Not linked to, for personal use only.
Klein, D.R. 1968. The introduction, increase, and crash of reindeer on St. Matthew Island.
J. Wildlife Management 32: 350-367.
THE INTRODUCTION, INCREASE,
AND CRASH OF REINDEER ON ST. MATTHEW ISLAND
By David R. Klein
Alaska Cooperative Wildlife Research Unit, University of Alaska,
Abstract: Reindeer (Rangifer tarandus), introduced to St.
Matthew Island in 1944, increased from 29 animals at that time to
6,000 in the summer of 1963 and underwent a crash die-off the
following winter to less than 50 animals. In 1957, the body
weight of the reindeer was found to exceed that of reindeer in
domestic herds by 24-53 percent among females and 46-61 percent
among males. The population also responded to the high quality
and quantity of the forage on the island by increasing rapidly
due to a high birth rate and low mortality. By 1963, the density
of the reindeer on the island had reached 46.9 per square mile
and ratios of fawns and yearlings to adult cows had dropped from
75 and 45 percent respectively, in 1957 to 60 and 26 percent in
1963. Average body weights had decreased from 1957 by 38 percent
for adult females and 43 percent for adult males and were
comparable to weights of reindeer in domestic herds. Lichens had
been completely eliminated as a significant component of the
winter diet. Sedges and grasses were expanding into sites
previously occupied by lichens. In the late winter of 1963-64, in
association with extreme snow accumulation, virtually the entire
population of 6,000 reindeer died of starvation. With one known
exception, all of the surviving reindeer (42 in 1966) were
females. The pattern of reindeer population growth and die-off on
St. Matthew Island has been observed on other island situations
with introduced animals and is believed to be a product of the
limited development of ecosystems and the associated deficiency
of potential population-regulating factors on islands. Food
supply, through its interaction with climatic factors, was the
dominant population regulating mechanism for reindeer on St.
St. Matthew Island, 128 square miles in area and located in
the Bering Sea Wildlife Refuge in the north central Bering Sea
(Fig. 1), supports a poorly developed land fauna. Native land
mammals are restricted to a vole (Microtus abbreviatus) and the
arctic fox ( Alopex lagopus ), although a resident population of
polar bears (Thalarctos maritimus) existed there in Recent times
(Elliot 1882). The reindeer on St. Matthew Island were the result
of the release of 24 females and 5 males on August 20, 1944, by
the U. S. Coast Guard (Klein 1959). Shortly afterwards, the Coast
Guard loran station on the island was abandoned and the island
has been uninhabited since then. Specimens taken for study
purposes and those shot by Coast Guard personnel as a
recreational pursuit have been the only harvest from the herd.
With the exception of 10 in 1966, these were all taken during
1957-63 and totaled 105 animals. This paper reports on the
population dynamics and range interrelationships of this island
reindeer herd from the time of introduction through its rapid
increase and crash die-off until July, 1966.
I appreciate the field cooperation of colleagues Dr. Francis
H. Fay, Dr. Vernon L. Harms, Jack Manley, and Gerry Cowan and the
assistance of James Whisenhant and Dr. Detlef Eisfeld. Dr.
Eisfeld also did the analyses of the reindeer ovarian material
and, through discussion, provided useful suggestions for the
interpretation of the data. Sam Harbo provided advice in the
statistical treatment of data.
In a preliminary study made during the summer of 1957, a total
reindeer count was made, sex and age composition of a sample of
the population was determined, specimens were collected, and
range studies were conducted. Results of this work have been
published (Klein 1959). During the summer of 1963 additional work
on St. Matthew Island supplemented the initial study and
completed the picture of the course of population growth during
the interim 6 years, when population density was high and
pressure on the range vegetation was extreme. An attempt was made
to visit the island during the summer of 1965, but transportation
could not be arranged. In 1966 I again visited the island for 3
weeks in late June and July, during which the surviving reindeer
were counted and specimens shot and examined. Skeletal remains
from the die-off were identified by sex and age, where possible,
and measurements were taken of the antlers and long bones of the
Except in 1963, the total counts of reindeer involved a
systematic search on foot of the entire island in as short a time
as possible to reduce the chance of reindeer movements confusing
the counts. Observations usually were made with binoculars and a
spotting scope from the ridge tops which divide the island
transversely into several broad valleys. Sex and age composition
counts were made in conjunction with the total counts and at
other times when conditions were favorable for relatively close
observation, which was essential for this work. Sex of adults was
determined on the basis of the external genitalia and the
relative size of the antlers, and fawns, yearlings, and adults
were determined on the basis of size and body conformity,
although yearlings and adult cows could be differentiated only
under the best of circumstances. In 1963, the total count was
obtained by completely covering the island with two U. S. Coast
Animals taken as specimens were shot from randomly encountered
bands, although some selection was involved in attempting to
secure representatives of all sex and age groups. Weights were
taken with a 200-lb spring scale, which necessitated weighing
heavier animals in segments. Standard body measurements were
taken and samples of the rumen contents were preserved in
formalin for later chemical analysis. The hide, pharyngeal
pouches, and nasal cavities were examined for evidence of warble
fly larvae ( Oedemagena sp. ) and nasal bots ( Cephenempia sp.),
and internal organs were examined for parasites. The entire
digestive tract was examined only when the animals were killed
close to a supply of water, which was necessary for a thorough
Skeletal remains of reindeer encountered during our work on
the island were sexed on the basis of the relative size of the
antlers and the character of the pelves. The pelves of adult
males had characteristic tuberosities on the posterior border of
the ischium and the pubic symphyses were thicker than in the
females. Age was determined on the basis of tooth development and
The vegetation of the island was studied through the use of
point intercept transects and meter-square quadrats in 1957 and
has been reported on earlier ( Klein 1959). Quantitative
evaluation of the effects of the reindeer on the vegetation of
the island was possible through the use of two groups of
meter-square quadrats located in the dry flats, which originally
supported the most extensive lichen stands. Each group of
quadrats included two which were fenced to protect them from
grazing by reindeer and two unprotected plots. Vegetation within
the plots was recorded on the basis of the percentage of the
total ground cover occupied by each species.
