Brain worm infection caused a young moose to wander far south of its normal range late last year, where it died on a farmstead near Sleepy Eye, Minn., after becoming a local attraction, the Department of Natural Resources (DNR) said Friday.
The laboratory finding by veterinary experts at the University of Minnesota solves the mystery of the moose's death, but it didn't surprise state wildlife officials — the parasite damages neurological function in moose, sometimes causing uncharacteristic behavior, said Michelle Carstensen, wildlife health program supervisor for the DNR.
"He had become a local favorite," she said of the 1½-year-old spike-fork bull moose, who had taken a liking to apples. "They had been watching him for a while and one family put him on their Christmas card."
Carstensen said the pathology finding by the U's Veterinary Diagnostic Laboratory doesn't shed any new light on Minnesota's ongoing study of the state's plummeting moose population. Carstensen said the parasitic brain worm is just one of several working explanations for increased moose mortality in the state. Animal biologists are still studying adult moose and moose calves for answers to the puzzle. Meanwhile, results from Minnesota's latest moose population survey are expected soon.
According to the DNR, moose numbers in northeastern Minnesota fell 50 percent from 2006 to 2012, hovering last year around slightly more than 4,000. In northwestern Minnesota, the moose population has nearly been wiped out, to fewer than 100.
Carstensen said the brain worm that killed the Sleepy Eye moose comes from tiny snails and slugs. The parasites live benignly in white-tailed deer and the deer shed the worms in their feces. For the moose to pick up the brain worms, they have to be living in areas inhabited by deer, snails and slugs.