Moose Population Decline Continues In Northeastern Minnesota
February 25, 2011
Moose numbers estimated at 4,900, down from last year's 5,500.
Minnesota's moose population in northeastern Minnesota continues to decline, according to results of an aerial survey released by the Minnesota Department of Natural Resources (DNR).
Survey results revealed lower moose numbers and the proportion of cows accompanied by calves continued a 14-year decline, dropping to a record low of 24 calves per 100 cows. The proportion of cows accompanied by twin calves was at the lowest level since 1999, which contributed to the record-low calf-to-cow ratio.
"These indices along with results from research using radio-collared moose all indicate that the population has been declining in recent years," said Dr. Mark Lenarz, DNR forest wildlife group leader.
Moose numbers are estimated using an aerial survey of the northeastern Minnesota moose range. Based on the survey, wildlife researchers estimate that there were 4,900 moose in northeastern Minnesota. Last year's estimate was 5,500.
Since 2005, the downward trend in moose numbers has been statistically significant. In addition to the decline in the calf-to-cow ratio, the bull-to-cow ratio also continued to decline, with an estimated 64 bulls per 100 cows.
Aerial surveys, conducted each year since 1960 in the northeast, are based on flying transects in 40 randomly selected plots spread across the Arrowhead region of Minnesota.
A study of radio-collared moose in northeastern Minnesota between 2002 and 2008 determined that nonhunting mortality was substantially higher than in moose populations outside of Minnesota. Combined with the reduced number of calves, the high mortality has resulted in a population with a downward trend.
The causes of moose mortality are not well understood. Of 150 adult moose radio-collared since 2002 in Minnesota, 114 have subsequently died, most from unknown causes thought to be diseases or parasites. Ten moose died as a result of highway vehicle accidents. Two were killed by trains. Nine deaths were clearly the result of wolf predation.
The Legislative-Citizen Commission on Natural Resources has recommended funding a study beginning in 2012 that would concentrate on identifying factors responsible for high mortality.
In August 2009, a Moose Advisory Committee convened by the DNR released its findings, which were used in the development of a legislatively mandated moose research and management plan. This plan is undergoing final internal review and should be available for public comment soon.
The Fond du Lac band of Lake Superior Chippewa and 1854 Treaty Authority contributed funding and provided personnel for the annual survey.