RESULTS AND DISCUSSION
The original reindeer were obtained from Nunivak Island and
were all yearlings; that is, just over 1 year of age. Under the
assumed ideal range conditions on St. Matthew Island at the time
of the release, the introduced nucleus herd probably increased at
a rate approaching the theoretical maximum during the years
immediately following. This rate could have been as high as 83
percent the first year if all females bred and produced one fawn
each. Under optimum range conditions, reindeer have been known to
conceive during their first year and have their first fawns when
they are 1 year of age (Palmer 1934, Davey 1963, Skuncke 1967).
The actual rates of increase cannot be obtained since data on a
yearly basis are not available. Fig. 2 shows the population
growth from known counts, from the time of introduction to the
summer of 1966.
Age composition counts made in 1963 indicate that the reindeer
were experiencing a deceleration in their rate of population
growth at that time. In the 1957 counts, the ratio of fawns to
adult females was obtained from a sample of 910 animals and the
ratio of yearlings to adult females from a sample of 218
reindeer. In these samples there were 75 fawns and 45 yearlings
per 100 adult females. In the 1963 counts the ratios were 60
fawns and 26 yearlings per 100 females in samples of 1,652 and
705, respectively. It would be expected that deterioration of the
range, with associated reduced physical welfare of the reindeer,
would lead to poor fawn survival through their first winter,
resulting in low yearling to adult ratios. Calculation of the
actual annual rate of increase from these ratios is dependent
upon knowledge of the adult sex ratio which was not available in
either 1957 or 1963. It was often not possible to distinguish sex
and age in the total counts; therefore our composition counts
were based on samples of the total population. Because bulls were
segregated from females and young when we were on the island, the
composition counts did not reflect the true proportion of bulls
in the population. However, if one assumes a ratio of 57 bulls:
100 cows in the adult segment of the population (the sex ratio of
animals over 11/2 years of age among the skeletal material from
the die-off ), the net annual increment to the population, after
the winter but before the spring fawning period, would have been
in the neighborhood of 29 percent in 1957 and 17 percent in 1963.
In 1963 the excessive population on the range was not only
reflected in reduced fawn survival, but physical characteristics
of the reindeer had changed as well, and the range vegetation had
been significantly altered. There was ample evidence of
overpopulation and the stage was apparently set for the wholesale
die-off that followed. Although no one was present on the island,
there is strong presumptive evidence that the dieoff occurred
during the winter of 196364 and apparently largely in the
On May 18, 1964, a flight was made over the island in a P2V
Navy ice reconnaissance plane in the hope of obtaining a
population count of the reindeer through the use of aerial
photography. The island was snow-covered with small patches of
bare ground visible on wind-swept ridges and south exposures. No
reindeer were seen and, even though large groups of reindeer
should have been visible under these conditions, we believed that
we failed to see them because of the relatively high speed of the
plane and reluctance of the pilot to fly at a low altitude over
the mountainous terrain. We were not aware, of course, that a
die-off had already taken place.
The first realization of the die-off came when Coast Guard
personnel went ashore on St. Matthew Island on August 14-16,
1965, to hunt reindeer for recreation. The men hunted in several
parties and made a fairly systematic search of the island during
three days of unusually favorable weather. On the third day, one
group of reindeer, estimated at about 40, was observed near the
southeastern end of the island. No other reindeer were seen and
the men felt that these were probably the only reindeer remaining
on the island. These men also reported that many reindeer
skeletons were scattered about, bleached white with no flesh or
hide remaining (personal communication ). It seems unlikely that,
if the die-off had occurred during the winter of 1964 65 rather
than 1963-64 the skeletons would have been bleached and free of
meat and hide to the extent that this report indicated. When we
were on the island during 1966, moss had already begun to grow on
many of the bones where they were in contact with moist soil, and
the skeleton sites, when soil moisture conditions were favorable,
were also characterized by lush growth of certain grasses and
fortes which have high nitrogen requirements (Fig. 3). These
plants are normally restricted to areas adjacent to the bird
cliffs which are fertilized by bird droppings, and to disturbed
soil near fox burrows and vole colonies. The growth forms of
these plants indicated that they had been present for more than
one season of growth.
