Biology_of_Mustelids_Vol_1.pdf

142.
Comparison of the results of these investigations on the age
structure of the martens of the Republic, showed that the three age groups
are unequally represented.
Individuals of the first age group comprise
the highest percentage (45.3%);
second place is taken by the second group
(28.6%) while martens of the third age group are in the minority (26.1%).
A somewhat different picture is offered by the structure of
males and females separately. Among the females, young ,martens under a
year form the highest proportion (48.4%), with fewer martens in the
second age group (31.3%) and fewest of all in th~ third age group (20.3%).
The age ratio in males is different:
we observe males over three years
most often (40.9%), with smaller numbers in the first age group (36.4%) and
the smallest in the second (22.7%).
The structure of the total population of martens (by sex and
age groups) was as follows
pride of place is taken by males of the
third age group (25.8%), second place by males of the first age group (22.9%),
third by females of the first age group (17.8%) and then come males of the
second age group (14.4%),
females of the second age group (11.6%) and,
finally females of the third age group (7.5%).
It is important to note that in natural conditions there are
almost half as many males again as females and their numbers in nature(a)
considerably exceed the number of females.
Of the 201 martens studied
by us, 63.7 per cent were males.
Study of the causes of the predominance of individuals of one sex
or age group is of great interest.
V.P. Teplov(5), on the basis of study
of extensive material, made some generalisations on the sex ratio in wild
mammals. We do not have sufficient material at our disposal to show the
causes of the pattern in the population structure of the martens of our
Republic. However, there is no doubt that an important role is played
(a) But see Teplov (1948), Kraft (1966) and Nyholm (1959), in this volume.
- Ed.