Biology_of_Mustelids_Vol_1.pdf

114.
Furthe~on 19.7.36, a male ermine was trapped which showed enlargement of
the testicles (dimensions 7 by 16 mm):
and between 10 and 20 November 1936,
double or paired tracks were observed of "courtin~' male and female ermine,
over a distance of 1.5 km
(trampling down in some places, crawling on the
belly, and other signs of mating behaviour similar to those observed in
March) •
In summary,
these data on the periods of mating and birth, suggest
that the breeding season of the ermine is very prolonged, and may possibly
include some latent period, and that a false rut or mating occurs in March
and April.
N.D. Grigortev (1938) likewise concluded that there is a
prolonged gestation, and that mating actually occurs during the autumn.
If, however, mating does occur in spring, then the gestation period of
female ermine must be only about one and one half months.
Observations of nests with young were made during the nesting
period.
The sites chosen by the ermine were often alike in different
habitats (see Table 2).
Marshy ground is no obstacle to nesting for
ermine:
earlier, M.M. Baryshev (1931-33) had twice found broods of ermine
in covered nests among purple willow shrub in flood plains.
If the nest
is formed in a burrow, it is made as a circular chamber, having a diameter
of about 30 cm.
Apart from the principal burrow, the ermine also have a
number of temporary refuges nearby.
Dry leaves usually form the floor of
the burrow, or wool or skin from prey animals.
Sometimes reed-mace seeds,
tow, or wool from domestic animals is used.
The young are born naked and blind and are about 5 to 5.5 cm long.
Their eyes open in about 10 days, (a) and at the same time, their fur begins
to grow.
By the middle of August,
the young males have reached the size of
an average female,
and by November they are almost full-grown.
The young
ermine leave the nest at the age of about two months,
but the family sta~ in
(a) Intensive observations on young born in captivity (M~ller 1970 : 343)
show that the eyes open at 34 days at the earliest, range 34-42 days. - Ed.