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Are wolves to blame for fewer
Minnesota moose?
- Article by: DOUG SMITH , Star Tribune
- Updated: November 1, 2014 - 7:14 PM
The jury is still out on climate change, but more wolves seems to correlate with a decline in moose population.
A days-old moose calf near Isabella, Minn., was fitted with a radio collar. Researchers are trying to find out what effect wolves are having on moose mortality.
Wolves likely have played a bigger role in the decline of
northeast Minnesota’s moose population than originally
believed, and there’s no evidence yet that climate change
has been a major factor, according to a new analysis by
renowned Minnesota wolf researcher Dave Mech.
northeast Minnesota’s moose population than originally
believed, and there’s no evidence yet that climate change
has been a major factor, according to a new analysis by
renowned Minnesota wolf researcher Dave Mech.
Mech doesn’t dismiss climate change as a possible factor
in the declining moose herd, but said evidence presented
in earlier research done by the Department of Natural
Resources “just doesn’t hold up.”
in the declining moose herd, but said evidence presented
in earlier research done by the Department of Natural
Resources “just doesn’t hold up.”
Instead, an increasing wolf population in at least part of
the northeast moose range might have contributed to the
decline, Mech and John Fieberg, an assistant professor
at the University of Minnesota, concluded in a recently
published paper. The state’s northeast moose herd has
fallen 50 percent since 2006, to an estimated 4,350 animals
last winter.
the northeast moose range might have contributed to the
decline, Mech and John Fieberg, an assistant professor
at the University of Minnesota, concluded in a recently
published paper. The state’s northeast moose herd has
fallen 50 percent since 2006, to an estimated 4,350 animals
last winter.
In the earlier studies, DNR researchers considered the
statewide wolf population stable between 2000 and 2010,
which was correct, Mech said. But they didn’t consider
that the wolf population in an area that Mech has been
studying — which overlaps part of a moose study area
— had increased to the highest levels in 40 years.
statewide wolf population stable between 2000 and 2010,
which was correct, Mech said. But they didn’t consider
that the wolf population in an area that Mech has been
studying — which overlaps part of a moose study area
— had increased to the highest levels in 40 years.
“My data tends to indicate the problem was there were
more wolves,” Mech said in an interview. “But that doesn’t
necessarily mean that’s the only answer. Is there some
change affecting moose that allows wolves to take more
of them, or is it merely that there’s more wolves?”
more wolves,” Mech said in an interview. “But that doesn’t
necessarily mean that’s the only answer. Is there some
change affecting moose that allows wolves to take more
of them, or is it merely that there’s more wolves?”
If wolves are a major factor in the moose decline, Mech
said the DNR could allow hunters to kill more wolves in
the moose range until the population recovers.
said the DNR could allow hunters to kill more wolves in
the moose range until the population recovers.
Michelle Carstensen, DNR wildlife health program
supervisor, who in 2013 began conducting an adult
moose mortality study using radio-collared animals,
said the previous DNR studies looked at overall
mortality,
but researchers weren’t able to determine cause
of death
in most cases.
supervisor, who in 2013 began conducting an adult
moose mortality study using radio-collared animals,
said the previous DNR studies looked at overall
mortality,
but researchers weren’t able to determine cause
of death
in most cases.
“We assumed wolves were accounting for a portion
of
that mortality, but we didn’t know how much,” she
said.
of
that mortality, but we didn’t know how much,” she
said.
But now officials are finding how much impact
wolves
are having on moose mortality. The study radio
collars
alert researchers when an animal has died, and
provide
GPS coordinates so they can be quickly located
and a
cause of death determined.
wolves
are having on moose mortality. The study radio
collars
alert researchers when an animal has died, and
provide
GPS coordinates so they can be quickly located
and a
cause of death determined.
So far in the study, the overall mortality rate is 26
percent,
which is a concern. Normal stable moose
populations
have an 8 to 12 percent mortality rate. Wolves
have
accounted for 55 percent of the mortality (17 of
31 deaths);
the rest died from health issues.
percent,
which is a concern. Normal stable moose
populations
have an 8 to 12 percent mortality rate. Wolves
have
accounted for 55 percent of the mortality (17 of
31 deaths);
the rest died from health issues.
