Minnesota's moose herd is still shrinking, despite the cancellation of this year's sport moose hunt.
Department of Natural Resources researchers in northeastern Minnesota found more than two-thirds of young moose they tracked died in the first four months of life, the Duluth News Tribune reported Friday.
Of the 49 calves fitted with GPS collars in May shortly after they were born, four slipped their collars and 11 died of complications immediately following their capture, mostly because they were abandoned by their mothers, researchers said.
Twenty-four of the remaining 34 calves died within four months. Sixteen were killed by wolves, four were killed by bears, two were abandoned, one drowned and one died of unknown causes.
"As they get bigger, their chances get better. But they still have all of winter to get through." Researcher Glen DelGiudice said.
The mortality rate of the group of calves tracked by the DNR was 71 percent, which far exceeds the roughly 55 percent rate that is normal for moose populations that live alongside predators. The rate varies based on predator-to-prey ratios in certain areas, "but we would hope to have about a 45 percent calf (survival) rate after one year," DelGiudice said.
Northeastern Minnesota's adult moose population is also shrinking, but at a slower rate. Of 107 adults collared by the DNR last winter, 19 have perished. Nine of those were injured or killed by wolves, though researchers said at least three appeared to have health problems that made them more vulnerable. Five others died of assorted health problems, while 5 died of undetermined causes.
Northeastern Minnesota's moose population was thriving 10 to 15 years ago, and numbered more than 9,000 as recently as 2006.
The DNR doesn't believe wolves are the primary reason the moose herd shrank so quickly, but they may now be contributing to the decline, DelGiudice said. That's because the wolf population has stayed fairly level while the moose herd has diminished, changing the predator-to-prey ratio, he said.
The DNR and tribal resource agencies canceled this year's moose hunt for the first time in decades, after aerial surveys showed moose numbers plummeted 35 percent in one year.
The decline of northeastern Minnesota's moose herd recalls an earlier decline in the northwestern part of the state, which saw its own moose population plummet in the 1990s from about 4,000 animals to just a few dozen. Scientists who studied that decline concluded that a warmer climate had compounded multiple other problems that included disease, malnutrition and parasites.
In an earlier version of this story, The Associated Press erroneously reported the size of the state's wolf population. The state is believed to have about 2,200 wolves, not about 9,000 wolves. This story has been updated.