Forty-two live reindeer were on the island when we arrived in
1966. These were counted from the ground in a thorough search of
the island and this count (minus 10 animals which were shot) was
confirmed from the air on the day we left the island. No fawns or
yearlings were present among them and the sample of 10 reindeer
also indicates that there had been either no reproduction or no
fawn survival since the die-off. Fawns born in the spring of 1964
would have been just over 2 years of age in 1966, and the
youngest animal in the sample was just over 4 years of age. The
absence of reindeer in the 3-year-old category was also
consistent with an assumed 1963-64 die-off since animals in their
first winter at the time of the die-off would have been more
subject to mortality than prime-age animals.
The winter of 1963-64 on the islands of the Bering Sea was one
of the most severe on record from the standpoint of amount and
duration of snow on the ground and extreme cold. Weather data
were available from the two locations, Mekoryuk on Nunivak Island
and St. Paul in the Pribilof Islands, about 250 miles to the east
and southeast respectively (U. S. Weather Bureau 1964, 1965).
Winter weather conditions on St. Matthew Island are generally
milder than on Nunivak which is under a stronger continental
influence, and St. Matthew Island has more snow and cold than the
Pribilofs which lie almost four degrees of latitude farther
south. On Nunivak Island the greatest snow accumulation on the
ground during the following months was: January, 31 inches;
February, 42 inches; March, 47 inches; and April, 48 inches. This
amount of snow for each of these months in 1964 was the greatest
during the 20-year record. The average temperature for February
was also the coldest on record for that month. At St. Paul Island
snow accumulation during the following months was: February, 33
inches; March, 32 inches; and April, 27 inches, also records for
this station. Temperatures during February at St. Paul were 7.8
degrees below the monthly mean and were the second coldest in the
20-year record for that month.
With this weather pattern, it is likely that the availability
of forage was greatly restricted in late January and February,
and the most acute situation was reached sometime after the turn
of the year and probably in February or March. That starvation
was the cause of death of the reindeer during this period was
verified by examination of the medullae of the long bones among
the skeletal material. Without exception the cavities were
hollow, indicating that no fat was present in the marrow at the
time of death. The fat, when present, is resistant to
decomposition and will be present in the bones 5 or more years
after the death of the animal. This criterion for evaluating
physical condition at the time of death has been used
successfully among other cervids (Cheatum 1949).
Bones of fetuses were found among the remains of several
female reindeer that succumbed during the die-off and they
provided a basis for measuring the size of the fetuses at the
time of death. Estimated body length of four fetal remains varied
from 380 to 480 mm. Davey (1963) obtained body length
measurements from 11 fetuses recovered from reindeer shot on St.
Paul Island during January and February, 1963, and these varied
in size from 8 to 9 inches ( 203-229 mm ) on January 19 to 12 to
15 inches (305 381 mm) on February 15. Since the St. Matthew
Island fetuses were only slightly larger than the St. Paul
specimens of February 15, it appears that the four adult females
carrying the fetuses died in late February and March.
The fact that the reindeer skeletons tended to be grouped (
Fig. 3) suggests that the animals died over a very short period
of time; perhaps they were members of a larger band and died
during the course of a bedding period. Frequently 10 or more
skeletons were found in such close proximity.
The skeletons or other remains of 31 reindeer were found in
1957 and 25 in 1963 and, when possible, they were sexed and aged.
No significant differences in the sex and age characteristics
were found between the two samples. In both years, animals over 5
years old predominated and males outnumbered females two to one,
although some sampling bias undoubtedly existed because the large
bleached antlers of bulls are more visible from a distance than
are those of cows.
In 1966, skeletal remains of 241 reindeer that had succumbed
during the die-off were examined for sex, age, and other
characteristics. Only those skeletons from which sex and age
could be recorded were included. In the case of animals less than
1 year of age, sex could not be accurately determined. In the
overall sample there was a tendency for the small bones of fawns
to become scattered and broken and thus less apparent among the
tundra vegetation than the skeletons of older reindeer and this
probably contributed to a sample bias.
The possibility of a bias among adult animals because of the
different methods of sex determination was considered. However,
the sex ratio of the subsample identified on the basis of the
pelvis was the same as that identified by antlers. Among the
sample of 193 animals over 1 year of age which were identified by
sex, 41 percent were males and 59 percent females, which is a
significant alteration from the assumed equal sex ratio at birth
(X2 test; P < 0.02). However, when examined by individual
age-classes (Table 1) it is apparent that the sex ratio,
essentially equal in the 1 ˝-year class, shifts in favor of
females among the 6 1/2 and older animals. This disproportionate
adult sex ratio is consistent with the heavier mortality of males
indicated by the 1957 and 1963 natural mortality data, and is
also consistent with findings among other cervid populations (
Gunvalson et al. 1952 and Klein 1965).
The physical condition of the reindeer during 1957, 1963, and
1966 showed a pronounced difference. The 1963 animals, in
comparable sex and age-classes, were considerably smaller in both
body mass and skeletal proportions than the 1957 reindeer. The
differences are illustrated in Tables 2 and 3. In Table 3, slopes
and elevations of regressions of body characters against age are
compared between 1957 and 1963 for the St. Matthew Island
reindeer. The significant differences in elevation of regression
lines between the two periods indicate that body size differences
between the two years are consistent for all age-classes. The
differences in slopes, on the other hand, reflect actual
differences in growth rates of the reindeer in 1957 and 1963.
