Researchers are closing in on the various reasons for the 15-year decline in Minnesota’s moose herd.
Following four years of monitoring adult moose via GPS radio collars, retrieving downed moose within 24 hours of their death, wildlife biologists have been able to unravel most of the mystery as to what has caused so many of Minnesota’s largest herbivore to die in such a short period.
During that time, the DNR has fitted 173 moose with GPS-linked satellite collars. Over this period 47 moose have perished, 66 percent from infection, illness or parasites and the rest killed by wolves.
Researchers recover the body of the animal within 24 hours, often using ATVs, snowmobiles or going in by foot to retrieve the carcass. Helicopters, if available, fly the animal from the woods to vehicles that take the animal back to the research center for an autopsy.
Culprits killing moose identified so far include winter ticks, bacterial infections, liver flukes, brain worms and starvation, along with predation by bears and wolves. Warmer summers are also listed as a concern because moose spend more time trying to cool their body temperatures when it is too hot. It is believed that heat-stricken moose don’t eat enough, which causes starvation during winter when they don’t have enough fat stored to make it through the lean period when it is hard to find food.
But why so many have died in such a short period will take longer to figure out, said moose project leader Glen DelGiudice, who estimates researchers need at least three more years to collect and analyze data while working on a plan to save the moose (Alces Alces).
In other good news, the annual estimated adult moose survival rate for 2016, the fourth year of the study, is 95 percent. Annual survival rates in previous years were 85 percent in 2015, 88 percent in 2014 and 81 percent in 2013.
Moose population numbers peaked in northeastern Minnesota in 2006 when the DNR estimated 8,840 moose were here. Since then, population has declined 55 percent, and since 2012 wildlife researchers have collared and tracked moose to see why they are dying in such large numbers.
During the first half of 2016 six collared moose died, four of them in collisions with vehicles, one to sickness and one from unknown—or unlisted—causes.
Results from the 2016 aerial moose survey indicated that the population change from an estimated 3,450 in 2015 to 4,020 in 2016 was not statistically significant. Northeastern Minnesota’s current moose population could be as high as 5,180 or as low as 3,230.
Calf numbers are also up. In 2016 the DNR estimated that 17 percent of moose were calves, up from the 13 percent estimated in 2015.
This isn’t the first time moose have experienced a significant die-off in the state. During the 1920s and 1930s the herd declined drastically. In 1922 only 219 moose were shot during the hunting season. Following that season the state of Minnesota discontinued moose hunting until 1971. Despite complete protection, many moose died from “moose sickness” or “moose disease,” and their carcasses were readily found over much of the range. During 1935 to 1945 moose numbers were at an all-time low (3,000 or less) as deer rapidly expanded into their range. Moose made a comeback in the 1950s, and by 1971 it was estimated that the state had anywhere from 5,000 to 8,000 animals.
Today researchers are putting together the pieces of the puzzle for what makes a healthy moose herd, and potential answers are many and varied. Increasing the deer hunt would help the moose but anger the deer hunters who would see those numbers drop off. Bringing back a wolf hunt would assist the moose, but the wolves are now protected and can’t be hunted. Allowing fires to burn or adding logging throughout the region are two issues now being seriously considered, but both are favored by some and protested by others.
Meanwhile, the work goes on. And maybe what will be discovered is that this is a large cycle, a natural part of Mother Nature’s plan, something man can help prevent, but not entirely solve.
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