Moose population decline continues in northeastern Minnesota

Bad news continues for Minnesota’s moose population, According
to results of an aerial survey released Monday by the Minnesota
DNR, the moose population in northeastern Minnesota continues to
decline.

Survey results revealed lower moose numbers and the proportion
of cows accompanied by calves continued a 13-year decline and
dropping to a record low of 28 calves per 100 cows.

“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 populations are estimated using an aerial survey of the
northeast Minnesota moose range. Based on the survey, wildlife
researchers estimate that there were 5,500 moose in northeastern
Minnesota. The estimate, while not statistically different from
last year’s 7,600, reinforces the inference that the moose
population is declining. In addition to the decline in the calf to
cow ratio, the bull to cow also continued to decline with an
estimated 83 bulls per 100 cows. Aerial surveys have been conducted
each year since 1960 in the northeast and are based on flying
transects in 40 randomly selected plots spread across the
Arrowhead.

A study of radio-collared moose in northeastern Minnesota
between 2002 and 2008 determined that non-hunting mortality was
substantially higher than in moose populations outside of
Minnesota. Lenarz indicated that, “combined with the reduced number
of calves, the high mortality results 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, 103 have
subsequently died, most from unknown causes thought to be diseases
or parasites. Nine moose died as a result of highway vehicle
accidents. Two were killed by trains. Only six deaths were clearly
the result of wolf predation.

Analyses by Lenarz and other scientists have indicated a
significant relationship between warmer temperatures and
non-hunting mortality. “Moose are superbly adapted to the cold but
intolerant of heat,” said Lenarz, “and scientists believe that
summer temperatures will likely determine the southern limit of
this species.”

As recently as the 1980’s as many as 4,000 moose inhabited
northwestern Minnesota, an area of agricultural land interspersed
with woodlots. The population declined dramatically during the
1990s and currently numbers fewer than 100 animals. In contrast,
the northeastern population occurs in wetland-rich forested habitat
which presumably provides thermal cover in a warming
environment.

 In August, a Moose Advisory Committee convened by the DNR
released their findings which will be used in the development of a
legislatively-mandated research and management plan. They indicated
that while climate change is a long-term threat to the moose in
Minnesota, moose will likely persist in the state for the
foreseeable future. The plan should be ready later this spring and
will be open to the public for comment.

The Fond du Lac band of Lake Superior Ojibwe and 1854 Treaty
Authority contributed funding and provided personnel for the annual
survey.

Categories: Rob Drieslein

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