The grey wolf - endangered or not? Credit: Punchstock

While legal battles continued this week in America over whether the grey wolf is an endangered species, a parallel argument over Canis lupus is playing out on the pages of a high-profile biology journal.

At issue is whether the wolf currently roaming the western Great Lakes area — encompassing Minnesota, Wisconsin, Michigan and parts of Canada — deserves a place on the endangered species list. Some conservation biologists argue that wolf populations have recovered, and are no longer endangered; whereas others suggest that the wolves are not actually the same species as those which were lost (see 'Canis what?').

After more than a century of being hunted, wolves were placed on the US endangered species list in 1973 when their numbers dropped to just a few hundred. The population in the Great Lakes region subsequently bounced back to around 4,000 individuals, and they were removed from the list in 2007 after the US Fish and Wildlife Service (FWS) declared them a 'distinct population segment'.

But a case brought by the Humane Society of the United States saw the Great Lakes wolves returned to the list at the end of last month by a court in Columbia, on the grounds the FWS did not follow proper legal procedure.

And earlier this week a court in Montana put a different population of wolves in the northern Rocky Mountains back on the endangered species list after environmental groups successfully overturned a federal decision to delist them earlier this year.

Crying wolf?

Conservation biologists are still divided over the Great Lakes decision. Robert Wayne of the University of California, Los Angeles, and Jennifer Leonard, now at Uppsala University in Sweden, published a genetic analysis last year showing that the current wolves of the Great Lakes area are largely a mix of the grey wolf (Canis lupus), the coyote (Canis latrans), and hybrids of the two. Only 31% of the wolves there today are the same species as the original population — which they term the Great Lakes wolf and whose genetics they established using 17 samples from around 100 years ago1. Their conclusion: "the pre-recovery population has not been restored", and the Great Lakes wolf belongs on the endangered species list.

But the claim is refuted in a response published this week in Biology Letters2. David Mech, a researcher with the US Geological Survey's Northern Prairie Wildlife Research Center in Jamestown, North Dakota, says that Leonard and Wayne are "crying wolf".

"The Federal Government spends millions of dollars on the wolves when they could be used on other species," says Mech. "If the animal is recovered, as I believe the wolf is, the money could be better spent on other species." Mech says that Leonard and Wayne's survey missed Great Lakes wolves living there today. He also says that the study used a small and geographically incomplete set of historical samples to establish the genetic profile of the original wolf population, introducing a bias into their analysis.

Leonard and Wayne reply in the same issue of the journal, accusing Mech of "wishful thinking"3. "Nearly all genetic studies of wild vertebrates can be questioned to some extent on sampling grounds, but in this case, our conclusion that the historic population contained a greater proportion of unique sequences is robust given our sampling regime and the known history of wolves in the recovery area," they write.

What makes a wolf

Tyler Wheeldon, a masters student at Trent University in Ontario, Canada, is about to weigh in with his own analysis, currently in press with Biology Letters. Using additional historical samples, he concludes that the wolf population in the Great Lakes is fairly similar to its make-up in the 1900s, and thus no longer endangered.

"Today we have a large top predator which is not coyote-like, which is what they wanted to restore," says Wheeldon. "If you have a recovered population that is filling the role of the wolf, we shouldn't worry if it's exactly what used to be there."

This illustrates one of the most contentious issues in conservation biology: what is a species, and what does it mean to restore a species to an ecosystem? The debate will inevitably rumble on — both in the pages of scientific journals, and in the courts.