Coauthor: Irina Rotenko
Among the two marten species which nowadays there are in Belarus i.e. the pine marten and stone marten, mainly pine martens populate the terrain of Naliboki Forest.
The pine marten populates the whole Naliboki Forest and is fairly common predator species in each part of this forested terrain. The population number was more or less stable on a multiannual scale; at least, such a steady situation was recorded in the period since 1983. Coefficient of variation of average population density of the species in winter comprised 20% only. The annual mean of its population density varied from 42 to 93 pine martens per 100 square km of the whole terrain of Naliboki Forest (not only forest habitats), and between-year average of population density was 68 individuals per 100 square km.
Pine martens in Naliboki Forest.
Each year the species distribution was quite uneven with maximal difference in population density about 6 fold. In the localities, where pine stands on sand soils prevail (e.g. Liakhavyja Hory, Lysyja Hory, Siatryshcha), the winter population density of the pine marten was minimal – 20-30 individuals per 100 square km. In contrast, in winter in broadleaved oldgrowth (100-400 years old) in the Biarezina valley the pine marten population density constituted 120-210 individuals per 100 square km. Also, it was found relatively high population density of the predator in extensive mostly old spruce-deciduous forest in north-western part of Naliboki Forest nearby the Vishnieva village at the right side from the A’lshanka small river as well as in the forest fragment between the Brodnaje hamlet, the former Budy hamlet and the Barki Astashynskija locality. In other forest parts the species population density was characterized by intermediate values. Quite often the population density of the pine marten was between 70 and 90 individuals per 100 square km.
Feeding of pine martens in Naliboki Forest was characterized by almost equal use of vertebrate prey (mainly small rodents and also birds) and plant food (mainly fruits), what was revealed in both the warm season (April-October) and cold season (November-March). However, actually pine martens had possibility to feed on fruits in the seasonal period from the end of June till January. Usually, intensive feeding on fruits led to two or even three fold decrease in preying upon small rodents. In summer, when birds nest, consumption of these prey increased 3-10 fold and they comprised about a half of the diet or even more. This trend was especially pronounced in the ecologically rich deciduous broadleaved oldgrowth in the Biarezina valley, where the bird species diversity and biomass were found to be the highest.
Concerning the stone marten, the species is more or less common mustelid species in the villages that are situated at the edges of Naliboki Forest especially at the southern border of the terrain behind the Nioman valley, for instance, in the Liubcha borough. The species appeared there in numbers in the end of 1990s. Within the Naliboki Forest the stone marten was only found common in the large rural opening, on which the Bakshty village and several other villages are placed. This local population usually consists of 10-20 stone martens, e.g. from 5 individuals in 2000 to 24 individuals in 2011. Perhaps, the stone marten expanded into this place in the end of 1990s. At least, I registered stone marten tracks in the Zabiarez’ village in 1998, and at that time locals did not know the species.