Based on a study conducted this winter, the Department of Natural Resources put the wolf population at 636 — down from 658 last year and 687 in 2012. But based on the way the numbers are calculated, the actual number of wolves could be up to 42 higher or lower than the estimated total, the agency said.
The 2013 count had a confidence interval of plus or minus 56 wolves. The statistical overlap between the two years suggests the population has not measurably declined, said Adam Bump, the DNR's furbearing animal specialist.
"It's essentially the same as it was before," he said.
Population numbers are being watched closely by groups on both sides of the debate over whether to continue allowing wolf hunting in Michigan. The first managed hunt since the species went on the endangered list 40 years ago was held last November and December. Twenty-two were killed, even though the state Natural Resources Commission had authorized a take of 43.
The DNR earlier reported that 23 wolves were killed, but adjusted the number after being unable to verify one of them.
The fact that the population drop over the last year was the same as the number of wolves killed in the hunt was a coincidence, Bump said. For the decline to have resulted entirely from the hunt, all the other causes of wolf deaths — starvation, disease, old age, road kills, poaching — would have to have been the same both years, he said.
Instead of a slump, the numbers suggest the population is leveling off in the Upper Peninsula after years of rapid growth following the animal's return in the late 1990s, Bump said. Once present across the state, wolves had disappeared from the Lower Peninsula by the 1930s and from the Upper Peninsula by 1960.
A number of studies have predicted the U.P. population would hit its "carrying capacity" — the maximum number for which there would be enough territory and food — at 600 to 1,000, Bump said.
The population estimate is based on a survey conducted in winter, when tracks are visible in snow and radio-collared wolves can be observed more easily from the air. But numbers can jump dramatically after pups are born later in the year, only to drop once more as some fail to survive and adults die for other reasons.
Jill Fritz, leader of a group called Keep Michigan Wolves Protected, said the latest figures show that "Michigan's fragile wolf population is still struggling to recover, and it underscores that there's no scientific justification for a hunt."
Bump said the count should have no bearing on whether another hunt is authorized this year because the hunts are meant to reduce conflicts between people and wolves, not to affect the population one way or another.