Geography Reference
In-Depth Information
broad tastes and food habits, versatile predators, many rodents, some scavengers, and
unspecialized insects, just as the flora is made up primarily of adaptable, “weedy” spe-
cies.
It may be instructive to look at the components of a typical recent alpine animal
population. The Beartooth Mountains are located about 50 km (31 mi) east of Yellow-
stone National Park. They are roughly 160 km
2
(100 mi
2
) in area, with elevations of
3,300-3,800 m (10,900-12,500 ft). The birds and mammals of this alpine zone have been
studied by Pattie and Verbeek (1966, 1967). Thirteen species of herbivorous mammals
are more or less permanent residents of the alpine zone. These provide the base of the
food chain and include the following species: one pocket gopher (
Thornomys talpoides
),
one ground squirrel (
Sperophilus lateralis
), four voles (
Arvicola, Clethrionomys, Micro-
tus,
and
Phenacomys
spp.), one pika (
Ochotona princeps
), one jackrabbit (
Lepus town-
sendii
), one chipmunk (
Eutamias minimus
), one marmot (
Mannota flaviventris),
), the deer
mouse (
Peromyscus maniculatus
), the elk (
Cervus elaphus
), the bighorn sheep (
Ovis
canadensis
), and the mountain goat (
Oreamnos americanus
) (the last is an old Pleis-
tocene resident reintroduced by humans; see Fig. 8.1). Six species of herbivorous and
insectivorous birds regularly breed above timberline in the area, including the horned
lark (
Eremophila alpestris
), rosy-finch (
Leucosticte afrata
), and water pipit (
Anthus spi-
noletta
), but all abandon the land of their birth and migrate to warmer climates dur-
ing winter. Carnivores include the weasel (
Mustela
spp.), pine marten (
Martes arneric-
ana
), badger (
Taxidea taxus
), grizzly bear (
Ursus arctos
), red fox (
Vulpes vulpes
), coyote
(
Canis latrans
), and bobcat (
Lynx rufus
). With the exception of the weasels and the
martens, these are also primarily summer animals, because the smaller mammals on
which they depend retreat into subterranean and under-snow habitats during winter.
Gray wolves (
Canis lupus
) were here earlier in the twentieth century, were extermin-
ated, but are making a comeback with and without our help. There are seven or eight
species of predatory hawks and owls, including the golden eagle (
Aquila chrysaefos
),
but most of these, too, abandon the area during winter (Hoffmann 1974).
In addition to those species which are truly alpine in nature, others occasionally
wander up beyond timberline. These include about 10 mammals, including the snow-
shoe rabbit (
Lepus arnericanus
), porcupine (
Erethizon dorsaturn
), mule deer (
Odo-
coileus hermionus
), and moose (
Alces alces
). There are between 15 and 20 species of
vagrant birds, including the robin (
Turdus migratorius
), Clark's nutcracker (
Nucifraga
columbiana
), raven (
Corvus
corax), mountain bluebird (
Sialia currucoides
), and pine sis-
kin (
Spinus pinus
). Domestic sheep should also be added to this list, since several hun-
dred are still driven annually to the high country (Pattie and Verbeek 1967). Thus, about
30 species of mammals and 30 species of birds may be present at one time or another
during the summer above timberline in these mountains. The relationships among these
mammals and the trophic web they form are presented in Figure 8.1. This picture is
altered considerably during winter when the total number of species present is reduced
to 15-20.
The species composition, of course, reflects today's conditions. Had we looked at
these mountains before humans came to North America, we would have seen huge,
tall-legged Columbian mammoths (
Mammuthus columbi
); massive mastodons (
Mammut
americanum
); squat ground-sloths (
Nothrotherium shastense
); ox-sized, large-horned
shrub-oxen (
Euceratherium collinum
); long-horned bison (
Bison latifrons
); fleet-footed
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