ALPINE CHIPMUNK. Eutamias alpinus (Merriam)
characters.Smallest and palest colored of the Yosemite
chipmunks (head and body about 4 inches long, tail scarcely 3 inches
long). (See comparative measurements in footnote 15, p. 177.) Usual
chipmunk pattern of coloration; sides of body pale buff; tail showing
more yellowish buff than black. (See pl. 3b). Voice: A
wiry, not loud, sweet repeated frequently; this sometimes modified to
whit when uttered more slowly and with emphasis; also a low
resident of Hudsonian Zone, ranging locally into Alpine-Arctic. Recorded
on Mount Hoffmann and on Mount Clark, and from Glen Aulin and near
Vogelsang Lake eastward to Mono Pass and Ellery Lake. Seldom below 8500
feet altitude. Lives chiefly among rocks, sometimes about fallen logs;
climbs trees but rarely.
The Alpine Chipmunk is the smallest and palest
colored of all the chipmunks occurring in the Yosemite section. It lives
habitually at higher altitudes than do the other species. In only one
place was it observed below 8000 feet; the greater part of the
population of the species lives far above that altitude.
Only one other chipmunk, the Tahoe Chipmunk, is found
regularly within the territory inhabited by the Alpine Chipmunk. From
that species the Alpine may be distinguished by its smaller size and
paler tone of coloration and by its marked preference for the rocks.
(Sec pl. 3b). Furthermore, alpinus shows much less
curiosity than does its relative. If the observer makes a squeaking
noise with his lips, the Tahoe Chipmunk will usually be attracted to
investigate, whereas the Alpine Chipmunk will either pay no attention
whatsoever or else hasten away.
Along the eastern margin of the range of the Alpine
Chipmunk is to be found the Mono Chipmunk, a species of only slightly
larger size but of somewhat more brilliant coloration. Both may be seen
about rocks, and then only close scrutiny of individuals will enable an
observer to distinguish between the two. However, alpinus has not
been found east of Warren Fork of Leevining Creek and Mono Pass and
monoensis is not known to occur west of those stations. At Glen
Aulin the range of the Allen Chipmunk meets that of the Alpine. But the
latter is only about half the bulk of the former and its coloration is
obviously lighter, so that no difficulty will be experienced in
distinguishing these two species.
The range of the Alpine Chipmunk comprises chiefly
the Hudsonian Zone, including the 'tongues' of that zone which extend
westward from the main Sierran crest to such outstanding peaks as Mount
Hoffmann and Mount Clark. The species ranges upward beyond the limits of
the main forest, and in a few instances was noted above the highest
indication of timber line and hence within the Arctic-Alpine Zone. For
example, one was seen at 11,500 feet altitude on Parsons Peak.
This species inhabits for the most part rocky
situations, either the large masses of slide rock on the cañon
sides or the scattered boulders within the rather open stands of
lodgepole pine. Not infrequently it is seen scampering over and about
logs lying on the ground, and in a few instances individuals were seen
in trees. On Mount Hoffmann an Alpine Chipmunk was seen 3 feet above the
ground in a white-bark pine, and another at Ellery Lake was 6 feet up in
a lodgepole pine; at Young Lake one of the animals was seen to climb
several feet up into a lodgepole pine on the lake shore. But the rock
piles constitute the accustomed habitat; individuals traverse these with
great facility, and venture much farther into such places than do the
Tahoe Chipmunks. Although we found no nests, we believe that the Alpine
Chipmunk finds its shelter and suitable breeding dens either amid the
rocks or in the ground beneath them.
Bearing in mind the liveliness of chipmunks in
general, the Alpine Chipmunk must be put down as exhibiting the extreme
of agility, so nimbly and lightly does it skip about from place to place
in carrying on its daily activities. When running on the ground it
usually holds the tail up vertically and so gives the impression that
this member is larger and longer than actual measurements show it to be.
When a chipmunk is perched on some rock, and calling, its tail is
usually jerked upward at the instant each note is given.
This chipmunk does not seem to be so talkative as
some of its relatives. Certainly upon many occasions when the presence
of an observer would provoke other species to loud and persistent
chipping, alpinus gave few or no notes. Its calls as compared
with those of the Tahoe Chipmunk are fainter and higher pitched. Once
learned by an observer they can be used with considerable certainty in
identifying the species. A common call is a repeated sweet, sweet,
sweet, etc., with rather short intervals between the notes and
continued for varying lengths of time. If badly frightened a chipmunk
will utter a startled whip-per'r'r as it runs to shelter. On
occasion a low chuckling note is given, similar to the hollow-sounding
'barks' of the larger species.
The Alpine Chipmunks, despite their boreal home, are
active through a rather long season. Our earliest contact with them
seasonally was on June 28, 1915, when a number were noted on Mount
Hoffmann. As the breeding season was then well advanced or nearly over
it seems likely that they had begun to be active much earlier in the
year. On October 11, 1915, several of the animals were seen still abroad
in the vicinity of Ten Lakes. At Tuolumne Meadows we were told that
during a storm in mid-September the Alpine Chipmunks had taken to cover,
but that they had reappeared as soon as snow ceased to fall. The
individuals seen on Mount Hoffmann were, in several instances, running
across the snow banks. Judging from observations made elsewhere upon
other species of chipmunks, it seems probable that weather rather than
temperature alone is the determining factor in limiting the season of
activity for the Alpine Chipmunk.
