People often assume that nature, if left to her own devices,is stable and unchanging. They believe that change is caused by human tinkeringor interference, and it’s always bad.

But this is not the case.

While humans can and do change their environment, they arenot the only causes of change. Some happen naturally. A good example of thishas occurred on Isle Royale, an island in Lake Superior which is now part ofthe National Park system.

Isle Royale is now famous for its wolf and moosepopulations. Because it is quite isolated and only has one dominant predatorand one dominant prey, it is the ideal place to study the relationship betweenthe two species. Durward Allen initiated the Isle Royale Wolf-Moose project in1958. The study is still going on.

But neither wolves nor moose have been on the island forlong, and it is likely that neither are there because of human tinkering orinterference.

In the early twentieth century, the largest mammals on IsleRoyale were the Canadian lynx and the boreal woodland caribou, a subspecies ofreindeer found primarily in Canada with small populations in the United States.Archeological evidence indicates both of these species had inhabited IsleRoyale for 3,500 years. Their demise on the island can be attributable to humanactions such as hunting and trapping and loss of habitat through mining,logging, and fires. But it is likely that the arrival of competitors alsocaused the lynx and caribou population to dwindle to nothing. Those competitorsarrived on the island not by human intervention, but by their own initiative. 

It turns out that Isle Royale is not as remote as it would seem.At least, not throughout the year. The 14 miles between the Minnesota shorelineand the island may be impossible to swim for most species, but it can be easilytraveled when the water freezes over. Lake Superior last froze over completely in 1996. In 2014 and 2019,ice covered over 90% of the lake’s surface. Ice bridges, narrow pathways of icethat can reach from the mainland to the islands, are more common.

Ice bridges are probably how coyotes managed to appear onthe island around 1905. Often called brush wolves in the diaries and accountsof Isle Royale Islanders, these canine predators ate snowshoe hares, squirrels,and other small mammals. This put them in direct competition with the Canadianlynx, whose numbers declined until it was believed to be completely gone fromthe island by the 1930s. However, there have been occasional sitings of lynx,the most recent being in 1980. Whether there was a small resident population ofreclusive lynx or the cats crossed back and forth over ice bridges is up fordebate.

Moose first arrived on Isle Royale soon after coyotes, with1909 being the most likely year. There are several theories about how the bigmammal came. Some suggest that they were stocked on the island for the purposeof recreational hunting. This seems unlikely. If someone had managed to captureand cage several moose, then transport them to the island, they would have leftsome sort of documentation; managing such a feat with so large and bad temperedan animal demands serious bragging rights. Other sources suggest that moose swamacross Lake Superior from Minnesota,

and while a long distance, moose arestrong swimmers and this could be possible. It is more likely that moose usedan ice bridge to reach Isle Royale, just as the coyote had. Moose and cariboucompeted for the tender shoots and buds of willow, aspen, and birch untildeciduous trees were largely eradicated. The last boreal woodland caribou onIsle Royale was documented in 1925. Now, moose rely on balsam fir and, whenother food sources are overgrazed, lichen. For fifty years, their numbersfluctuated in a boom-and-bust cycle, rising when weather conditions were good andfood abundant and declining in years of scarcity and harsh weather. And thenwolves came.

In 1949, during a particularly harsh winter, wolves crossedan ice bridge from Ontario to the island. No one is sure just how many wolvesarrived, but it could have been a single pair. Wolves flourished on the largemoose herds, outcompeting the coyotes, who disappeared within a few years.

Without much (or any) human intervention, three species: thelynx, the caribou, and the coyote had left the island and the moose and wolfhad taken their place.

In 1958, when Durward Allen initiated the Isle RoyaleWolf-Moose project, he and other ecologists expected to document a “balance ofnature” in which the wolf and moose populations became relatively steady inrelation to each other. They believed that when moose herds increased, wolfpopulations would also. What actually happened was much more complicated. Themoose population has ranged from as low as 500 to as high as 2500. The biggestdrop in population came in 1996, when the most severe winter on record and anunexpected outbreak of moose ticks caused the population to collapse. It seemsdisease can affect moose populations as much as predation from wolves.

Wolf populations have been erratic as well, ranging as highas 50 to an unsustainable two. In 1980 the wolf population crashed after humansinadvertently brought the disease canine-parvovirus to the island.  By thelate 1990s, it was clear that the small number of wolves that had begun theisland’s packs had led to inbreeding, which was weakening the individuals. In 1997,a single male wolf crossed from Ontario on an ice bridge, reinvigorating thegene pool. It appears that in 2008 two wolves left the island the same way.

By 2017, when there were only two wolves left of the island,authorities decided to step in and help nature restore her balance. After somedebate as to whether the introduction was an unnatural intervention, fourwolves were brought from Minnesota in 2018.  The next year, another 15 wolves were releasedat Isle Royale in hopes of bringing stability to the ecosystem.

As of early 2024, the wolf population on Isle Royale isestimated to be around 30 wolves, which represents a stabilized population in fourdistinct wolf packs. Now, Park Service wildlife biologists are talking aboutbringing back the lynx.

My historical novel, Perspective, is set in the 1930s, so the moose was on the island, but the largest predator was still the coyote. It tells the story of Genevieve Williams, an artistic 12 year old girl who is put on a ferry to Isle Royale to live with a father she's never met. Genevieve has one terrifying encounter with a moose early on in the story, but learns to love the ungainly animals and the wild beauty of the islands. When the government decides to create a national park on the island, Genevieve tries to come up with a plan that will allow her and her father to stay. The novel, written for middle grade readers and up, will be published in early october and is presently available for pre-order.