My, What Long Data You Have!

Isle Royale, looking lovely. Photo by the National Parks Service via Wikimedia Commons. Creative Commons info.

Isle Royale, looking lovely. Photo by the National Park Service via Wikimedia Commons. Public domain.

One of the challenges of ecology is that its data take time to exist. If you want to study the offspring of some yeast cells you poked somehow, just take a long lunch break and they’ll be waiting for you in about 80 minutes. Go away for a full day and you’ll come back to the 18th generation of baby yeast cells. (That’s not to say yeast studies are easy, their time investments just come in different forms.) If you want to look over the same number of generations of a larger, longer-lived mammal, you need a longer data history.

So imagine if you had 55 years of data about wolves and moose on a small island. And now imagine if the wolf population was in trouble–small and inbred. Would you sit by and let the wolves die out, or would you try to throw them a life vest? And in either case, how does the value of your data change?

Those are some of the questions being asked on Isle Royale, a small island 15 miles into Lake Superior. But they’re also being asked of you.

Important plot point: moose can swim. Photo by the National Parks Service via Wikimedia Commons.

Important plot point: moose can swim! Wolves, not so much. Photo by the National Park Service via Wikimedia Commons. Public domain.

The island is a little over 200 square miles large, about the size of Guam. It’s a quiet place: the least-visited US national park in the lower 48 and home to just one out of every three mammal species from the mainland. In the early 1900s, moose became one of those species, likely swimming from Ontario. For a few decades, they ruled the roost, until in 1949 a pair of grey wolves made use of an ice bridge to join them.

Ten years later the scientists came, and for every year since then, we have headcounts for wolves and moose on the island. No, really, just click that link to see them charted. It’s the single longest continuous stretch of predator-prey data in ecology.

Data from Isle Royale were crucial to shaping the idea of trophic cascades, as scientists studied the relationship between wolf and moose populations and tree ring size (refresher: wolves keep moose population under control; fewer moose means less grazing so healthier forests). These wolves are special as the only studied population with just one prey species. Isle Royale also taught scientists that wolves tend to prey on old, sick, and young moose rather than healthy adults. Comparing island moose to mainland moose showed the former were smaller, supporting the “island rule” that small animals grow and large animals shrink when stuck on an island. The study has taught conservation biologists dealing with all sorts of animals about estimating population sizes and measuring the genetic importance of newcomers to small populations. There are over 100 scientific papers published on the Isle Royale wolves and moose (including osteoporotic skull lesions in moose and marrow and kidney fat as condition indexes in gray wolves!). It’s impressive no matter how you look at it.

In 1959, the island was home to 20 wolves and about 500 moose. Twenty years later, wolf populations peaked at about 50 individuals. Now there are eight, and no sign of pups. Even worse, the wolves are showing signs of inbreeding: most worryingly, high rates of inherited spine deformities, a few opaque (possibly blind) eyes and stillborn pups have been spotted. That isn’t wildly surprising when you consider that exactly three wolves are known to have migrated to the island: the original pair and, in 1997, a male nicknamed “Old Gray Guy” (portrait here). After just one generation, 56% of the population’s genes were his, and in his decade on Isle Royale, Old Gray Guy fathered 34 wolves. Every wolf now on the island is his descendent.

The National Park Service is considering three approaches to the problem. It would be a controversial decision anyway, but the length of the study makes many scientists’ opinions more heated, and the debates over allowing wolf hunting in the region (Michigan’s wolf population is steadily rising) certainly don’t lower the temperature. Here are the plans being discussed:

  1. “Genetic rescue”: Bring wolves from nearby populations to the island (interestingly, most articles aren’t saying how many; the only number I’ve found is two to four). Pros: not too many animals to move; means scientists can keep adding to their 55 years of data; would learn more about genetics of introducing migrants to small populations. Cons: wolves aren’t always popular; ‘meddling in nature’ draws ire from a variety of philosophies.
  2. Do nothing. There’s a bit of an implication this would be in hopes that an ice bridge will allow migration to the island or birth rates will rise, preserving the naturalness of the data set but also preserving the wolves. Pros: cheapest option; wolves may rescue themselves, and wouldn’t that be convenient!; would be able to study either the effects of either the natural rebound or losing wolves, respectively. Cons: the ice bridge is a risky bet thanks to climate change (after 16 years with ice bridges in the three decades of 1967-1997, there’s been just one since, in 2008); may lose iconic wolf population; rising moose populations may munch forests into bad health.
  3. Reintroduce wolves after the fact if the population does die off. Pros: keep moose from over-nibbling forests; would be able to compare the current wolves with how the newcomers settle in. Cons: any population-specific knowledge the island packs have been passing down (like how to survive on only one food source) would be lost; messy data-wise since there wouldn’t be enough time to study the effects of losing wolves, but there would be no continuity between the new data and the current data.
  4. One suggestion from an outside group argues for bringing in caribou, coyotes, and lynx, the pre-1900s inhabitants of the island. Pro: cool? Cons: super meddling; complicates an ecosystem that is helpful for its very simplicity; poses philosophical question of, if we’re going to try to “fix” ecosystems to make them look like they did in the past, what date do we use?.

I’ll admit, I’m on the fence–it’s a tough set of factors to balance. Perhaps surprisingly, the National Park Service seems to be welcoming the conversation: it’s soliciting comments from the public at So, tell me and then tell them: what do you think is the best way to maximize the value of 55 years of data, 200 square miles of wilderness, and, at last count, eight wolves and 1000-odd moose?


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