Impacts of Oil Exploration and Drilling
on Muskoxen
Muskoxen (Ovibos moschatus) were
driven to extinction before the 20th century. They were reintroduced
in 1969 and their numbers reached a peak at almost 400 individuals in 1986.
Since then, the muskoxen population has declined to around 200 individuals.
Reasons for this population decline include emigration, increased predation
by grizzly bears, and severe winters. Also, hunting by humans has increased
since their reintroduction. (Patricia E. Reynolds, Kenneth J. Wilson, and
David R. Klein, 2002)
Population dynamics of Muskoxen
Graph: http://www.absc.usgs.gov/1002/images/Fig07-01.gif.
Muskoxen conserve energy by limiting their movement; they tend to stick
to a core area about 50 km2 in the winter and 200 km2
during the calving and summer seasons. Calving occurs from March to
June, so it is especially important for mothers to build up enough reserves
during the summer to last the winter and to feed the newborn. Thus,
a prolonged winter would have significant negative impacts on calf survival.
Muskoxen depend on riparian cover along river corridors, floodplains,
and foothills year-round. During the winter, it seeks out areas of
soft shallow snow. Its winter diet consists mainly of low-quality forage
such as sedges, grasses, mosses, and forbs. In the spring, it feeds
on high quality flowering sedges. Muskoxen tend to be very loyal to
a particular spot, returning there year after year. (Patricia E. Reynolds,
Kenneth J. Wilson, and David R. Klein, 2002)
Muskoxen herd
(Photo: http://www.saskschools.ca/%7Egregory/arctic/Amuskox.html)
Any human activity should stay away from the muskoxen habitats, including
adjacent uplands. The areas that muskoxen frequent are places often
used for gravel and water extraction for roads and/or platforms. Muskoxen
congregate into larger groups in the winter, and large groups of animals are
more likely to be disturbed by human activity because they tend to have more
sensitive individuals.
Muskoxen groups that have moved west tolerate the Trans-Alaskan pipeline
and the Dalton highway, but it is due to the wider area of habitable land
available to the animals. Muskoxen remaining in the 1002 coastal plain
are in a more geographically constricted habitat, with the Beaufort Sea to
the north and the Brooks Range to the south. Eastern muskoxen populations
are likely to suffer if human activities displace their territories and there
are few alternative habitats available. (Patricia E. Reynolds, Kenneth J.
Wilson, and David R. Klein, 2002)
Range expansion of muskoxen
in mixed-sex groups in and near the Arctic National Wildlife Refuge, Alaska,
1969-1993. Total ranges were defined by 95% adaptive kernel contours.
Core areas were defined by 70% adaptive kernel contours.
(Map: http://www.absc.usgs.gov/1002/section7part1.htm)
As muskoxen populations in the far west have coexisted peacefully with
the Trans-Alaskan pipeline, a similar pipeline through the 1002 region should
have little impact as well-- if it is built with the same environmental precautions.
For example, the Trans-Alaskan pipeline has 579 animal crossings over its
800 mile span.
Helicopters and low-flying aircraft have been noted to cause some herds
to stampede and abandon their calves. Some herds have been agitated
by 3-D seismic exploration as far as three kilometers away; other herds seem
unperturbed as close as 300 m. Generally, noise produced by traffic,
etc will have a negative effect on the animals. (Patricia E. Reynolds, Kenneth
J. Wilson, and David R. Klein, 2002)
Little data are available on the interaction between muskoxen and human
settlement associated with oil development. This is because drilling
platforms have been built in regions rarely visited by muskoxen. However,
the nature of the muskoxen's normal food source is such that its scavenging
among human waste is unlikely. The major concern is the gravel used
for the platforms, which would have to be extracted from muskoxen habitats.
The specific impacts of seismic exploration on muskoxen:
The population of muskoxen in the 1002 area is approximated to be about
250 muskoxen living all year long. The survival of muskoxen is
influenced by environmental conditions such as the depth of snow, which
is in turn greatly influenced by seismic exploration activities. In
general, the following effects are feared if exploration is to be
conducted in the 1002 area:
a. Displacement of muskoxen from their winter habitat.
b. Due to this displacement, there will be greater energy needs.
Muskoxen need to reduce their activity and movement during the winter in
order to preserve their energy and survive.
c. Decreased body fat in females. This body fat must be maintained
during the winter if they are going to rear a calf.
d. Greater chances of predation.
e. As a consequence of the above, there will be decreased calf
production and less survival of the animals.
Impacts of Oil Exploration and Drilling on Lemmings and Voles
Lemmings and Voles tend to be more abundant and have less survival issues
than muskoxen. In the winter they live in large underground burrows
that may be as close as two inches from the permafrost. They subsist
on willow twigs, sedges, and stored tubers during the long winter season.
Burrows of voles are often raided by native peoples, who pilfer the stored
tubers for their own use. (John Whitaker Jr., 1996)
Because of their numbers lemmings and voles are not likely to be wiped out
by human activity in the region. However, they are an important source
of food for higher lever consumers, including polar bears, wolves, and foxes.
Lemming cycles, for example, are closely tied to the population cycles of
various predators. A sharp drop in their numbers could potentially cause
a population decrease in many other, higher-level consumers. (John Whitaker
Jr., 1996)
Reference:
1. Patricia E. Reynolds, Kenneth J. Wilson, and David
R. Klein. (2002). Section 7, Arctic Refuge Coastal Plane Terrestrial Wildlife
Research Summaries
http://www.absc.usgs.gov/1002/section7part1.htm
http://www.absc.usgs.gov/1002/section7part2.htm
2. http://www.absc.usgs.gov/1002/section3part3.htm
3. http://books.nap.edu/books/0309087376/html/117.html
http://www.jpo.doi.gov/pthom/Environmental%20Report.pdf
Oil or Animals report
4. John Whitaker Jr. (1996). The National Audubon Society
Field Guide to North American Mammals