Yellowstone is being invaded by mounain goats. This non-native species poses a threat to Yellowstone's alpine as well as bighorn sheep.
- Credit / Author:
- NPS Video by Park Ranger George Heinz
- Date created:
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Mountain Goats in Yellowstone.
It is plain and simple, Yellowstone is an exciting place.
People travel here to experience nature at its purist,
and here in the northeast corner of the park,
at its wildest. The preservation of this 2.2 million
acre wilderness ensures this park will remain
one of our national legacies.
The ability to watch as the drama and the beauty
of this naturally regulating ecosystem unfolds,
makes this park one of our national treasures.
Yellowstone’s beauty reaches well beyond
the geyser basins and the canyons.
Much of the beauty here lies within the competition
that occurs at every level of the wilderness.
We are easily excited about the struggles between
bears and wolves, but are those battles more important
than the effort it takes for an alpine plant to survive?
It is the daily interactions between the different
elements of nature that makes this place so special.
One of our main jobs in Yellowstone is to preserve and
protect the natural features and processes found here.
When those processes involve a nonnative species
it draws attention.
Yellowstone is being invaded;
the mountain goat is moving in.
For visitors, a chance to see or photograph these
charismatic creatures is a rare but treasured event.
Mountain Goats are beautiful,
but here in Yellowstone they are exotic.
For hunting purposes, mountain goats were introduced
into the Absaroka and Beartooth Mountains
during the 1940s and 1950s. Those mountains to the north,
along with the Gallatin Mountains to the west of the park,
provided pathways for the migration of goats into
northern Yellowstone. It is believed that by 1990,
mountain goats had successfully colonized
some alpine sections of the park.
The first and most obvious concern with the arrival of
mountain goats was their interaction with native
bighorn sheep. The greater Yellowstone region
is considered one of the most important core areas
for bighorn sheep in North America and sheep are
highly susceptible to disease transfer from other species.
In 1982, an outbreak of pinkeye killed nearly
60% of Yellowstone’s bighorn population.
Maintaining a healthy sheep population in Yellowstone
is essential. Could the added competition and
displacement by mountain goats be adversely
affecting the rebounding bighorn population?
Wildlife managers have been working to develop an
adaptive management plan that best protects the park.
In 2007, researchers from the Yellowstone
Center for Resources began working with Dr. Ken Aho
to research the effects goats are having on the
alpine regions of northern Yellowstone.
Between 2000 and 2003, Dr. Aho,
now a professor at Idaho State University,
conducted his doctorial research in the park.
He established and sampled 110 plots on nine
high-altitude mountains in the northeast portion
of the park and adjacent National Forest land.
That study looked to describe the plant species
found within Yellowstone’s alpine environment.
He also looked at the different plant communities
and how those were distributed across the landscape.
Anecdotal data from this research indicated that
in areas of high goat use, vegetation cover was lower
and barren areas more abundant along ridgelines.
Wow, it’s windy up here!
The latest study, which began in 2007,
used three alternate sampling techniques to assess the
potential effects of mountain goats on alpine vegetation.
Areas of both high and low goat use were looked at.
Secondly, in 2008 and 2009, Dr. Aho collected vegetation
and environmental data at 152 sites on eight
different mountains. Those plots were in five different habitats:
northface, southface, ridge, snowmelt and plateau.
Plots were established along a gradient of goat use
from high to low. Thirdly, Dr Aho resampled some
of the plots he had studied between 2000 and 2003.
Returning to those plots provided measures
of change over time. During this study
a few things concerned Dr, Aho from the start.
One was the fact that there was considerable trail building
in areas of high goat use; this can lead to erosion.
He noticed goats like the areas just downslope
from the lingering snow cornices;
the melting snow provides water for the goats,
but is also creates important habitat for some
of the rarest plants found in the Northern Rockies;
some of which are endemic to this region.
Also the amount of plant disturbances at
goat bedding sites was significant.
A major concern is the rapid expansion of the
goat population into fragile alpine habitat;
an estimated 178 goats live in Yellowstone in 2010,
compared to 54 back in 2002.
Dr. Aho: Alpine ecosystems in Yellowstone
are important for two reasons. First of all the park
is intended to be a place where natural systems are
preserved intact and the alpine is certainly an important
part of Yellowstone National Park.
Secondly, all the climate models that have been recently
Published concerning Yellowstone, predict the
treelines will move up in altitude and cause the alpine
to be increasing fragmented and made vulnerable.
Overtime, this research will help the National Park Service
as they create an adaptive management plan that is
based on science. It will also aid state and federal
agencies outside of the park as they develop guidelines
and hunting quotas for the regions near the park.