In 1957 the St. Matthew Island reindeer were in excellent
condition, exceeding weight ranges of reindeer in domestic herds,
including average weights from the Nunivak Island herd which was
the source of the original animals introduced to St. Matthew
Island (Table 4). The large size of the reindeer in 1957 was
undoubtedly the result of their recent establishment on a very
favorable range (Fig. 4) and the decrease in body weight and
skeletal size in 1963 was undoubtedly the product of poorer
nutrition, as a result of increased population pressure. However,
it is noteworthy that adult weights in 1963, although greatly
reduced from 1957, were nonetheless comparable with those from
domestic herds, suggesting that in most cases domestic reindeer
exist under conditions considerably less than optimal.
Christian (1963) and other workers in the area of
physiological mammalogy relate decreasing body size in situations
of population increase with density-dependent physiological
stress. While there is evidence to support growth depression
resulting from stressful situations in laboratory populations of
rats and mice (Crew and Mirskaia 1931, Calhoun 1950, Strecker and
Emlen 1953), growth of wild ungulates appears to be more directly
related to the qualitative and quantitative aspects of the food
supply which may not necessarily be related to the density of the
population ( Riney 1955, Cowan and Wood 1955, Klein 1964).
The reindeer shot in 1966, all 4 years old or older, represent
animals that were alive in 1963 before the die-off. All but one
were at least 3 years old in 1963 and therefore had attained
essentially all of their growth before the die-off. One would
therefore not expect to see any growth response in these animals
to the reduced competition for high quality range vegetation, and
the body measurements confirm this. The weight of the females in
1966, however, substantially exceeds the average weight for the
1963 adult females. Probably this resulted from reduced
competition for high quality forage after the winter of 1963-64
and because the 1966 females had not produced young since the
die-off. The absence of the burden of gestation and lactation
undoubtedly resulted in a substantial conservation of energy.
The reproductive status of females has been used as an index
to physiological welfare ( Cheatum and Severinghaus 1950, Myers
and Poole 1962). The reproductive history of female reindeer
collected in 1963 and 1966, as determined from ovarian
examination, is given in Table S. Unfortunately, ovaries from the
1957 collections were lost in storage. In drawing conclusions
from the ovaries, it should be borne in mind that identifying the
various ovarian bodies was difficult, owing to variation in their
stage of development or retrogression and the lack of suitable
reference material; consequently, misinterpretation may have
resulted. Also, reconstructing the reproductive history of an
animal depends upon accurate aging, and while aging the animals
by tooth eruption and wear yielded results consistent with other
findings, the method was not based on known-age animals.
Among the females collected in 1963 over 1 year of age, two
had corpora albicantia corresponding in number to their age. This
may indicate that they conceived as fawns and gave birth to their
first young at 1 year of age, although an error may have been
made in estimating their age, or one or more of the "corpora
albicantia" may have been accessory corpora albicantia of
pregnancy similar to those observed among elk ( Halazon and
Buechner 1956). Two other females over 1 year of age and the
1-year-old female had apparently not conceived in their first
year. The one nonlactating 1963 adult female showed no indication
of previous pregnancies although follicular development appeared
normal and brown spots, interpreted as scars of erupted
follicles, were present throughout the ovaries. There was no
apparent explanation for the reproductive failure of this animal
as it was in good condition with abundant fat reserves. The fact
that two of the 1963 females appeared to have conceived as fawns
is surprising. Although breeding of fawns quite likely
contributed to the high rate of increase during the early years
after the introduction on St. Matthew Island, it seems doubtful
that it could have been common during the period of high density
when rates of increase were much lower.
The 1966 females apparently produced young before the die-off,
with two exceptions: the 4-year-old animal which was a yearling
in 1963, and one whose reproductive history is questionable.
However, there was no indication that conception took place in
any of these animals after the die off. The appearance and number
of ovarian brown spots, which were interpreted as scars from
erupted follicles, suggest that several ovulations took place
without conception occurring during the years following the
die-off. It does not appear likely that their failure to breed
resulted from nutritional factors. Also physiological stress
caused by excess population density, which has been implicated in
reproductive failure in rodents and inferred in other mammals
(Christian and Davis 1964), should not carry over after the
Perhaps the most plausible explanation of the lack of
reproduction lies among the males rather than the females. In the
1966 sample only one male was collected. No other males were
observed among the remaining 32 reindeer although admittedly one
or more may have been overlooked owing to small antler size.
Normally at this time males would have substantially larger
antlers than females, but the antlers of the one male collected
were smaller than the average size of the female antlers. It can
be speculated, however, that because reproductively active males
are more susceptible to winter mortality than females, none of
them survived the extreme conditions that brought about the
nearly complete annihilation of the herd. If this is true, the
absence of pregnancies after the die-off may have been due to the
lack of reproductively capable males. The one male known to
survive may not have been reproductively active after the
die-off. Its relatively low weight and smaller antler growth
under conditions which brought about opposite effects in the
surviving females tend to support this assumption.
Twelve reindeer specimens in 1957, 15 in 1963, and 10 in 1966
were examined for parasitism. While sample sizes are too small to
enable statistical comparisons, lung worms (Dictyocaulus sp.)
were found in three of the 1963 animals and in none of the 1957
or 1966 reindeer. None of these infestations were acute. Skin
warbles, which commonly infest reindeer and caribou on the
mainland, apparently did not establish in the St. Matthew Island
herd, for none of these parasites nor the characteristic scars
they leave on the skin of the host were found in any of the
Lung worm, which has been implicated in mass mortality among
other cervids ( Cowan 1951), may have contributed to reduction of
the St. Matthew herd, but it certainly was not present in
epizootic proportions during the summer preceding the die off
Although parasitism may be the actual agent of death in many
instances among wild ungulate populations, it is usually
associated with debilitation of the animals from other causes
such as malnutrition.
