Weasel — Mustela nivalis Linn. (in Kyrgyz: arys-chichkan)
Kyrgyzstan is inhabited by the mountain Turkestan subspecies, which has a light brown coloration in summer fur (on top) and medium body size compared to other forms inhabiting the territory of the Soviet Union. In Kyrgyzstan, it is found everywhere, from lowlands to high mountains, but is distributed extremely unevenly. Almost everywhere, the weasel is significantly outnumbered by the ermine, and it only predominates over it in certain limited areas. For example, in the Tokmak Reserve in the valley of the Chu River, the highest population density has been recorded — about 3.0 individuals per 10 km². A similar density is observed in the valley of the Turgen-Aksu River (northern slopes of the Kyrgyz Range) — an average of 2.1 individuals per 10 km². It should be noted that these figures refer not to the entire area of the specified regions but only to certain sections. On average, the population density of the weasel in the republic (only according to forest enterprises) is less than 0.25 individuals per 10 km². The foothill areas and mid-mountains of Northern Kyrgyzstan (the basins of the Chu and Talas rivers) are more densely populated, where there are 0.59 individuals per 10 km². Slightly lower (about 0.4) is found in eastern Preissykul, while in its western part, the weasel is practically absent, occurring only as single specimens in certain gorges. In the Osh region, the population density of the weasel is somewhat higher than that of the ermine, but still insignificant on average — 0.19 individuals per 10 km². It is also low in the Inner Tian Shan, only 0.1 individuals per 10 km².
In general, weasels are less common where there are many ermines, and vice versa. On the other hand, both species are apparently hunted by the stone marten in the same way that the sable is hunted in Siberia. Almost everywhere that the population of martens is significant, the number of ermines and weasels drops to a minimum, sometimes disappearing altogether. This pattern is only detected in counts in individual areas and completely disappears when combining accounting data due to the uneven distribution of species. Often, in neighboring areas, the ratio of the number of martens to small mustelids is opposite, which leads to leveling when summed. For instance, in the Yazgi-Chinsky and Djangi-Dzhol forestry districts, a very high population density for martens has been recorded: 0.08 individuals per 10 km². Even higher density is found in the Kugat and Kyzyl-Ungur forestry districts — 0.13 individuals per 10 km². In these forestry districts, traces of weasels and ermines have not been found. Where martens are scarce, they do not have a significant impact on the populations of the latter two species.
The habitats of the weasel are more diverse than those of the ermine. Unlike the ermine, it prefers open spaces and is more frequently found in steppe and meadow areas, especially those that are bushy and overgrown with tall grass.
The weasel primarily feeds on mouse-like rodents, shrews, and less frequently on other vertebrates. In Northern Kyrgyzstan, young weasels almost reach adult sizes and begin to lead an independent life by the end of June. This may indicate that they are born in April. On July 4, 1964, in the belt of juniper forests of the Talas Range, we observed a young weasel that had not yet reached the size of an adult but was already independent.
The weasel reproduces more slowly than the ermine, with an average litter of 4-7 young.
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