ISSN 10674136, Russian Journal of Ecology, 2012, Vol. 43, No. 1, pp. 62–66. © Pleiades Publishing, Ltd., 2012.
Original Russian Text © M.V. Ushakova, M.V. Kropotkina, N.Yu. Feoktistova, A.V. Surov, 2012, published in Ekologiya, 2012, No. 1, pp. 65–69.
Seasonal differences in environmental conditions
increase with increasing geographic latitude, and
annual rhythms are especially marked in the organ
isms living in temperate and polar zones (Aschoff,
1984; Anufriev, 2008). The autumn–winter period is a
“bottleneck” through which the most adapted indi
viduals pass (Heldmaier and Klinggenspor, 2003).
Most species have developed adaptations allowing
them to survive the adverse period, such as seasonal
migrations, cold resistance, and hibernation. Hiber
nation is considered to be one of the most efficient
mechanisms decreasing the energy consumption. As a
rule, the mortality of hibernating species in winter is
lower than that of the animals remaining active.
In addition to true hibernation, mammals have
another mechanism, where the body temperature
decreases for a short time. It is termed daily torpor.
This behavior is also an important adaptation allowing
the animals save energy, especially during seasonal
acclimation (SchmidtNielsen, 1982;
Life in the Cold
2000). A number of factors are believed to promote the
transition to torpor; these are a shortened photope
riod, a decreased air temperature, a lack of food, etc.
The physiological basis of this response is formed by
endogenous circadian changes in the neuroendocrine
system (SchmidtNielsen, 1982; Rubtsov, 2001).
Recent data have demonstrated that regular torpors
are characteristic of many species of small mammals.
To date, this phenomenon has been described in rep
resentatives of several orders: monotremes, marsupi
als, insectivores, rodents, and primates (
Life in the
, 2000). Torpor in the subfamily Cricetinae was
found and studied under laboratory conditions in
Most of these studies have been
performed by German researchers (
Life in the Cold
Environmental Signal Processing and Adaptation
2003) on animals that were brought to Europe from
Western Siberia (Figala et al., 1973). The pattern of
body temperature variation, the periodicity and dura
tion of torpor, and the mode of decrease in the meta
bolic rate have been determined. The researchers have
concluded that daily torpor allows animals with high
energy consumption at night to save as much as 67% of
daily energy (Heldmaier and Klinggenspor, 2003).
The purpose of our study was to monitor the
changes in the body temperature during the autumn–
winter period and determine the possibility of torpor
and its characteristics in six species of the subfamily
MATERIALS AND METHODS
The study was carried out from September 2008 to
September 2010 at the Chernogolovka Research
Experimental Station of the Severtsov Institute of
Ecology and Evolution of the Russian Academy of
Sciences. Hamsters of the following species were used
Ph. roborovskii, Cricetulus barabensis, Cr. longicau
All experimental animals
) were captured
from natural populations (Table 1). Experiments were
performed on adult males and females over six months
of age. All animals were kept under the same condi
Daily Torpor in Hamsters (Rodentia, Cricetinae)
M. V. Ushakova, M. V. Kropotkina, N. Yu. Feoktistova, and A. V. Surov
Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, Leninsky pr. 33, Moscow, 119071 Russia
Received March 30, 2011
—Study of ecological adaptations, including torpor, related to survival through the adverse conditions
of the autumn–winter season is important for both the estimation of the body reserves in mammals in general
and the search for the ways to increase the coldstress resistance in humans. The changes in the body tempera
ture during the period from October to May were studied in hamsters of six species under the natural photope
riod and temperature conditions. Incidental winter torpor (a drastically decreased physiological activity) was
detected in all species except
; in three of them, it had not been observed before. No specific
combination of conditions causing torpor was identified. Apparently, it is determined by individual characteris
tics of the animal. Torpors were the most frequent in January, at temperatures from –15 to –5
C; their depth
was positively correlated with the ambient temperature. Since torpor is a rare event, it is assumed to be a stored
resource of the body allowing animal to save energy and occurring only in extreme situations.
: torpor, adaptation, body temperature,