During the 1997–2006 and 2010–2011winter seasons, in the area of Morozova Gora (the nature reserve "Galichya Gora"), in Russia, 1200 samples of various substrata were taken, most of which were 4500 cm3 in volume. In total, 41,854 specimens of 690 species belonging to 52 Coleoptera families were registered at overwintering sites.
The analysis of the peculiarities of imago Coleoptera groups in the major winter habitats showed that in most of the investigated substrata representatives of the Staphylinidae family prevailed both in terms of species diversity and number. It is only under the bark of trees and in deadwood that Carabidae are the most numerous, whereas Latridiidae are prevalent in tinder fungi. Turf has the maximal species saturation during the winter season (the highest percentage of species referring to 18 families was registered here), as well as plant litter (10 families), with turf being the preference of 8 families richest in species diversity.
The imagos of a number of families relatively rich in species – Cantharidae, Malachiidae, Melandryidae, Mordellidae, Oedemeridae, Meloidae, Scraptiidae and Anthribidae – were not found at overwintering sites, which is explained by the preimaginal overwintering of most representatives of the abovementioned families.
It was shown that in substrata which are the least suitable for the overwintering of the imago of most Coleoptera species, the highest percentage of the predominant species was registered since more accessible substrata are used as overwintering sites by the same species from different habitats, which decreases the concentration of imago beetles of certain species there.
A study of the peculiarities of species distribution (with no less than 30 specimens) among overwintering sites showed that the largest number of stenotopic species was registered in droppings (9 species). Then follow the substrata (in decreasing order): turf (5), hay (grass sward, haymow, meadow) (4), decomposing hay (3), decomposing wheat (3) and flour (3), plant litter (2), rotten birch stumps (1), decaying plant matter (1). Stenotopic Coleoptera species were not found in the following substrata: sandbar, decayed plant matter, soil mixed with decomposed hay and droppings, clumps of twigs and stems, hay (a field of perennial grasses), subcortical space and deadwood, tinder fungi.
Cluster analysis revealed that imago Coleoptera groups overwintering in deadwood-related substrata located above the ground level stand out in their species composition. The imago Coleoptera group overwintering in decomposing wheat and flour is also characterised by a peculiar species composition, cereal pests being one of the factors. The species composition of Coleoptera groups overwintering in turf and plant litter as well as in substrata with decaying plant matter (decomposing hay, droppings, plant remains etc.) displayed the highest levels of similarity.
The use of a uniform procedure for collecting material allowed calculating the average number of Coleoptera species overwintering in various substrata. It resulted in working out the major requirements for overwintering sites preferred by most imago beetles: 1) the substratum should be freeze-protected (among others, due to plant remains decomposition); 2) the moderate moisture of the location is important (extreme dryness and excess moisture of the substratum are both unsuitable for the overwintering of imago beetles); 3) the necessary presence of cavities suitable for overwintering (in hay, rotten wood, under the bark etc.); 4) it is desirable that the substrata contain enough food available in late autumn and early spring (smaller invertebrates, fungi etc.).
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