Muskoxen, Lemmings and Voles
Primary-level consumers in ANWR include several species of mammals, as well
as many different insects. However, the insect population of the area
has not been studied very extensively, and it is doubtful that oil exploration
can be detrimental to their survival. Mosquitos and Oestrid flies are
abundant during the summer and are a major nuisance to individuals in the
porcupine caribou
herd. The result is that the animals' foraging time is reduced
as they spend more time avoiding the flies, which decreases their chances
of surviving the winter. Lactating females are especially effected.
The author believes that the insect population will actually increase if
human activities begin in the area, due to the generation of trash and the
decomposition of individuals of other species negatively affected by this
human presence. Since little is actually known about the insects of
the area, we shall concern ourselves mostly with the herbivorous mammals
of the area, the most prominent of which is the muskoxen. Other mammals
include various species of voles and lemmings.
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)
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.
Locations of mixed-sex groups of muskoxen seen during winter and summer surveys
in the Arctic National Wildlife Refuge, Alaska, USA, 1982-1999.
(Map: http://www.absc.usgs.gov/1002/images/Fig07-06.gif,
http://www.saskschools.ca/~gregory/arctic/animals/mox.jpg)
Muskoxen
(Photo: http://www.saskschools.ca/%7Egregory/arctic/Amuskox.html)
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. There are two
species of lemmings in the area: the brown lemming (Lemmus sibiricus) and the collared lemming
(Dicrostonyx groenlandicus). The brown lemming
prefers wetter environments like damp meadows and river or lake shores, while
the collared lemming prefers rockier places. Lemmings live on plants,
roots, berries, and lichens, and stored seeds in the winter.
A lemming; picture located here.
There are two species of voles in the 1002 area: the northern red-backed
vole (Clethrionomys
rutilus) and the singing vole (Microtus miurus)
. The northern red-backed vole feeds on leaves, buds, and twigs.
They are active all winter, making the most of their short lives: by the
end of the summer, all those born before the last year have died. The
signing vole is known for its alarm call, a high pitched trill. Singing
voles are colonial, behaving much like prarie dogs. They feed on stored
tubers during the long winter season. Burrows of singing voles are
often raided by native peoples, who pilfer the stored tubers for their own
use.
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-- population booms and busts every four to five years-- 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.
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.
The National Audubon Society Field Guide to North American Mammals
5. http://www.arctic.uoguelph.ca/cpl/organisms/mammals/Terrestrial/brownlem.htm
http://www.saskschools.ca/~gregory/arctic/Awildlife.html
McGill
University on northern red-backed voles
http://animal.discovery.com/guides/mammals/habitat/northforest/northvole.html
http://www.arctic.uoguelph.ca/cpl/organisms/mammals/Terrestrial/singingvole.htm