Structure of the population of animals by sex and age largely determines its performance. Identify the best (optimal) sex and age ratios for specific areas – the main task of hunting. But in order to be able to manage these relationships, it is necessary to know not only the real-life range of biological constants, but also the factors that determine it, and the value of their variability for the life of animals.
The ratio of male and female moose almost everywhere in the world is 1:1, that is, in the nature of an equal number of individual lives of both sexes. But this is only an average. If you look at all population moose, breaking it by age, we find that at a young age is dominated by males, on average – for every female, there is one male, and in the older age groups is increasing dramatically the number of females.
At the young age of males females are smaller and therefore weaker. Natural to them and kill more. The difference in the sex ratio begins to flatten at age 3.5 – 5.5 years and fizzles to 6.5 – 7.5 years. By this time, the elk have already reached full physical development, and almost as good as the bulls in size and weight. For this reason, the loss of their reduced. In the older age group, in which animals of both sexes, although more different in weight and size, increased mortality of bulls by the victims of fighting in rut and killed by predators and winter strike. After all, the male elk suffer much worse winter, because during rut lose body fat, and find food in deep snow and the growing scarcity of winter pastures is increasingly difficult. That is why the males to the middle and especially the end of winter is so depleted that they become relatively easy targets for predators, they are more die from disease and simply from exhaustion.
Sex ratios are generally unstable. In average conditions of existence of the sex ratio is 1: 1, and is born roughly equal numbers of males and females. With deteriorating living conditions dramatically reduced the number of males, but increases the fertility of males. While improving the living conditions of the same at the beginning ratio gender does not change, but it dramatically increases fertility of females, which then leads to an increase in their total.
In 1942, for example, in Tatarstan, where the number of elk there grew, the ratio of females to males was 60 and 40%, and in 1962, when the winter pastures in the country staliistoschatsya, respectively – 42 and 58%. In the central part of the country at a time when winter pastures were not there exhausted, the number of females everywhere prevailed over the males in the European part of the USSR (10 areas) – 58 and 42%, in the Oka Reserve -67 and 33%.
Thus, the increased population density of moose, causing an unnecessary burden on the winter pastures, causes an increase in the number of males. Exactly the same pattern is observed in many (if not all) other ohotniche-game animals. But what is even more interesting – in cases where males predominate in the population of animals, including their offspring this dominance is expressed to a greater extent.
Therefore, if the number of males was significantly prevails over number of females, so the total number of exploited animals above the natural capacity of land, and it is already pointing to the urgent need to increase the commercial load. If males and females are observed in about equal proportions, the level of annual withdrawals can not be changed. In the same case, where the population is dominated by female animals, then this is evidence of a prosperous state and the continued growth in numbers. Depending on the winter pastures on whether they are depressed or not that far, and on what are the prospects for the growth of livestock, – the rules of commercial loads can be reduced subsequently to increase productivity and the number of animals, as well as land, inhabited by these animals, but can be dramatically improved if the set started degradation winter elk grazing.
Unfortunately, the analysis of age distribution in the population of moose hunting, and most organizations are not prepared, for age harvested moose usually determined "by eye" or not is determined. To this must be added and the unwillingness of hunters to shoot yearlings, as products from them 2 times less than that of the adult elk, although the cost of the license to the same shooting. It turns out that the hunters shoot the animals are not in proportion to those ages that are observed in nature, and the largest – the middle-aged and old. Of course, analyzing a sample, we would have fallen into error. Can not the same population of wild animals consist of middle-aged and old animals! Such a population would obviously be endangered.
In the Pechora taiga, which was host to capture migratory elk in special enclosures, and where they are selective shooting with careful account of sex and age groups, it was possible to form an idea of the relationship between age groups in the population of elk was in a state population growth, stabilization and reduction.
Despite the fact that more than 1,100 have been analyzed hunted elk, the figures given in the table, can not claim absolute accuracy, but it is already possible to follow them, in comparison, for example.
Know what to do when strength moose grows or is on the same level – stabilized. Then you can load commercial and zoom in and out and leave at the same level. But what if the numbers start to decline?
One male can cover several females, but does that mean that in this case you have to shoot mostly males, aims to increase the productivity of the declining population of moose? Do not do that. It would seem that increasing the number of females at the expense of males (meaning ratio percent), it is hoped to obtain a higher increase than the gender balance. The point, however, is not a simple arithmetic.
Usually in the nature of the males of 1.5 and 2.5 years, up about 25% of the sex groups, to drive away from the elk older and stronger bulls. Females are also 1.5 and 2.5 years, freely participate in reproduction. During the breeding season, therefore, for every 100 females have not 100 and 75 males. In addition, there is a significant number (10 – 15%) of male old and weak or unable to participate in the reproduction process. To reduce further the number of males, then subjected to two additional elk population woes: the growth and increasing cases propustovaniya percent weakened offspring by mating of elk with young, poor producers. Sex ratio of 1: 1 is the obviously the optimum level.
And what might be the optimal age structure? Apparently, one in which the predominant age group will be yearlings, but with the condition that the lands can supply growing population all the necessary conditions for normal life of all individuals comprising it, including adequate nutrition during all seasons of the year. In a growing population of juvenile animals must be at least 20% of the total number of individuals in the stabilization of the population – at least 15%, is in a state of depression – less than 15%, more than 10%.
If it is determined that the number of elk in a given area is noticeably shorter, it does not mean you have to stop fishing or weaken its strength, reducing the normal commercial loads. If the depression has been a clear winter pastures, it should further reduce the number of elk grazing on these pastures, ultimately increasing the commercial load, for wiping out the pasture, strength moose inevitably decrease dramatically, even when shooting will be completely stopped.
You should know that periodic worsening living conditions, leading to a temporary reduction in the number of moose – the need, which improve the adaptive reactions of the body against the sharp increase natural and sexual selection.
In other words – have worsened living conditions – killing the weak and the sick, the less fit. There are more males – increased intensity of sexual selection, the females began to cover the most powerful high-grade males, and that will lead to the birth of a viable future.