Ecologists have studied the wolves and moose on Isle Royale, a remote island in Lake Superior, for more than 50 years. As we report on page 140, after decades of isolation and inbreeding, the wolf population may be on the verge of dying out. The US National Park Service, which manages the island, is moving slowly in deciding how to proceed. It has three options: total non-intervention; reintroduction of wolves only after the current population has hit zero; or pre-emptive genetic rescue by bringing in wolves from the mainland to diversify the gene pool. Arguments for non-intervention tend to rely on the perceived need to let nature take its course. This is nonsense. The whole system is highly artificial: wolves and moose have been on the island for less than 100 years, and human activity has been key to the wolves' decline. A previous wolf-population crash in the 1980s was caused by a disease transmitted by a domestic dog. Anthropogenic climate change is almost certainly reducing how often ice bridges form to the mainland, which makes it hard for new wolves to come to the island. Some even think that humans put moose on Isle Royale in the first place.
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