Biology_of_Mustelids_Vol_1.pdf

30. \
I,
THE VALIDITY OF BERGMAN'S RULE AS APPLIED TO
INTRASPECIFIC VARIATION IN THE ERMINE
(0 primenimosti pravila Bergmana pri issledovanii vnutrividovogo
raznoobraziya gornostaya)
by
O.V. Petrov
I
I
\
Vestn. Leningr. Univ., Biol. Ser., 9 (2) : 144-14B. 1962.
I~
It is known that the vitality of the ermine is greatly affected
by the temperature of the surrounding environment.
Populations of ermine
living in the far north and south of the region in which they are distri-
buted experience widely differing temperatures.
In the north of Siberia,
in winter, the difference in temperature between the body of the animal
o
and the external environment may reach 80 or more C.
This severe
temperature regime has been important in determining the adaptation of the
ermine to life in an extreme climate (6, 15).
Apart from a direct action on the animal (reduction of the
activity of the adults, increase in mortality rate of the young, etc.),
temperature also has a marked indirect effect.
According to the obser-
vations of V.I. Tikhvinskii (17) and 0.1. Aspisov and V.A. Popov(1), the
decrease in the number of ermine trapped in the Tartar ASSR,
in years with
a cold spring, is not due to the death of ermine from the low temperature,
but to the decreased availability of Muridae for food.
The cold inhibits
the activity of rodents in spring, and it is markedly more difficult for
the ermine, hunting outside their burrows, to obtain enough food when the rodents
are less active.
In addition, in years with a cold spring (according to
the opinion of a number of workers) there is a decline in the rate of
reproduction of the Muridae.
This all leads to a decreased food supply
and to starvation both of the adult and the newborn young stoats.