Isle Royale out of balance: The wolf-moose dilemma | Toledo Blade
FIVE DECADES OF FLUCTUATING WOLF AND MOOSE POPULATIONS predation and what that knowledge can teach us about our relationship with nature. Isle Royale's wolves and moose, people began to ask thoughtful questions that. In our view, media attention and the cultural history of the wolf-moose relationship on Isle Royale have outweighed most scientific qualms about. Isle Royale out of balance: The wolf-moose dilemma Petri dish for the study of the predator-prey relationship between its moose and wolves.
Restocking wolves on Isle Royale is the first time that the National Park Service has intervened in a designated wilderness area to manipulate a predator-prey relationship. We think this is unlikely to happen, because wolves have friends in high places in the scientific establishment and the federal government. In our view, media attention and the cultural history of the wolf-moose relationship on Isle Royale have outweighed most scientific qualms about putting a finger on the ecological scale.
Small bull moose on Isle Royale. Both species have cultural meanings that extend beyond their predator-prey relationship. Moose were first sighted on the island around the turn of the 20th century, and scientists have been examining them continuously since at least the late s.
Listen: Scientists turn wolf-moose relationships on Isle Royale into music | Michigan Radio
Wolves arrived around For decades they could reach the island by crossing over ice from the mainland in winter. Now climate change is altering ice formation in Lake Superior, leaving wolves on the island isolated. Isle Royale is located in the northwest corner of Lake Superior.
NPS Isle Royale measures just over square miles and is well-suited for ecological research. Animals exist there in relatively small and thus, countable numbers. The island is easily accessible by boat, ski-plane and seaplane, weather permitting. The first wolves were a pair of animals that walked across an ice bridge from Ontario during a particularly cold winter in All of the subsequent wolves inhabiting the island descended from the initial pair, which led to population difficulties resulting from inbreeding.
Investigators initially envisioned that a population equilibrium would have been reached between the predatory wolf and moose prey populations. However, this has not been observed.National Park Service to introduce 20-30 new wolves to Isle Royale
Instead, the wolf and moose populations have shifted antagonistically between high and low points. For example, the moose population which was expected to hover around individuals has ranged between to sincewhereas the wolf population which was expected to hover around 25 individuals has fluctuated between 2 and Mathematical ecology ; Population genetics Scientists estimate that there are only 2 remaining wolves on Isle Royale. As a result, the numbers of moose on the island are increasing at a very rapid pace.
Restocking wolves on Isle Royale raises questions about which species get rescued
Thus, conservationists fear that the growing moose population will eliminate the limited vegetation that they eat and need in order to survive, thereby leading to starvation of the animals.
Vucetich, the lead author of a study of the wolves published online in The Proceedings of the Royal Society B in By the end of his eight years of breeding, he produced 34 pups, those had produced an additional 45 pups.
Scientists expected that such an introduction would create a "genetic rescue" population boom, but it did not happen. Peterson, a research professor at Michigan Technological University, said that the population of Isle Royale hangs on by a thread, as it has for decades.
The average reproduction after the Old Gray Guy arrived was no different from before. Yet this does not mean that he had no effect. Vucetich, an assistant professor of wildlife ecology at Michigan Technological University. It's plausible that we didn't see an effect because the wolves were suffering from some other trouble that disguised the benefit.
What if wolf No. Vucetich said that it is impossible to know for sure, but the Isle Royale wolves might have disappeared completely. It may be that the Old Gray Guy arrived just in time.
Once a moose is brought down and killed, wolves have to compete with scavenging ravens. Ravens are tenacious scavengers that can easily dodge the strike of a wolf and are unbothered by them.
Ravens can eat and store up to two pounds 0. Before wolves hunted them to extinctioncoyotes used to inhabit the island. Beavers and snowshoe hares also have an effect on both populations, because beavers and snowshoe hares are the only two animals that wolves prey on excluding moose, constituting a tenth of an Isle Royale wolf's diet. They are as easy prey for wolves and they create aquatic macrophytesvery nutritional plants for moose, although the macrophytes are also consumed by the beavers.
Beavers have been exposed to predation by having to travel long distances to find only parts of the island where aspen remains. Snowshoe hares, the third most consumed animal by wolves on Isle Royale constitute a very small portion of the wolves' diet, because snowshoe hares are so difficult to catch.