The vegetation on St. Matthew Island is of the arctic tundra
type and is of a more xeric nature than that of the Pribilof
Islands to the southeast. All plants are low growing and the
annual growth of only a few fortes and grasses exceed 30 cm in
height. Willows ( Salix spp. ), the only shrubs commonly present,
are decumbent in form.
Winter reindeer range on St. Matthew Island is necessarily
restricted to windswept areas which are blown free, or nearly
free, of snow. Drifted snow collects in stream valleys,
depressions, and on the lee side of hills, and greatly restricts
availability of vegetation. By nature of their exposure and lack
of significant snow cover, the windswept areas support xeric
plant communities adapted to the harsh microclimate. A
lichen-willow-sedge complex predominated on the winter range
Until 1957, the greatest concentration of winter use by
reindeer was on the two large dry flats and adjacent low ridges
on the southeastern end of the island. Late winter aerial
observations made by Rhode in 1955 revealed large numbers of
reindeer in these areas ( personal communication ).
Vegetation on the heavily utilized wintering areas adjacent to
Big Lake and Cape Upright showed the pronounced effect of heavy
reindeer use as early as 1957. Lichen growth had been seriously
depleted through the combination of winter grazing, trampling,
and shattering, and actual removal of the dry, shattered pieces
of lichen by the persistently strong winds. With wind velocities
often averaging more than 20 miles an hour during winter months,
the potential for plant desiccation and erosion is great. By
1963, lichen growth, which formerly occupied slight depressions
between raised hummocks of prostrate willows, had been almost
completely eliminated (Fig. 5). In the past, lichen growth
apparently was quite similar to ungrazed areas on reindeer-free
Hall Island where the lichen mat was 8-12 cm deep (Fig. 6). In
1963 the lichen mat on the old winter range areas seldom exceeded
1 cm in depth and was composed of badly shattered lichens usually
unattached to the ground. These same areas showed little change
when examined in 1966. The fractured parts of lichens remaining
on the ground surface consisted in large part of the nonliving
basal parts from which regrowth is not possible. However, there
may have been enough living material present to allow for renewal
of the lichen mat, but any regrowth will be exceedingly slow. The
preferred lichen species, such as Cladonia rangiferina, are the
most vulnerable to shattering through trampling, while the more
resilient forms which resist shattering, such as Thamnolia
vermicularis, are less palatable to reindeer and apparently made
up a smaller percentage of the original stands.
Willows fared better than lichens under the heavy reindeer use
but by 1963 the willows had begun to show signs of deterioration
as a result of heavy winter browsing. It is apparent from
observations made in 1957 and on adjacent Hall Island that in the
original lichen-willow-sedge stands the willows and sedges were
suppressed by the engulfing growth of lichens. The removal of
lichens by the reindeer stimulated the growth of willows, sedges,
grasses, and some fortes but by 1963 the reindeer were forced to
rely heavily on the willows. Comparison of vegetation in fenced
and unfenced plots showed an apparent increase in density of
willows in the plots that were protected while in the unprotected
plots they decreased, but these differences are not statistically
Sedges and grasses continued to increase in density under the
continued and increasing grazing pressure. Statistically
significant increases in both sedges and grasses were apparent in
the fenced and unfenced vegetation plots in 1963 (Tables 6 and
7). Evidence from other reindeer ranges indicates that when
lichens are depleted, grasses and sedges are grazed extensively
during the winter (Palmer 1929). At the time of the die-off,
crowberry (Empetrum nigrum) was apparently the only vegetation
available in any volume as evidenced by ruminal material still
present among the skeletons.
Summer forage use by reindeer did not result in significant
alteration of the vegetation complex. During the 1957 summer
field studies, reindeer were observed to make almost exclusive
use of the well drained sedge meadows and bog meadows where
sedges were very common and were the predominant plants eaten by
the reindeer. On the drier, better-drained meadows, Carex
nesophila was the most abundant sedge and received the brunt of
summer use. The wetter, boggy sites support a wider variety of
sedges, but C. aquatilis is usually the dominant form and in
these sites it received the heaviest use during 1957. Other
sedges, grasses, leaves stripped from willows, and fortes were
also important components of the summer diet of the reindeer. All
vegetation types received some summer use by reindeer; however,
the types with a high proportion of sedges and grasses appeared
to support the brunt of summer grazing.
During the 1963 studies, heavy reindeer pressure on the summer
forage was evident but no significant lasting damage was noted.
Closely cropped sedges and grasses were present in all vegetation
types supporting these plants but were most extensive in moist
but well-drained meadows, on lake shores and lake floodplains,
and on the drier slopes of hills. There appeared to be sufficient
summer forage on the island, but competition for the most
nutritious and palatable plants was undoubtedly keen. Evidence
from other reindeer ranges in Alaska indicates that summer range
seldom suffers from overutilization, while winter range condition
varies with population pressure and appears to be the most
important factor in population control. However, the importance
of summer range in the ecology of the reindeer may be greater on
an island where opportunity for movement is restricted.
