Yellowstone Moose Numbers Dropping

Prior to that afternoon they had gotten along.Yellowstone, at least, scientists are suggesting the
They had an agreement. The dog ignored him; hemoose may have outgrown their food source.
ignored the dog. Suddenly the rules changed.Moose are hard on willows. In many areas the
Alerted by the surprised gasp coming from somewillows, which provide a necessary habitat for
guests to our Western Montana Lodge, I turnedmany species of songbirds, have taken a beating
just in time to see him doing his best to pummeldue to moose and elk browsing habits. However,
my dog, Pete, into the ground.studies have also shown other factors at play in
It was probably earlier guests from Georgia whothe willow decline.
precipitated the change. Intrigued by his size, theIn some places exclosures have been built to
Georgia visitors had frustrated and angered him inprotect willow stands from browsing. These
their attempt to get some 'close up and personal'exclosures allow scientists to compare protected
photos. Obviously, he didn't like such attention.willow growth to stands with no protection. The
Our winter visitor was just one of the manystudy results have not necessarily helped to clear
Shiras Moose who call Montana's Centennial Valleyup the issue. In fact, some studies have shown
home. Moose numbers appear to be on the rise inlittle difference in the condition of the willows
the Centennial and around Island Park, Idaho [inside the exclosures to those outside. "Even after
However, such is not the case in many other29 to 33 years of large herbivore protection,
areas. Yellowstone National Park, Grand Tetonthere were no new willow recruits or individuals,
National Park, the greater Jackson area, sectionsand no expansion on the edges of the willow
of Canada, and several areas in Alaska arestands inside the exclosures." ([ Here again, more
experiencing declines - some quite sharp.factors are at play than the animals which eat the
Moose were first documented in Yellowstonewillows. Most obvious would be the recent
National Park in the early 1880's. Hard to count,drought. However, other factors, such as insects,
due to their illusive and solitary nature, reliableare also suspect.
moose numbers can be quite difficult to verifyOne way or another, there seems to be evidence
with certainty. Although specifics are hard to pinthat the moose have reached a food ceiling in
down, scientists suspect the numbers, which roseseveral areas. One proof scientists point to is the
significantly after 1900, began to decline severaldeclining pregnancy rates. Through recent analysis
years later. Low counts in 1985 confirmed thisof progesterone levels in moose droppings,
theory. By the late 1980's surveys suggested ascientists have determined the current pregnancy
total Yellowstone National Park population ofrate in the Yellowstone area is averaging about
fewer than 1000 moose.75% - compared to 90% in 1966. With such a
While numbers have remained stable across mostdecrease in the reproduction rate, animal morality
of Wyoming, counts in Jackson have also shownwill continue to out-pace animal reproduction.
a sharp decline. Moose numbers dropped to 1,700The premature death of older moose is being
two years ago, down from a high of 3,500 intaken as further proof of the suspected over
1992. Similarly decreasing numbers appear in manyabundance in the greater Yellowstone and Grand
other areas across North America.Teton areas. In seasons of food shortage, the
Why are the numbers increasing in a few areas,old, the weak, and the young are always the first
while they decline in many others? In an attemptto go. Scientists have documented the death of
to answer this question, a handful of researchersseveral older cows in the last few years,
and scientists have latched on to several theories.strengthening the plausibility of the starvation
These include: wild fire (primarily in Yellowstonetheory.
National Park), predation, relocation, hunting, lackHunting, of course, has an impact on numbers as
of feed, or a combination of several issues (andwell. However, as the greatest decline is occurring
probably some yet unknown).with the National Parks which do not allow hunting,
The recent fire in Yellowstone National Parkthis factor would seem insignificant. The number
certainly had an impact on many species, includingof permits issued outside the Parks is determined
the moose. Many scientists expectedby the best estimated moose numbers.
Yellowstone's fire to increase moose habitat.Therefore, hunting would not seem to be a viable
However, this has not been the case. After areason for the current decline. Although most
catastrophic fire the heavy canopy of a maturecertainly it has had an impact in the past - and
forest is depleted. Deciduous plants, includingtherefore has possibly had an effect on where
willows and aspens, which are often crowded outthe numbers are today - it seems unlikely this is
by a mature forest, usually prosper in the nowstill a precipitating issue.
abundant sunlight. However, in Yellowstone, thisAnother possibility, which would explain the
has not been the case. Partly due to elevation,dropping numbers, is the moose are just moving
partly due to a combination of other factors, theto other areas. Certainly they have moved in the
deciduous growth which was expected has notpast. Although it is possible they were residents of
occurred.Yellowstone's northern range before 1882, they
Therefore, instead of increasing moose habitat,were conclusively identified as residents by 1913.
the fire in Yellowstone National Park has greatlyObviously these animals moved to our area from
depleted their food supply -- particularly in winter.somewhere else. Is it possible they are just
In a normal situation, moose browse, primarily onmoving from the Parks and the Jackson area to
willows during the summer and a combination ofgreener pastures - like the Centennial Valley and
willows and subalpine fir during the winter. OfIsland Park? This theory has not been explored to
course, snow depths effect where and whenany degree in the reports I have read. However,
they feed. While the snow is relatively shallow,the difficulty of tracking moose, and their solitary
moose frequent the willow stands on valley floorsnature, add to the challenge of determining if this
and along stream and lake shores. As the snowis a contributing issues.