“The level of wolf predation on the adults is well
in line with
what we’d expect,” Carstensen said. “It’s the
overall
mortality [from all causes] that has us concerned.”
in line with
what we’d expect,” Carstensen said. “It’s the
overall
mortality [from all causes] that has us concerned.”
She noted that the northwest moose heard
plummeted
from about 4,000 in the ’80s to fewer than 100
today, and
wolves had nothing to do with that. Those moose
died from
health-related issues, possibly driven by climate
changes.
plummeted
from about 4,000 in the ’80s to fewer than 100
today, and
wolves had nothing to do with that. Those moose
died from
health-related issues, possibly driven by climate
changes.
And, she said, adult moose in the northeast keep
dying in
summer, fall and early winter “when they shouldn’t
be dying.”
dying in
summer, fall and early winter “when they shouldn’t
be dying.”
Carstensen said the results from current ongoing
moose
studies, which also include moose calves, habitat
and diet,
should eventually provide researchers with answers
to the
mystery. “There still might not be a smoking gun; it
might be very complex,” she said.
moose
studies, which also include moose calves, habitat
and diet,
should eventually provide researchers with answers
to the
mystery. “There still might not be a smoking gun; it
might be very complex,” she said.
So far, in a different study involving collared moose
calves, 67 percent of the mortality was due to wolves.
calves, 67 percent of the mortality was due to wolves.
“Wolf predation is probably a little higher than we
expected,” DNR researcher Glenn DelGiudice said.
“But we knew it would be a main source,” he said,
and it’s far too early to draw any conclusions.
expected,” DNR researcher Glenn DelGiudice said.
“But we knew it would be a main source,” he said,
and it’s far too early to draw any conclusions.
He is planning on collaring more moose calves next
spring, and said several years of data are needed.
spring, and said several years of data are needed.
Mech’s latest report says the northeast moose
population was relatively unaffected by wolves from
1997 to about 2003 and that wolf numbers tended to
parallel moose numbers. However, after the wolf
population in his study area jumped 81 percent between
2000 and 2006 — from 44 animals to 81 — moose
numbers began declining.
population was relatively unaffected by wolves from
1997 to about 2003 and that wolf numbers tended to
parallel moose numbers. However, after the wolf
population in his study area jumped 81 percent between
2000 and 2006 — from 44 animals to 81 — moose
numbers began declining.
“We don’t know how far and wide that increase [in the
wolf population] took place, but it did in our study area,
and that area was adjacent to the moose study area,
” Mech said. He said it’s reasonable to surmise the wolf
population in the rest of the moose study area also was
rising, rather than remaining stable, as it was elsewhere.
wolf population] took place, but it did in our study area,
and that area was adjacent to the moose study area,
” Mech said. He said it’s reasonable to surmise the wolf
population in the rest of the moose study area also was
rising, rather than remaining stable, as it was elsewhere.
Moose are a prime food source for wolves in the
northeast, so as the moose population declines, one
would expect the wolf population to eventually fall, too.
“That seems to be happening in our study area,” Mech
said. The wolf population there increased until 2012, but
he said it appears to have since declined.
northeast, so as the moose population declines, one
would expect the wolf population to eventually fall, too.
“That seems to be happening in our study area,” Mech
said. The wolf population there increased until 2012, but
he said it appears to have since declined.
The DNR estimated the state’s wolf population last winter
at 2,423, stable from 2013.
at 2,423, stable from 2013.
So if the wolf population in moose country is declining,
will moose rebound?
will moose rebound?
“That depends on what’s going on,” Mech said. “If it’s
strictly wolves, the moose population will recover. But
if there are other factors involved — parasites, disease
or warming temperatures, then it’s hard to say.”
strictly wolves, the moose population will recover. But
if there are other factors involved — parasites, disease
or warming temperatures, then it’s hard to say.”
And if wolves turn out to be a major factor, then the DNR
will have to decide whether to try to lower the population
of one iconic animal to try to boost the population of another.
will have to decide whether to try to lower the population
of one iconic animal to try to boost the population of another.
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