Summer grazing is apparently seldom permanently destructive to
moist subarctic tundra. In fact, indications are that limited
grazing of the annual growth of sedges, grasses, and some fortes
is actually beneficial in stimulating forage production. Harmful
effects on summer range are limited to trampling vegetation and
compacting loose, moist soil where movements of large numbers of
animals are constricted by narrow valleys and other terrain
features. Throughout the spring and summer, when actively
growing, plants are able to withstand considerable trampling and
still recover rapidly. In addition, the high humidity which
accompanies the persistent spring and summer fogs on St. Matthew
Island keeps the lichens moist and resilient and less subject to
shattering than in a drier atmosphere.
The nutritive quality of the low-growing plants which make up
the summer forage for reindeer on St. Matthew Island can
apparently be very high. This is indicated by the excellent
physical status of the reindeer in 1957. On St. Matthew Island
the variations in exposure resulting from irregularities in
terrain account for a wide range in plant development and
maturity. Also, the cool moist summers delay maturity and curing
of vegetation. Consequently, during its most nutritious period,
the early stages of growth, vegetation is being produced over an
extended period. Under the heavy stocking of the range in 1963,
competition was apparently great enough to restrict the
consumption of highest quality forage by individual reindeer to a
minimal portion of their diet.
Selected forage samples collected in 1963 were analyzed
chemically for nutritive value and were found to be of relatively
high quality. Rumen samples from reindeer shot during 1963 and
1966 were washed to remove the microorganisms and ruminal fluid
components and then analyzed chemically as a basis for judging
the quality of the forage consumed ( Klein 1962 ). Table 8 shows
that for 1963, nutritive values of the washed forage from rumen
contents were much lower than the selected forage samples, and
apparently reflect the limitation upon the reindeer to select
forage qualitatively which was imposed by the high population
density. In the 1966 rumen samples, percent protein had increased
and percent fiber decreased in comparison with the 1963 samples,
apparently as a result of the absence of significant competition
among reindeer for the highest quality forage. It is interesting
to note in Table 8 that comparative rumen samples from caribou on
Adak Island, where these introduced animals are exhibiting
remarkable growth rates, show protein and fiber levels even more
favorable than those in the 1966 St. Matthew Island samples. In
Table 9, comparisons are made between protein and fiber levels of
gross rumen samples from St. Matthew Island reindeer and reindeer
in a domestic herd on the Seward Peninsula, near Nome.
Significantly higher protein levels and lower fiber levels among
the St. Matthew Island material, both before and after the
die-off, than among rumen samples from the managed reindeer herd
emphasize that present domestic reindeer herding practices are
seldom based on a knowledge of range ecology.
Range Carrying Capacity
With regard to ungulate range, it can perhaps be stated that
forage quantity acts primarily to govern population size while
quality determines the size of the individual. Further, in
northern regions, food limitation is most critical during the
winter period while qualitative variations in the food supply
make themselves felt during summer when the physiological demands
of animals are highest and growth is most rapid (Klein 1964).
Thus range carrying capacity involves two quite different
criteria: the winter component which governs the upper limit of
the population, and the summer component which determines the
physical stature of the individual. Of course, seasonal
components of the annual physiological cycle of growth and
maintenance in ungulates are not completely independent of one
another. Physiological welfare in summer affects reproductive
success and winter survival and, hence, rate of population
increase; physiological status at the end of winter can influence
growth and survival of young and rate and time of initiation of
summer fat accumulation in adults.
Various authors have made estimates of grazing capacity for
reindeer. Palmer (1929) listed 16-18 reindeer per square mile as
the maximum for safe range use and he later (1934) suggested that
this might be too high a density for most ranges. Hustich (1951)
gave a figure of 13 reindeer to the square mile for the lichen
woodland of Labrador. These estimates presumably are for winter
range. The density of reindeer on St. Matthew Island in 1957 was
10.5 per square mile and by 1963 it had increased to 46.9 per
square mile. It is noteworthy that on St. Paul Island, reindeer
reached a density of 49 per square mile just before the
"crash die-off' there in the 1940's ( Scheffer 1951).
Estimates of desirable stocking on the summer range are
generally lacking in the Russian, Scandinavian, and North
American literature. Palmer ( 1934: 23-24 ) listed 6 acres (107
reindeer per square mile ) as the combined spring and summer
range requirement of reindeer on the basis of studies of fenced
reindeer but suggested lower stocking levels on open range. This
is not directly comparable to the St. Matthew Island densities
because utilizable range is much less than the total land area on
the island. Probably as much as half of the island is covered by
rock scree which is completely unvegetated except for widely
scattered crustose lichens. In addition much of the area utilized
as winter range was not used by reindeer in summer.
Mechanisms of Population Control
The reindeer population on St. Matthew Island increased
rapidly to a peak which was followed by a crash. This pattern has
been observed among other animal populations under varying
conditions, but most often among introduced species on islands.
Population "explosions" and ensuing die-offs on islands
have been reported for reindeer on the Pribilof Islands (Scheffer
1951), cottontail rabbits (Sylvilagus floridanus) on Fishers
Island, New York (Smith and Cheatum 1944), and moose ( Alces
alces ) on Isle Royale in Lake Superior following their arrival
there (Mech 1966). Explanations for this type of response of
introduced animals may lie in the characteristics of the new
environment or in the lack of plasticity of the introduced
species. It is conceivable that an environment containing several
diverse potential population-regulating mechanisms (for example,
food supply, predators, interspecific competition ) would bring
about a more gradual control of an introduced species than an
environment with only one limiting mechanism such as food supply.