deepens, they move further up the mountainHere in the Centennial Valley it is the willows, not
side, seeking the heavy tree canopies.the moose, which are declining. Known for many
Thick tree canopies prevent heavy snow build upyears as one of the best places to view moose,
as well as deterring the crust which forms on thethe Red Rock Lakes National Wildlife Refuge is
top of snow exposed to sunlight. These conditionsnow facing "Moose" challenges of its own. On the
allow them to move under the forest canopyfirst refuge moose count conducted in 1944, 35
with greater freedom. In addition, the heavymoose were observed. An ariel count conducted
cover in a mature forest provides the shade andthis last winter put the total closer to 130. Home
moisture required in the summer by theto over 238 species of birds, including the
subalphine fir - a major component of their winterneo-tropical warblers who use dense willow
diet. However, with the loss of so many acres ofthickets for nesting, the refuge is now facing the
mature forest in Yellowstone, they have lost achallenge of controlling moose populations to
majority of their winter food source.protect bird habitat. According to Red Rock Lakes
The fire's damage is something from whichWildlife Refuge [ studies, "Centennial Valley Moose
recovery will take many, many years. Althoughcontinue to be managed with little understanding
the fire provides obvious benefits, and although itof the consequences or appropriateness of
is a natural force of nature which Yellowstone hasmanagement actions. As a potential major
experience before, the results of fire are longpredator of Moose, specifically wolves, colonize
lasting. A catastrophic fire tends to sterilize thethe Centennial Valley, an understanding of Moose
landscape. Often the only tree seeds whichpopulation demographics, movements, and habitat
remain behind are those of the lodgepole pine -use will be vital to managing for the combined
sometimes called the weed tree of the evergreenimpact of natural and anothropogenic factors on
forest. Although after the fire the moose, inMoose ecology." Wildlife specialists at the refuge
desperation, browsed on some lodgepole, this ishave requested funding for increased studies of
not their normal food. Perhaps in 200 - 300 yearsthe moose and their impacts on the local habitat,
we will again see a return of the subalphine fir,but to date this funding has been unavailable.
and thus good moose habitat in YellowstoneNever an easy issue, the job of protecting all
National Park. Nonetheless, the winter foodspecies without over-protecting one species is a
situation, at least in areas most heavily burned,challenging one. Those who love the songbirds
looks bleak for the foreseeable future.might be glad to see the moose decline. However,
However, not all areas which are experiencingthe moose is also an amazing creature which
declining numbers have experienced a recentplays an important role in the ecosystem. Moose
catastrophic fire. Yet, one thing common to mostare considered a 'keystone herbivore.' Plant
areas is a healthy predator population. Grizzlyspecies composition, distribution, and succession
bears are the primary moose predator, butare directly influenced by their dietary
wolves can also bring down a full-grown moose.preferences. This may also influence avian species
And, perhaps more important, wolves are knowncomposition and diversity in areas where moose
to prey on calves. Although many adults in areasreside.
experiencing decline have been collared in anOn the other hand, those who love the moose
attempt to determine what is causing theirmight not realize the impact they have on bird
decreasing numbers, moose calves have not beenhabitat. And, finally, those who love the Grizzly
collared. Therefore, it is difficult to determine howand wolf might not realize these top of the chain
many calves are born versus how many calvespredators can also become dangerous to the
reach adulthood.ecosystem if they are allowed to deplete game
Solitary creatures, moose are hard to monitor, innumbers to such a low point the game animals
the best of circumstances. A semi-accurate countalso become 'endangered.' Clearly the desired
of the young is even harder to obtain. Thus, thecondition is balance.
full predation impact on the declining numbers isMost likely many factors are involved in the
hard to determine. One thing is certain. It is havingsituation we find occurring today. As we know,
an impact.nature tends to cycle. The increase in moose has,
Different areas are handling the situation inat least in some ways, impacted the willows. This
different ways. In Yellowstone National Park andin turn has depleted the nesting areas for many
Grand Teton National Park, the wolf and Grizzlybird species. However, with the current decline in
remain protected by the Endangered Species Act.moose numbers in many areas, might we not see
In other areas, wolf and sometimes even Grizzlya corresponding increase in bird numbers? As
management is handled quite differently. Forstewards of this planet, it certainly places a great
example, in one area of Alaska, wolves haveresponsibility on those in positions of authority to
been shot to help control their impact on theuse great wisdom in protecting the many plants
moose and Caribou populations. Although not aand animals. As we see an increase in willows, will
pretty picture, the wolf, having no naturalthe Moose return? Or will the continued increase in
predator, has the potential of becoming a lethaltop of the chain predators in the greater
weapon if not controlled. This is considered byYellowstone area stymy or possibly even
some, one way to control them.accelerate their reduction? These questions, and
Another theory related to the declining mooseothers like them, will continue to challenge
numbers is starvation. In Grand Teton andscientists world wide for many years to come.