale National Park has been declining for the past several years, moose are doing better and more calves are being born. From the moose’s perspective, these are better days. From the wolves’ perspective, seeds are being sown for better days ahead.
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