Therefore, one would expect that the more complex the environment
in terms of the flora and fauna present, the more graded would be
the response of the introduced species. This explanation has been
used, of course, to account for the prevalence of cyclic species
in northern regions where ecosystems are characteristically less
complex than in temperate or tropical regions. Island ecosystems
also tend to be less complex than continental ones. Environmental
limitations on islands, especially small ones, are finite. There
is no continuum from favorable to less favorable habitat for a
species occupying an entire island. Island ecosystems, although
sparse from a species standpoint owing to restricted access, tend
to be younger than continental ecosystems, with the result that
there has been less time for the development of complex
Certain species appear less inclined to wide population
fluctuations than others when introduced to new environments. The
wolves of Isle Royale are a classic example of a new and
successful species stabilizing at a level commensurate with the
food supply (Mech 1966). There are innumerable instances of the
Norway rat, the house mouse, and other species associated with
man, gaining access to islands in temperate and tropical regions
and, once established, maintaining relatively stable populations.
Reindeer have also been introduced to islands without
experiencing the wide fluctuations that occurred on St. Matthew
Island and the Pribilofs. On Atka and Umnak Islands in the
Aleutians, introduced reindeer appear not to have undergone large
scale die-offs although accurate records of their population
levels are not available. In the Southern Hemisphere the
introduced reindeer of South Georgia have apparently stabilized
at about 4,000 (Bonner 1958). However, winter climatic conditions
are not as severe in the Aleutians or on South Georgia as on St.
Matthew Island or the Pribilofs.
There appears to be a relationship between the self-regulatory
ability of animal populations and the relative stability of the
environments within which they have evolved. For example, the
North American deer that are adapted to early successional stages
of vegetation, which are of a transitory nature, appear not to
have well developed self-regulatory mechanisms and are
characterized by wide population fluctuations. On the other hand
the roe deer (Capreolus capreolus) in Europe (Andersen 1963) and
some bovids, such as the Uganda kob (Adenota kob thomasi)
(Beuchner 1963 ), that are found on relatively stable vegetation
types, appear to have evolved behavioral mechanisms that tend to
contribute to the stability of their populations. The caribou
appear to be intermediate in this respect. The tundra and open
subarctic lichen forests, which are their native habitat, are
climax vegetation types of a very stable nature. Mobility and the
development of the migratory habit appear to be compensating
mechanisms which prevent destruction of the food resource. In
addition, the wolf is an effective predator on caribou and the
two species have evolved a relationship that appears mutually
beneficial at the level of the population.
On St. Matthew Island and the Pribilof Islands ( Scheffer
1951), reindeer were introduced to restricted ranges free of
predators and subjected to insignificant annual harvests. The
normal migratory habit of the species could offer no relief to
the pressure of the animals on the range because of the
restricted sizes of the islands. The populations expanded rapidly
under the good range conditions and winter mortality at first was
light because of the abundant lichen forage. Increasing at
geometric rates, the populations passed from moderate levels,
with respect to the food supply, to excessive populations in only
a few years. On St. Matthew Island, and possibly on the Pribilofs
as well, the rapid increase to the peak population was coincident
with favorable winter climatic conditions.
The large scale die-off of reindeer on St. Matthew Island
during the winter of 1963 64 was apparently the result of a
combination of the following factors: (1) overgrazing of
lichens on the island, which are normally the most important
winter forage, by the large numbers of reindeer; (2) excessive
numbers of reindeer during the winter of the die-off competing
for the very limited available forage; (3) the relatively poor
condition of the reindeer going into the winter as a result of
competition for high quality summer forage during the summer of
1963; and (4) extreme weather conditions, particularly deep snow
accumulation, during the winter of 1963-64, further restricting
the availability of the already depleted winter forage. These
same factors, jointly operative, were apparently responsible for
the reindeer die-off on the Pribilof Islands in the 1940's (
Scheffer 1951). That weather conditions were not the sole factor
in the die-off of reindeer on St. Matthew Island is demonstrated
by the good survival of the reintroduced reindeer on St. Paul
Island during the same period (F. Wilke in correspondence 1966).
Also, on Nunivak Island, although considerable mortality occurred
among the reindeer there during the winter of 1983 64, no large
die off resulted.
Food supply then, through interaction with climatic factors,
was the dominant population-regulating mechanism for reindeer on
St. Matthew Island. Other factors of population control, such as
disease or parasites and predation, can be ruled out and there is
insufficient evidence to suggest that self-regulatory mechanisms
of a behavioral (Wynne-Edwards 1965), a genetic ( Chitty 1960 ),
or a behavioral-physiological nature (Christian and Davis 1964)
were involved in the dieoff.
ANDERSEN, J. 1963. Populations of hare and roe deer in
Denmark. Proc. 16th Internatl. Congr. Zool. 3:347-351.
BONNER, W. N. 1958. The introduced reindeer of South Georgia.
Falkland Islands Dependencies Survey Sci. Rept. 22. 11pp.