The time of mating is unknown. Two females collected
June 30, 1915, contained 4 and 5 large embryos, respectively, and others
captured between July 5 and 17 had been recently suckling young. Males
collected in July gave evidence that the period of sexual activity was
well past. On July 30, young individuals were abroad around Tuolumne
Meadows. A young female weighing 19.5 grams, which is only about half of
the weight of an average adult, was collected at 10,500 feet altitude on
Mount Florence, August 20, and two individuals obtained on Mount Clark
on August 22 were scarcely two-thirds grown. By early October
young-of-the-year had reached nearly or quite the size of adults.
The Alpine Chipmunks obtained at the end of June and
in early July are passing from the much worn and dulled winter pelage
into the more brightly colored new coat. By October this new pelage is
completely assumed and is then not only longer and denser but more
grayish in tone than when it first starts to appear.
The habit of pursuing one another, noted of other
chipmunks, is conspicuous in the present species. A pair will go at
great speed, one individual after the other, up over logs and rocks and
down through crevices, the two keeping always only a few inches apart.
This habit is marked long after the close of the mating season. One
explanatory theory states that this practice serves to keep the animals
'in training,' so that when a real menace threatens, as, for example,
when a marauding Least Weasel makes its appearance, a chipmunk will find
itself in optimum condition for escape to some safe refuge. Another
suggestion offered is to the effect that this habit is acquired in order
that when male pursues female for the purpose of accomplishing the
mating act, only the swiftest males will succeed. If swiftness be a
point of advantage to the species, then a sort of sexual selection by
which swiftness will become an accentuated trait, will here be
There is always more or less competition between the
members of a species in the struggle for existence, and considerable
individuality in behavior is exhibited whenever several animals of any
one species are gathered at close quarters, as when they are attracted
by a common food supply. This individuality was illustrated at Tuolumne
Meadows one afternoon in late September, when several Alpine Chipmunks
were seen contesting with one another for possession of some scraps of
bread which had been discarded from a lunch. At first but one chipmunk
was in evidence and he busied himself with a piece of the bread. He was
soon observed by another of his kind who shortly arrived on the scene,
and this second animal made an attempt to gain possession of the piece
held by the first. Being unsuccessful, the second then found another
fragment for himself. Later a third and then a fourth chipmunk arrived.
Only one animal would eat at any particular piece at one time; if
another attempted to join in, a contest would ensue. Sometimes the
original possessor successfully defended his rights, sometimes the
interloper gained control. Just as among human beings, one, for the
time, might dominate the group, another might be bullied about by all,
and the others would hold their ground between these two extremes.
In spite of the seemingly barren appearance of its
chosen habitat the Alpine Chipmunk finds, at the proper season, an
abundance of food in the way of ripe seeds. But the season of harvest is
short and many of the seeds are of very small size; to secure these
seeds in adequate quantity both for immediate use and for storage
therefore requires a rare concentration of effort and a high degree of
industry on the part of the harvesters. This industriousness is fully
apparent if a person takes the time to watch the animals from a vantage
point where his presence does not, through fear or alarm, distract the
attention of the chipmunks. Analyses of cheek-pouch contents are
instructive in this connection also; and the following selections seem
worth placing on record here.
(1) Fletcher Creek at 10,000 feet altitude, September
4: some fragments of a brown fungus.
(2) Colby Mountain at 9200 feet, October 9: two seeds
of pine (thought to be silver pine).
(3) Ten Lakes at 9200 feet, October 8: 47 seeds of a
(4) Ten Lakes at 9200 feet, October 11: 324 seeds of
sedge and 1 of stipa.
(5) McClure Fork at 9200 feet, August 29: 165 seeds
of sedge and 24 of galingale; total 189.
(6) Mount Hoffmann at 10,300 feet, June 30: 388 seeds
of sedge and 1 of pussy-paws.
(7) Mount Florence at 10,500 feet, August 21: 1113
seeds of willow-herb, 1 of pussy-paws, 19 of stipa, 36 of galingale;
total 1169 seeds.
(8) Mount Clark at 10,500 feet, August 22: 27 seeds
of pussy-paws, 1 of rush, 1080 of a very small undetermined seed; total
(9) Mount Florence at 10,500 feet, August 21: 1550
seeds of sedge, 5 of stipa; total 1555 seeds.
(10) Ten Lakes at 9200 feet, October 9: 4796 seeds of
pussy-paws, 174 of sedge; total 4970 (counted seed by seed into groups
of 10 and these into 100's and 1000's).
The seeds of the plant known as pussy-paws
(Spraguea umbellata) seem, wherever obtainable, to be especially
sought after by chipmunks. These seeds are very small (0.7 to 1.2 mm. in
diameter), flattish, smooth, and glistening black; and they prove
exceedingly elusive to human handling. The fact that the mass of seeds
in a chipmunk's cheek pouches is invariably free of chaff or any other
useless material bespeaks a marvelous degree of dexterity on the part of
the harvester. When we note that one load contained practically 5000
seeds, and recall the complicated nature and rapidity of the movements
of the forefeet, lips, and tongue which must be involved in the act of
gathering seeds, our wonder at the effectiveness of the chipmunk's
nervous and muscular organization is beyond expression.