Dynamics of the Reproduction and Population Structure of Northern Red-Backed Vole Myodes rutilus Pallas, 1779 in the Northern Taiga of Western Siberia

The peculiarities of the reproduction and population structure of northern red-backed vole in the northern taiga of Western Siberia are considered. Rodents were trapped in the snowless period using pitfall traps (guide fences made of polyethylene film) and trap-lines. A total of 2704 individuals of northern red-backed vole have been recorded in the southern strip of northern taiga over a 9-year period and in the northern strip of northern taiga over a 4-year period. The reproductive participation of females was determined by the presence of embryos and placental scars and participation of males by the presence of spermatozoa in the epididymis and size of the testis. The age of voles was determined by M2 root development, as well as by the weight, body length, and thymus development. The reproductive period is up to five months in adult overwintered voles and up to three months in young voles. Overwintered males remain sexually active throughout the snowless period. Overwintered females in the southern strip bring three litters and young females two litters. Most of the overwintered females in the northern strip bring two litters, as well as three litters in rare cases, and young females bring two litters. The northern red-backed vole population is represented exclusively by overwintered animals in the southern strip in April–May and in the northern strip in June. In August and September, young-of-the-year are universally dominant. Males predominate among adults and young animals; the numerical advantage is shifted towards females among overwintered animals only in late summer and autumn.