BUECHNER, H. K. 1963. Territoriality as a behavioral
adaptation to environment in Uganda kob. Proc. 16th Internatl.
Congr. Zool. 3:5963.
CALHOUN, J. B. 1950. The study of wild animals under
controlled conditions. Annals N. W. Acad. Sci. 51: 1113-1112a.
CHEATUM, E. L. 1949. Bone marrow as an index of malnutrition
in deer. New York State Conservationist 3(5):19-22.
, AND C. W. SEVERINCHAUS. 1950. Variations in fertility of
white-tailed deer related to range conditions. Trans. N. Am.
Wildl. Conf. 15:171-190.
CHITTY, D. 1960. Population processes in the vole and their
relevance to general theory. Canadian J. Zool. 38(1):99-113.
CHRISTIAN, J. J. 1963. Endocrine adaptive mechanisms and the
physiologic regulation of population growth. Pp. 189-353. In W.
V. Mayer and R. G. van Gelder (Editors), Physiological mammalogy.
Vol. I. Academic Press New York. 381pp.
, AND D. E. DAVIS. 1964. Endocrines, behavior, and population.
Science 146(3651): 1550-156.
COWAN, I. McT. 1951. The diseases and parasites of big game
mammals of western Canada. Proc. Annul British Columbia Game
Convention 5: 37-64.
, AND A. J. WOOD. 1955. The growth rate of the blacktailed
deer ( Odocoileus hemionus columbianus ). J. Wildl. Mgmt. 19(3)
CREW, F. A. E., AND L. MIRSKAIA 1931. The effects of density
on an adult mouse population. Biol. Generalis 7:239-250.
DAVEY, S. P. 1963. Reindeer and their management on St. Paul
Island, Alaska. Unpub. report, U. S. Burl Commercial Fisheries.
Seattle, Washington. 34pp.
ELLIOT H. W. 1882. Report on the seal islands of Alaska. U. S.
Commercial Fish and Fisheries Spec. Bull. 176. 176pp.
GUNVALSON, V. E., A. B. ERICKSON, AND D. W. BURCALOW. 1952.
Hunting season statistics as an index to range conditions and
deer population fluctuations in Minnesota. J. Wildl. Mgmt. 16(2)
HALAZON, G. C., AND H. K. BUECHNER. 1956. Postconception
ovulation in elk. Trans. N. Am. Wildl. Conf. 21:545-554.
HUSTICH, I. 1951. The lichen woodlands in Labrador and their
importance as winter pastures for domesticated reindeer. Acta
Geog. 12(1): 1-48.
KLEIN, D. R. 1959. Saint Matthew Island reindeer-range study.
U. S. Fish and Wildl. Serv. Spec. Sci. Rept.: Wildl. 43. 48pp.
. 1962. Rumen contents analysis as an index to range quality.
Trans. N. Am. Wildl. and Nat. Resources Conf. 27:150-164.
. 1964. Rangerelated differences in growth of deer reflected
in skeletal ratios. J. Mammal. 45(2):226-235.
1965. Ecology of deer range in Alaska. Ecol. Monogr.
KRAMER, C. Y. 1956. Extension of multiple range tests to group
means with unequal numbers of replications. Biometrics 12 (3):
KREBS, C. J., AND I. McT. COWAN. 1962. Growth studies of
reindeer fawns. Canadian J. Zool. 40(5) :863-869.
MECH, L. D. 1966. The wolves of Isle Royale. Fauna of the
Natl. Parks of the U. S., Fauna Series 7. 210pp.
MYERS, K., AND W. E. POOLE. 1962. A study of the biology of
the wild rabbit, Oryctolagus cuniculus ( L. ) in confined
populations. III. Reproduction. Australian J. Zool. 10(2)
PALMER, L. J. 1929. Improved reindeer handling. U. S. Dept.
Agr. Circ. 89. 18pp.
1934. Raising reindeer in Alaska. U. S. Dept. Agr. Misc. Publ.
RINEY, T. 1955. Evaluating condition of freeranging red deer
(Cercus elaphus), with special reference to New Zealand. New
Zealand J. Sci. and Technol. 36(5):429 463.
SCHEFFER, V. B. 1951. The rise and fall of a reindeer herd.
Sci. Monthly 73 (6): 356-362.
SKUNCKE, F. 1968. Reindeer ecology and management in Sweden.
(In press.) Biol. Papers Univ. Alaska.
SMITH, R. H., AND E. L. CHEATUM. 1944. Role of ticks in
decline of an insular cottontail population. J. Wildl. Mgmt.
SNEDECOR, G. W. 1956. Statistical methods. 5th ed. Iowa State
University Press, Ames. 534pp.
STEEL, R. G. D., AND J. H. TORRIE. 1960. Principles and
procedures of statistics. McGraw-Hill Book Co., Inc., New York.
STRECKER, R. L., AND J. T. EMLEN, JR. 1953. Regulatory
mechanisms in house-mouse populations: the effect of limited food
supply on a confined population. Ecology 34(2):375-385.
U. S. WEATHER BUREAU. 1964. Climatological data Alaska. Vol.
49 (1-13): 1-228.
1965. Climatological data Alaska. Vol. 50(1-13): 1-244.
WYNNE-EDWARDS, V. C. 1965. Self-regulating systems in
populations of animals. Science 147(3665): 1543-1548.